Sub-100 fs pulses from an all-polarization maintaining Yb-fiber oscillator with an anomalous dispersion higher-order-mode fiber

DEFF Research Database (Denmark)

Verhoef, A.J.; Zhu, L.; Israelsen, Stine Møller

2015-01-01

, was investigated for different settings of the intracavity dispersion. When the cavity is operated with close to zero net dispersion, highly stable 0.5-nJ pulses externally compressed to sub-100-fs are generated. These are to our knowledge the shortest pulses generated from an all-polarization-maintaining Yb-fiber......We present an Yb-fiber oscillator with an all-polarization-maintaining cavity with a higher-order-mode fiber for dispersion compensation. The polarization maintaining higher order mode fiber introduces not only negative second order dispersion but also negative third order dispersion in the cavity......, in contrast to dispersion compensation schemes used in previous demonstrations of all-polarization maintaining Yb-fiber oscillators. The performance of the saturable absorber mirror modelocked oscillator, that employs a free space scheme for coupling onto the saturable absorber mirror and output coupling...

Wave-packet dynamics in alkaline dimers. Investigation and control through coherent excitation with fs-pulses; Wellenpaketdynamik in Alkali-Dimeren. Untersuchung und Steuerung durch kohaerente Anregung mit fs-Pulsen

Energy Technology Data Exchange (ETDEWEB)

Sauer, F.N.B.

2007-07-01

During my PhD thesis I investigated alkaline dimers with coherent control in a molecular beam as well as with pump-probe spectroscopy in a magneto-optical trap (MOT). The aim of the coherent control experiments were the isotope selective ionization with phase- and amplitude-shaped fs-pulses. Chapter 4 described the gained results of isotope selective ionization of NaK and KRb in a molecular beam by using different pulse formers. For the NaK dimer was the reached optimization factor R{sub Ph} and {sub Ampl}{sup 770}=R{sub max}/R{sub min}=25 between maximization and minimization of the isotopomer ratio ({sup 23}Na{sup 39}K){sup +}/({sup 23}Na{sup 41}K){sup +} with phase and amplitude modulation of the fs-pulse with a central wavelength of {lambda}=770 nm. From the electronic ground-state X(1){sup 1}{sigma}{sup +};{nu}''=0 transfers a one-photon-excitation population in the first excited A(2) {sup 1}{sigma}{sup +} state. The coherent control experiment on KRb was used to maximize and minimize the isotopomer ratio ({sup 124}KRb){sup +}/({sup 126}KRb){sup +}. It was the first coherent control experiment with a spectral resolution of 1.84 cm{sup -1}/Pixel. For the phase and amplitude optimization was the received optimization factor between minimization and maximization of the isotopomer ratio R{sub Ph} and {sub Ampl}=R{sub max}/R{sub min}=7 at a central wavelength of 840 nm. The results showed a stepwise excitation process from the electronic ground-state in the first excited (2){sup 1}{sigma}{sup +} state with a further excitation, that is possible over three resonant energy potential curves into the ionic ground-state. In the second part of my thesis I realized pump-probe spectroscopy of Rb{sub 2} dimers in a dark SPOT. (orig.)

Nonlinear side effects of fs pulses inside corneal tissue during photodisruption

Science.gov (United States)

Heisterkamp, A.; Ripken, T.; Mamom, T.; Drommer, W.; Welling, H.; Ertmer, W.; Lubatschowski, H.

In order to evaluate the potential for refractive surgery, fs laser pulses of 150-fs pulse duration were used to process corneal tissue of dead and living animal eyes. By focusing the laser radiation down to spot sizes of several microns, very precise cuts could be achieved inside the treated cornea, accompanied with minimum collateral damage to the tissue by thermal or mechanical effects. During histo-pathological analysis by light and transmission electron microscopy considerable side effects of fs photodisruption were found. Due to the high intensities at the focal region several nonlinear effects occurred. Self-focusing, photodissociation, UV-light production were observed, leading to streak formation inside the cornea.

Digitally controlled chirped pulse laser for sub-terahertz-range fiber structure interrogation.

Science.gov (United States)

Chen, Zhen; Hefferman, Gerald; Wei, Tao

2017-03-01

This Letter reports a sweep velocity-locked laser pulse generator controlled using a digital phase-locked loop (DPLL) circuit. This design is used for the interrogation of sub-terahertz-range fiber structures for sensing applications that require real-time data collection with millimeter-level spatial resolution. A distributed feedback laser was employed to generate chirped laser pulses via injection current modulation. A DPLL circuit was developed to lock the optical frequency sweep velocity. A high-quality linearly chirped laser pulse with a frequency excursion of 117.69 GHz at an optical communication band was demonstrated. The system was further adopted to interrogate a continuously distributed sub-terahertz-range fiber structure (sub-THz-fs) for sensing applications. A strain test was conducted in which the sub-THz-fs showed a linear response to longitudinal strain change with predicted sensitivity. Additionally, temperature testing was conducted in which a heat source was used to generate a temperature distribution along the fiber structure to demonstrate its distributed sensing capability. A Gaussian temperature profile was measured using the described system and tracked in real time, as the heat source was moved.

High-power parametric amplification of 11.8-fs laser pulses with carrier-envelope phase control

NARCIS (Netherlands)

Zinkstok, R.T.; Witte, S.; Hogervorst, W.; Eikema, K.S.E.

2005-01-01

Phase-stable parametric chirped-pulse amplification of ultrashort pulses from a carrier-envelope phase-stabilized mode-locked Ti:sapphire oscillator (11.0 fs) to 0.25 mJ/pulse at 1 kHz is demonstrated. Compression with a grating compressor and a LCD shaper yields near-Fourier-limited 11.8-fs pulses

Parametric generation of high-energy 14.5-fs light pulses at 1.5 mum.

Science.gov (United States)

Nisoli, M; Stagira, S; De Silvestri, S; Svelto, O; Valiulis, G; Varanavicius, A

1998-04-15

High-energy light pulses that are tunable from 1.1 to 2.6 mum, with a duration as short as 14.5 fs were generated in a type II phase-matching beta-BaB(2)O(4) traveling-wave parametric converter pumped by 18-fs pulses obtained from a Ti:sapphire laser with chirped-pulse amplification, followed by a hollow-fiber compressor.

High-energy-throughput pulse compression by off-axis group-delay compensation in a laser-induced filament

International Nuclear Information System (INIS)

Voronin, A. A.; Alisauskas, S.; Muecke, O. D.; Pugzlys, A.; Baltuska, A.; Zheltikov, A. M.

2011-01-01

Off-axial beam dynamics of ultrashort laser pulses in a filament enable a radical energy-throughput improvement for filamentation-assisted pulse compression. We identify regimes where a weakly diverging wave, produced on the trailing edge of the pulse, catches up with a strongly diverging component, arising in the central part of the pulse, allowing sub-100-fs millijoule infrared laser pulses to be compressed to 20-25-fs pulse widths with energy throughputs in excess of 70%. Theoretical predictions have been verified by experimental results on filamentation-assisted compression of 70-fs, 1.5-μm laser pulses in high-pressure argon.

Direct Observation of Sub-100 fs Mobile Charge Generation in a Polymer-Fullerene Film

DEFF Research Database (Denmark)

Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

2012-01-01

The formation of mobile charges in a roll-to-roll processed poly-3-hexylthiophene-fullerene bulk heterojunction film is observed directly by using transient terahertz spectroscopy with sub-100 fs temporal resolution. The transient terahertz ac conductivity reveals that 20% of the incident pump...

Dynamic characterization and amplification of sub-picosecond pulses in fiber optical parametric chirped pulse amplifiers

DEFF Research Database (Denmark)

Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Rishøj, Lars Søgaard

2013-01-01

We show a first-time demonstration of amplification of 400 fs pulses in a fiber optical parametric amplifier. The 400 fs signal is stretched in time, amplified by 26 dB and compressed back to 500 fs. A significant broadening of the pulses is experimentally shown due to dispersion and limited gain...

Sub-fs electron bunch generation with sub-10-fs bunch arrival-time jitter via bunch slicing in a magnetic chicane

Directory of Open Access Journals (Sweden)

J. Zhu

2016-05-01

Full Text Available The generation of ultrashort electron bunches with ultrasmall bunch arrival-time jitter is of vital importance for laser-plasma wakefield acceleration with external injection. We study the production of 100-MeV electron bunches with bunch durations of subfemtosecond (fs and bunch arrival-time jitters of less than 10 fs, in an S-band photoinjector by using a weak magnetic chicane with a slit collimator. The beam dynamics inside the chicane is simulated by using two codes with different self-force models. The first code separates the self-force into a three-dimensional (3D quasistatic space-charge model and a one-dimensional coherent synchrotron radiation (CSR model, while the other one starts from the first principle with a so-called 3D sub-bunch method. The simulations indicate that the CSR effect dominates the horizontal emittance growth and the 1D CSR model underestimates the final bunch duration and emittance because of the very large transverse-to-longitudinal aspect ratio of the sub-fs bunch. Particularly, the CSR effect is also strongly affected by the vertical bunch size. Due to the coupling between the horizontal and longitudinal phase spaces, the bunch duration at the entrance of the last dipole magnet of the chicane is still significantly longer than that at the exit of the chicane, which considerably mitigates the impact of space charge and CSR effects on the beam quality. Exploiting this effect, a bunch charge of up to 4.8 pC in a sub-fs bunch could be simulated. In addition, we analytically and numerically investigate the impact of different jitter sources on the bunch arrival-time jitter downstream of the chicane, and define the tolerance budgets assuming realistic values of the stability of the linac for different bunch charges and compression schemes.

Two-stage optical parametric chirped-pulse amplifier using sub-nanosecond pump pulse generated by stimulated Brillouin scattering compression

Science.gov (United States)

Ogino, Jumpei; Miyamoto, Sho; Matsuyama, Takahiro; Sueda, Keiichi; Yoshida, Hidetsugu; Tsubakimoto, Koji; Miyanaga, Noriaki

2014-12-01

We demonstrate optical parametric chirped-pulse amplification (OPCPA) based on two-beam pumping, using sub-nanosecond pulses generated by stimulated Brillouin scattering compression. Seed pulse energy, duration, and center wavelength were 5 nJ, 220 ps, and ˜1065 nm, respectively. The 532 nm pulse from a Q-switched Nd:YAG laser was compressed to ˜400 ps in heavy fluorocarbon FC-40 liquid. Stacking of two time-delayed pump pulses reduced the amplifier gain fluctuation. Using a walk-off-compensated two-stage OPCPA at a pump energy of 34 mJ, a total gain of 1.6 × 105 was obtained, yielding an output energy of 0.8 mJ. The amplified chirped pulse was compressed to 97 fs.

Signal-Pressure Curves of Cascaded Four-Wave Mixing in Gas-Filled Capillary by fs Pulses

International Nuclear Information System (INIS)

Chen Baozhen; Huang Zuqia

2005-01-01

The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled capillary by fs pulses are calculated. With a comparison between the theoretical and experimental SPC we have discussed the influence of the walk-off and phase modulation on the SPC. At the same time, we have discussed the possible origin of the first three peaks of the SPC.

Generation of 70-fs pulses at 286 μm from a mid-infrared fiber laser

Science.gov (United States)

Woodward, R. I.; Hudson, D. D.; Fuerbach, A.; Jackson, S. D.

2017-12-01

We propose and demonstrate a simple route to few-optical-cycle pulse generation from a mid-infrared fiber laser through nonlinear compression of pulses from a holmium-doped fiber oscillator using a short length of chalcogenide fiber and a grating pair. Pulses from the oscillator with 265-fs duration at 2.86 {\\mu}m are spectrally broadened through self-phase modulation in step-index As2S3 fiber to 141-nm bandwidth and then re-compressed to 70 fs (7.3 optical cycles). These are the shortest pulses from a mid-infrared fiber system to date, and we note that our system is compact, robust, and uses only commercially available components. The scalability of this approach is also discussed, supported by numerical modeling.

Sub-15 fs multiphoton lithography of three-dimensional structures for live cell applications

International Nuclear Information System (INIS)

Licht, Martin; Uchugonova, Aisada; König, Karsten; Straub, Martin

2012-01-01

Development, morphology and intratissue location of cells are influenced by the 3D nano- and microenvironment. In this paper we demonstrate multiphoton photopolymerization to generate three-dimensional structures for cell culture applications with micro- and nanotopographic features using SU-8 photoresist and mr-NIL 6000 nanoimprint resist. Moving the focal spot of high-repetition rate near-infrared sub-15 fs pulsed laser light by a galvanometric beam scanner in combination with a piezoelectric vertical stage, nearly arbitrary trajectories of polymerized photoresist were generated. This technique can be used to generate cage structures with submicron interior features for live cell applications. Preliminary experiments with PC-3 and HT-1080 cells indicate the influence of the structures on cell behavior. (paper)

Generation of Phase-Stable Sub-Cycle Mid-Infrared Pulses from Filamentation in Nitrogen

Directory of Open Access Journals (Sweden)

Takao Fuji

2013-02-01

Full Text Available Sub-single-cycle pulses in the mid-infrared (MIR region were generated through a laser-induced filament. The fundamental (ω1 and second harmonic (ω2 output of a 30-fs Ti:sapphire amplifier were focused into nitrogen gas and produce phase-stable broadband MIR pulses (ω0 by using a four-wave mixing process (ω1 + ω1 - ω2 → ω0 through filamentation. The spectrum spread from 400 cm-1 to 5500 cm-1, which completely covered the MIR region. The low frequency components were detected by using an electro-optic sampling technique with a gaseous medium. The efficiency of the MIR pulse generation was very sensitive to the delay between the fundamental and second harmonic pulses. It was revealed that the delay dependence of the efficiency came from the interference between two opposite parametric processes, ω1 + ω1 - ω2 → ω0 and ω2 - ω1 - ω1 → ω0. The pulse duration was measured as 6.9 fs with cross-correlation frequency-resolved optical gating by using four-wave mixing in nitrogen. The carrier-envelope phase of the MIR pulse was passively stabilized. The instability was estimated as 154 mrad rms in 2.5 h.

50-fs pulse generation directly from a colliding-pulse mode-locked Ti:sapphire laser using an antiresonant ring mirror

Science.gov (United States)

Naganuma, Kazunori; Mogi, Kazuo

1991-05-01

50-fs pulses were directly generated from a colliding-pulse mode-locked Ti:sapphire laser. To achieve the colliding-pulse mode locking, a miniature antiresonant ring containing an organic saturable dye jet was employed as the end mirror for the linear cavity laser. Based on measured dispersion of intracavity elements, a prism pair was implemented to control the cavity dispersion. The generated pulses have no linear chirp but do exhibit parabolic instantaneous frequency owing to third-order dispersion introduced by the prism pair.

Spectrally narrowed emissions in 2,5-bis(4-biphenylyl)thiophene crystals pumped by fs laser pulse

International Nuclear Information System (INIS)

Kobayashi, S.; Sasaki, F.; Yanagi, H.; Hotta, S.; Ichikawa, M.; Taniguchi, Y.

2005-01-01

Spectrally narrowed emission (SNE) in 2,5-bis(4-biphenylyl)thiophene (BP1T) crystals is investigated using fs laser pulse. Two different types of narrowing are observed at different vibronic emission bands with increasing pump intensities. Based on their pump intensity dependence and illumination area dependence, we assign the SNE at 20,200 cm -1 (β-band) to amplified spontaneous emission (ASE) and the SNE at 21,600 cm -1 (α-band) to superfluorescence rather than ASE

Generation of spectrally stable 6.5-fs visible pulses via filamentation in krypton

Institute of Scientific and Technical Information of China (English)

Keisuke Kaneshima; Kengo Takeuchi; Nobuhisa Ishii; Jiro Itatani

2016-01-01

We produced 5-μJ, 6.5-fs visible pulses at a repetition rate of 1 kHz using filamentation in a gas cell filled with krypton followed by spectral selection and phase compensation by a combination of dielectric mirrors. The visible pulses have a smooth spectrum from 520 to 650 nm with a shot-to-shot stability in each spectral component of better than 2%(standard deviation). This pulse compression scheme is simple and robust, and can be easily integrated into intense ultrashort-pulse laser systems.

Applications of ultra-short pulsed laser ablation: thin films deposition and fs/ns dual-pulse laser-induced breakdown spectroscopy

International Nuclear Information System (INIS)

Teghil, R; De Bonis, A; Galasso, A; Santagata, A; Albano, G; Villani, P; Spera, D; Parisi, G P

2008-01-01

In this paper, we report a survey of two of the large number of possible practical applications of the laser ablation performed by an ultra-short pulse laser, namely pulsed laser deposition (PLD) and fs/ns dual-pulse laser-induced breakdown spectroscopy (DP-LIBS). These applications differ from those using just longer pulsed lasers as a consequence of the distinctive characteristics of the plasma produced by ultra-short laser beams. The most important feature of this plasma is the large presence of particles with nanometric size which plays a fundamental role in both applications.

500 MW peak power degenerated optical parametric amplifier delivering 52 fs pulses at 97 kHz repetition rate.

Science.gov (United States)

Rothhardt, J; Hädrich, S; Röser, F; Limpert, J; Tünnermann, A

2008-06-09

We present a high peak power degenerated parametric amplifier operating at 1030 nm and 97 kHz repetition rate. Pulses of a state-of-the art fiber chirped-pulse amplification (FCPA) system with 840 fs pulse duration and 410 microJ pulse energy are used as pump and seed source for a two stage optical parametric amplifier. Additional spectral broadening of the seed signal in a photonic crystal fiber creates enough bandwidth for ultrashort pulse generation. Subsequent amplification of the broadband seed signal in two 1 mm BBO crystals results in 41 microJ output pulse energy. Compression in a SF 11 prism compressor yields 37 microJ pulses as short as 52 fs. Thus, pulse shortening of more than one order of magnitude is achieved. Further scaling in terms of average power and pulse energy seems possible and will be discussed, since both concepts involved, the fiber laser and the parametric amplifier have the reputation to be immune against thermo-optical effects.

Repetitively pulsed, double discharge TEA CO/sub 2/ laser

Energy Technology Data Exchange (ETDEWEB)

Hamilton, D C; James, D J; Ramsden, S A

1975-10-01

The design and operation of a repetitively pulsed TEA CO/sub 2/ laser is described. Average powers of up to 400 W at a repetition frequency of 200 pulses/s have been obtained. The system has also been used to provide long pulses (over 20 ..mu..s) and tunable single axial mode pulses.

Characterisation of an optimised high current MgO/Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8.21} composite conductor using pulsed transport currents with pulsed magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Glowacki, B A; Gilewski, A; Rogacki, K; Kursumovic, A; Evetts, J E; Jones, H; Henson, R; Tsukamoto, O

2003-01-15

High temperature superconducting conductors are already used in hybrid magnets to produce fields that enhance the performance of conventional magnets made from A-15 type low temperature superconducting wires. For such applications it is vital that the interdependence of the critical parameters such as critical current versus magnetic field can be mapped under high field and high current conditions. However these superconductors have high critical currents even at fields over 20 T, making accurate measurements difficult due to the thermal and mechanical problems. In this paper, we compare measurements on the fully optimised Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8.21} flat rigid conductors using an innovative pulsed high transport current and pulsed high field technique. We show how analysis of the voltage signal from Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8.21} tape in pulsed conditions may be used to extract the critical current under quasi-stationary conditions.

Self-compression of femtosecond deep-ultraviolet pulses by filamentation in krypton.

Science.gov (United States)

Adachi, Shunsuke; Suzuki, Toshinori

2017-05-15

We demonstrate self-compression of deep-ultraviolet (DUV) pulses by filamentation in krypton. In contrast to self-compression in the near-infrared, that in the DUV is associated with a red-shifted sub-pulse appearing in the pulse temporal profile. The achieved pulse width of 15 fs is the shortest among demonstrated sub-mJ deep-ultraviolet pulses.

Formation of metal nanoparticles of various sizes in plasma plumes produced by Ti:sapphire laser pulses

International Nuclear Information System (INIS)

Chakravarty, U.; Naik, P. A.; Mukherjee, C.; Kumbhare, S. R.; Gupta, P. D.

2010-01-01

In this paper, an experimental study on generation of nanoparticle various sizes using Ti:sapphire laser pulses, is reported. Nanoparticle formation in plasma plumes of metals like silver and copper, expanding in vacuum, has been studied using stretched pulses of 300 ps duration [subnanoseconds (sub-ns)] from a Ti:sapphire laser. It has been compared with the nanoparticle formation (of the same materials) when compressed pulses of 45 fs duration were used under similar focusing conditions. Nanoparticle formation is observed at intensities as high as 2x10 16 W/cm 2 . The structural analysis of the nanoparticle deposition on a silicon substrate showed that, using 45 fs pulses, smaller nanoparticles of average size ∼20 nm were generated, whereas on using the sub-ns pulses, larger particles were produced. Also, the visible light transmission and reflection from the nanoparticle film of Ag on glass substrate showed surface plasmon resonance (SPR). The SPR curves of the films of nanoparticles deposited by femtosecond pulses were always broader and reflection/transmission was always smaller when compared with the films formed using the sub-ns pulses, indicating smaller size particle formation by ultrashort pulses. Thus, it has been demonstrated that variation in the laser pulse duration of laser offers a simple tool for varying the size of the nanoparticles generated in plasma plumes.

The influence of laser pulse duration and energy on ICP-MS signal intensity, elemental fractionation, and particle size distribution in NIR fs-LA-ICP-MS

Science.gov (United States)

Diwakar, Prasoon K.; Harilal, Sivanandan S.; LaHaye, Nicole L.; Hassanein, Ahmed; Kulkarni, Pramod

2015-01-01

Laser parameters, typically wavelength, pulse width, irradiance, repetition rate, and pulse energy, are critical parameters which influence the laser ablation process and thereby influence the LA-ICP-MS signal. In recent times, femtosecond laser ablation has gained popularity owing to the reduction in fractionation related issues and improved analytical performance which can provide matrix-independent sampling. The advantage offered by fs-LA is due to shorter pulse duration of the laser as compared to the phonon relaxation time and heat diffusion time. Hence the thermal effects are minimized in fs-LA. Recently, fs-LA-ICP-MS demonstrated improved analytical performance as compared to ns-LA-ICP-MS, but detailed mechanisms and processes are still not clearly understood. Improvement of fs-LA-ICP-MS over ns-LA-ICP-MS elucidates the importance of laser pulse duration and related effects on the ablation process. In this study, we have investigated the influence of laser pulse width (40 fs to 0.3 ns) and energy on LA-ICP-MS signal intensity and repeatability using a brass sample. Experiments were performed in single spot ablation mode as well as rastering ablation mode to monitor the Cu/Zn ratio. The recorded ICP-MS signal was correlated with total particle counts generated during laser ablation as well as particle size distribution. Our results show the importance of pulse width effects in the fs regime that becomes more pronounced when moving from femtosecond to picosecond and nanosecond regimes. PMID:26664120

Interaction mechanisms of cavitation bubbles induced by spatially and temporally separated fs-laser pulses.

Directory of Open Access Journals (Sweden)

Nadine Tinne

Full Text Available The emerging use of femtosecond lasers with high repetition rates in the MHz regime together with limited scan speed implies possible mutual optical and dynamical interaction effects of the individual cutting spots. In order to get more insight into the dynamics a time-resolved photographic analysis of the interaction of cavitation bubbles is presented. Particularly, we investigated the influence of fs-laser pulses and their resulting bubble dynamics with various spatial as well as temporal separations. Different time courses of characteristic interaction effects between the cavitation bubbles were observed depending on pulse energy and spatio-temporal pulse separation. These ranged from merely no interaction to the phenomena of strong water jet formation. Afterwards, the mechanisms are discussed regarding their impact on the medical application of effective tissue cutting lateral to the laser beam direction with best possible axial precision: the mechanical forces of photodisruption as well as the occurring water jet should have low axial extend and a preferably lateral priority. Furthermore, the overall efficiency of energy conversion into controlled mechanical impact should be maximized compared to the transmitted pulse energy and unwanted long range mechanical side effects, e.g. shock waves, axial jet components. In conclusion, these experimental results are of great importance for the prospective optimization of the ophthalmic surgical process with high-repetition rate fs-lasers.

A 20fs synchronization system for lasers and cavities in accelerators and FELs

Science.gov (United States)

Wilcox, R. B.; Byrd, J. M.; Doolittle, L. R.; Huang, G.; Staples, J. W.

2010-02-01

A fiber-optic RF distribution system has been developed for synchronizing lasers and RF plants in short pulse FELs. Typical requirements are 50-100fs rms over time periods from 1ms to several hours. Our system amplitude modulates a CW laser signal, senses fiber length using an interferometer, and feed-forward corrects the RF phase digitally at the receiver. We demonstrate less than 15fs rms error over 12 hours, between two independent channels with a fiber path length difference of 200m and transmitting S-band RF. The system is constructed using standard telecommunications components, and uses regular telecom fiber.

Subfemtosecond pulse generation by cascade-stimulated Raman scattering with modulated Raman excitation

International Nuclear Information System (INIS)

Wu Kun; Wu Jian; Zeng Heping

2003-01-01

Subfemtosecond (sub-fs) pulses can be generated by cascade-stimulated Raman scattering in a Raman medium with modulated Raman excitations, driven by two sufficiently intense laser beams, one of which is amplitude modulated. The nonadiabatic Raman interaction establishes a strong modulated Raman coherence, which supports compression of the generated broadband Raman sidebands to a train of sub-fs pulses regardless of whether the carrier frequencies of the driving lasers are tuned above, below or on two-photon Raman resonance. (letter to the editor)

256 fs, 2 nJ soliton pulse generation from MoS2 mode-locked fiber laser

Science.gov (United States)

Jiang, Zike; Chen, Hao; Li, Jiarong; Yin, Jinde; Wang, Jinzhang; Yan, Peiguang

2017-12-01

We demonstrate an Er-doped fiber laser (EDFL) mode-locked by a MoS2 saturable absorber (SA), delivering a 256 fs, 2 nJ soliton pulse at 1563.4 nm. The nonlinear property of the SA prepared by magnetron sputtering deposition (MSD) is measured with a modulation depth (MD) of ∼19.48% and a saturable intensity of 4.14 MW/cm2. To the best of our knowledge, the generated soliton pulse has the highest pulse energy of 2 nJ among the reported mode-locked EDFLs based on transition metal dichalcogenides (TMDs). Our results indicate that MSD-grown SAs could offer an exciting platform for high pulse energy and ultrashort pulse generation.

A search for the sulphur hexafluoride cation with intense, few cycle laser pulses

Energy Technology Data Exchange (ETDEWEB)

Dota, Krithika; Mathur, Deepak, E-mail: atmol1@tifr.res.in [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India); Centre for Atomic and Molecular Physics, Manipal University, Manipal 576 104 (India); Dharmadhikari, Aditya K. [Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400 005 (India); Dharmadhikari, Jayashree A. [Centre for Atomic and Molecular Physics, Manipal University, Manipal 576 104 (India); Patra, Kaustuv; Tiwari, Ashwani K. [Indian Institute of Science Education and Research - Kolkata, Mohanpur 741 252 (India)

2013-11-21

It is well established that upon ionization of sulphur hexafluoride, the SF{sub 6}{sup +} ion is never observed in mass spectra. Recent work with ultrashort intense laser pulses has offered indications that when strong optical field are used, the resulting “bond hardening” can induce changes in the potential energy surfaces of molecular cations such that molecular ions that are normally unstable may, indeed, become metastable enough to enable their detection by mass spectrometry. Do intense, ultrashort laser pulses permit formation of SF{sub 6}{sup +}? We have utilized intense pulses of 5 fs, 11 fs, and 22 fs to explore this possibility. Our results are negative: no evidence is discovered for SF{sub 6}{sup +}. However, multiply charged sulphur and fluorine ions from highly charged SF{sub 6}{sup q+} ions are observed that enable us to resolve the controversy regarding the kinetic energy release accompanying formation of F{sup +} fragment ions. Quantum chemical computations of field-distorted potential energy curves of SF{sub 6} and its molecular ion enable us to rationalize our non-observation of SF{sub 6}{sup +}. Our findings have implications for high harmonic generation from SF{sub 6} in the few-cycle regime.

650-nJ pulses from a cavity-dumped Yb:fiber-pumped ultrafast optical parametric oscillator

Science.gov (United States)

Lamour, Tobias P.; Reid, Derryck T.

2011-08-01

Sub-250-fs pulses with energies of up to 650 nJ and peak powers up to 2.07 MW were generated from a cavity-dumped optical parametric oscillator, synchronously-pumped at 15.3 MHz with sub-400-fs pulses from an Yb:fiber laser. The average beam quality factor of the dumped output was M2 ~1.2 and the total relative-intensity noise was 8 mdBc, making the system a promising candidate for ultrafast laser inscription of infrared materials.

Research for robust femtosecond chirped-pulse amplification laser with an identical positive dispersive media as pulse stretcher and compressor

International Nuclear Information System (INIS)

Akahane, Yutaka; Ogawa, Kanade; Tsuji, Koichi; Aoyama, Makoto; Yamakawa, Koichi

2011-01-01

We have proposed and demonstrated a simple and robust femtosecond optical-parametric chirped-pulse amplification scheme in which an even order dispersion of an idler pulse is compensated by passing through an identical positive dispersive material used for temporal stretching a signal pulse. By compressing the idler pulses having a negatively chirp in this manner, high power sub-100 fs pulses were successfully obtained with only a transparent glass block used for the stretcher and compressor. (author)

Cavity-less sub-picosecond pulse generation for the demultiplexing of a 640 Gbaud OTDM signal

DEFF Research Database (Denmark)

Kong, Deming; Guan, Pengyu; Hu, Hao

2015-01-01

A 703 fs cavity-less pulse source based on pulse carving and pulse compression is demonstrated and utilized for demultiplexing a 640 Gbaud OTDM signal. Timing jitter is found to be the main limiting factor....

Toward sub-femtosecond pump-probe experiments: a dispersionless autocorrelator with attosecond resolution

Energy Technology Data Exchange (ETDEWEB)

Constant, E.; Mevel, E.; Zair, A.; Bagnoud, V.; Salin, F. [Bordeaux-1 Univ., Talence (FR). Centre Lasers Intenses et Applications (CELIA)

2001-07-01

We designed a dispersionless autocorrelator with a sub-femtosecond resolution suitable for the characterization of ultrashort X-UV pulses. We present a proof of feasibility experiment with 11 fs infrared pulses. (orig.)

Effect of Ta buffer and NiFe seed layers on pulsed-DC magnetron sputtered Ir{sub 20}Mn{sub 80}/Co{sub 90}Fe{sub 10} exchange bias

Energy Technology Data Exchange (ETDEWEB)

Oksuezoglu, Ramis Mustafa, E-mail: rmoksuzoglu@anadolu.edu.t [University of Anadolu, Faculty of Engineering and Architecture, Department of Materials Sciences and Engineering, Iki Eyluel Campus, 26555 Eskisehir (Turkey); Yildirim, Mustafa; Cinar, Hakan [University of Anadolu, Faculty of Engineering and Architecture, Department of Materials Sciences and Engineering, Iki Eyluel Campus, 26555 Eskisehir (Turkey); Hildebrandt, Erwin; Alff, Lambert [Department of Materials Sciences, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany)

2011-07-15

A systematic investigation has been done on the correlation between texture, grain size evolution and magnetic properties in Ta/Ni{sub 81}Fe{sub 19}/Ir{sub 20}Mn{sub 80}/Co{sub 90}Fe{sub 10}/Ta exchange bias in dependence of Ta buffer and NiFe seed layer thickness in the range of 2-10 nm, deposited by pulsed DC magnetron sputtering technique. A strong dependence of <1 1 1> texture on the Ta/NiFe thicknesses was found, where the reducing and increasing texture was correlated with exchange bias field and unidirectional anisotropy energy constant at both NiFe/IrMn and IrMn/CoFe interfaces. However, a direct correlation between average grain size in IrMn and H{sub ex} and H{sub c} was not observed. L1{sub 2} phase IrMn{sub 3} could be formed by thickness optimization of Ta/NiFe layers by deposition at room temperature, for which the maximum exchange coupling parameters were achieved. We conclude finally that the coercivity is mainly influenced by texture induced interfacial effects at NiFe/IrMn/CoFe interfaces developing with Ta/NiFe thicknesses. - Research highlights: We discussed the influence of Ta/NiFe thicknesses on structure and grain size in AF layer and texture. A direct correlation between the <1 1 1> texture and exchange coupling was found. A direct relation between average grain size and H{sub ex} and H{sub c} was not observed. L1{sub 2} phase IrMn{sub 3} was formed by deposition at room temperature for Ta (5-6 nm)/NiFe (6-8 nm). We conclude that the coercivity is influenced by order/disorder at NiFe/IrMn/CoFe interfaces.

Fundus oculi pigmentation studies simulating the fs-LASIK process Fundus oculi pigmentation studies simulating the fs-LASIK process

Science.gov (United States)

Sander, M.; Minet, O.; Zabarylo, U.; Müller, M.; Tetz, M. R.

2012-06-01

The femtosecond-laser in situ keratomileusis (fs-LASIK) technique has successfully entered the refractive surgery market to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses based on photodisruption. The laser pulses in the near infrared range (NIR) generate a laser-induced breakdown (LIOB) in the cornea. By propagating through the eye, a certain amount of the pulse is deposited in the cornea and the remaining energy interacts with the strong absorbing tissue behind. Due to the absorption by the retinal pigment epithelium and the transfer of the thermal energy to surrounding tissue, the transmitted energy can induce damage to the retina. The aim of this project was to find out the threshold influences concerning the tissue and the correlation between the results of the macroscopical appraisal and the fundus oculi pigmentation by simulating the fs-LASIK procedure with two various laser systems in the continuous wave (CW) and fs-regime. Therefore ex-vivo determinations were carried out macroscopically and histopathologically on porcine tissue.

On-chip nanostructuring and impedance trimming of transparent and flexible ITO electrodes by laser induced coherent sub-20 nm cuts

Energy Technology Data Exchange (ETDEWEB)

Afshar, Maziar, E-mail: m.afshar@lmm.uni-saarland.de [Lab for Micromechanics, Microfluidics, and Microactuators, Saarland University, Saarbrücken D-66123 (Germany); Leber, Moritz [Lab for Micromechanics, Microfluidics, and Microactuators, Saarland University, Saarbrücken D-66123 (Germany); Poppendieck, Wigand [Department of Medical Engineering & Neuroprosthetics, Fraunhofer Institute for Biomedical Engineering, St. Ingbert D-66386 (Germany); König, Karsten [Lab for Biophotonics and Laser Technology, Saarland University, Saarbrücken D-66123 (Germany); Seidel, Helmut; Feili, Dara [Lab for Micromechanics, Microfluidics, and Microactuators, Saarland University, Saarbrücken D-66123 (Germany)

2016-01-01

Graphical abstract: - Highlights: • A novel method to make sub-20 nm nanopatterning in ITO thin films by laser writing. • A novel way to functionalize ITO bio-electrodes to yield near-field polarizing feature. • A basic characterization of ITO electrodes was performed by impedance spectroscopy. • Presentation of simulations and possible theoretical approaches to explain the results. - Abstract: In this work, the effect of laser-induced nanostructuring of transparent indium tin oxide (ITO) electrodes on flexible glass is investigated. Multi-electrode arrays (MEA) for electrical and optical characterization of biological cells were fabricated using standard MEMS technologies. Optimal sputter parameters concerning oxygen flow, sputter power and ambient pressure for ITO layers with both good optical and electrical properties were determined. Afterwards, coherent sub-20 nm wide and 150 nm deep nanocuts of many micrometers in length were generated within the ITO electrodes by a sub-15 femtosecond (fs) pulsed laser. The influence of laser processing on the electrical and optical properties of electrodes was investigated. The electrochemical impedance of the manufactured electrodes was measured before and after laser modification using electrochemical impedance spectroscopy. A small reduction in electrode impedance was observed. These nanostructured electrodes show also polarizing effects by the visible spectrum.

Ultrafast photodynamics of pyrazine in the vacuum ultraviolet region studied by time-resolved photoelectron imaging using 7.8-eV pulses

Energy Technology Data Exchange (ETDEWEB)

Horio, Takuya; Suzuki, Yoshi-ichi; Suzuki, Toshinori, E-mail: suzuki@kuchem.kyoto-u.ac.jp [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-Ku, Kyoto 606-8502 (Japan)

2016-07-28

The ultrafast electronic dynamics of pyrazine (C{sub 4}N{sub 2}H{sub 4}) were studied by time-resolved photoelectron imaging (TRPEI) using the third (3ω, 4.7 eV) and fifth harmonics (5ω, 7.8 eV) of a femtosecond Ti:sapphire laser (ω). Although the photoionization signals due to the 5ω − 3ω and 3ω − 5ω pulse sequences overlapped near the time origin, we have successfully extracted their individual TRPEI signals using least squares fitting of the observed electron kinetic energy distributions. When the 5ω pulses preceded the 3ω pulses, the 5ω pulses predominantly excited the S{sub 4} (ππ{sup *}, {sup 1}B{sub 1u}+{sup 1}B{sub 2u}) state. The photoionization signal from the S{sub 4} state generated by the time-delayed 3ω pulses was dominated by the D{sub 3}({sup 2}B{sub 2g})←S{sub 4} photoionization process and exhibited a broad electron kinetic energy distribution, which rapidly downshifted in energy within 100 fs. Also observed were the photoionization signals for the 3s, 3p{sub z}, and 3p{sub y} members of the Rydberg series converging to D{sub 0}({sup 2}A{sub g}). The Rydberg signals appeared immediately within our instrumental time resolution of 27 fs, indicating that these states are directly photoexcited from the ground state or populated from S{sub 4} within 27 fs. The 3s, 3p{sub z}, and 3p{sub y} states exhibited single exponential decay with lifetimes of 94 ± 2, 89 ± 2, and 58 ± 1 fs, respectively. With the reverse pulse sequence of 3ω − 5ω, the ultrafast internal conversion (IC) from S{sub 2}(ππ{sup *}) to S{sub 1}(nπ{sup *}) was observed. The decay associated spectrum of S{sub 2} exhibited multiple bands ascribed to D{sub 0}, D{sub 1}, and D{sub 3}, in agreement with the 3ω-pump and 6ω-probe experiment described in our preceding paper [T. Horio et al., J. Chem. Phys. 145, 044306 (2016)]. The electron kinetic energy and angular distributions from S{sub 1} populated by IC from S{sub 2} are also discussed.

Ablation of silicon with bursts of femtosecond laser pulses

Science.gov (United States)

Gaudiuso, Caterina; Kämmer, Helena; Dreisow, Felix; Ancona, Antonio; Tünnermann, Andreas; Nolte, Stefan

2016-03-01

We report on an experimental investigation of ultrafast laser ablation of silicon with bursts of pulses. The pristine 1030nm-wavelength 200-fs pulses were split into bursts of up to 16 sub-pulses with time separation ranging from 0.5ps to 4080ps. The total ablation threshold fluence was measured depending on the burst features, finding that it strongly increases with the number of sub-pulses for longer sub-pulse delays, while a slowly increasing trend is observed for shorter separation time. The ablation depth per burst follows two different trends according to the time separation between the sub-pulses, as well as the total threshold fluence. For delays shorter than 4ps it decreases with the number of pulses, while for time separations longer than 510ps, deeper craters were achieved by increasing the number of subpulses in the burst, probably due to a change of the effective penetration depth.

High-energy infrared femtosecond pulses generated by dual-chirped optical parametric amplification.

Science.gov (United States)

Fu, Yuxi; Takahashi, Eiji J; Midorikawa, Katsumi

2015-11-01

We demonstrate high-energy infrared femtosecond pulse generation by a dual-chirped optical parametric amplification (DC-OPA) scheme [Opt. Express19, 7190 (2011)]. By employing a 100 mJ pump laser, a signal pulse energy exceeding 20 mJ at a wavelength of 1.4 μm was achieved before dispersion compensation. A total output energy of 33 mJ was recorded. Under a further energy scaling condition, the signal pulse was compressed to an almost transform-limited duration of 27 fs using a fused silica prism compressor. Since the DC-OPA scheme is efficient and energy scalable, design parameters for obtaining 100 mJ level infrared pulses are presented, which are suitable as driver lasers for the energy scaling of high-order harmonic generation with sub-keV photon energy.

Analysis of laser energy deposition leading to damage and ablation of HfO{sub 2} and Nb{sub 2}O{sub 5} single layers submitted to 500 fs pulses at 1030 and 343 nm

Energy Technology Data Exchange (ETDEWEB)

Douti, Dam-Be; Begou, Thomas; Lemarchand, Fabien; Lumeau, Julien; Commandre, Mireille; Gallais, Laurent [Aix-Marseille Universite, CNRS, Centrale Marseille, Institut Fresnel UMR 7249, Marseille (France)

2016-07-15

Laser- induced damage thresholds and morphologies of laser ablated sites on dielectric thin films are studied based on experiments and simulations. The films are single layers of hafnia and niobia deposited on fused silica substrates with a magnetron sputtering technique. Laser experiments are conducted with 500 fs pulses at 1030 and 343 nm, and the irradiated sites are characterized with optical profilometry and scanning electron microscopy. The results, i.e., LIDT and damage morphologies, are compared to simulations of energy deposition in the films based on the single rate equation for electron excitation, taking into account transient optical properties of the films during the pulse. The results suggest that a critical absorbed energy as a damage criterion gives consistent results both with the measured LIDT and the observed damage morphologies at fluences close to the damage threshold. Based on the numerical and experimental results, the determined LIDT evolution with the wavelength is described as nearly constant in the near-infrared region, and as rapidly decreasing with laser wavelength in the visible and near-ultraviolet regions. (orig.)

40-fs hydrogen Raman laser

Energy Technology Data Exchange (ETDEWEB)

Didenko, N V; Konyashchenko, A V; Kostryukov, P V; Losev, L L; Pazyuk, V S [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Tenyakov, S Yu [Avesta Ltd., Troitsk, Moscow (Russian Federation); Molchanov, V Ya; Chizhikov, S I; Yushkov, K B [National University of Science and Technology ' MISIS' , Acoustooptical Research Center, Moscow (Russian Federation)

2015-12-31

40-fs first Stokes pulses at a wavelength of 1.2 μm were generated in a hydrogen SRS-converter pumped by orthogonally polarised double chirped pulses of a Ti : sapphire laser. To obtain a Stokes pulse close to a transform-limited one, a programmed acousto-optic dispersive delay line was placed between the master oscillator and regenerative amplifier. The energy efficiency of Stokes radiation conversion reached 22%. (lasers)

40-fs hydrogen Raman laser

International Nuclear Information System (INIS)

Didenko, N V; Konyashchenko, A V; Kostryukov, P V; Losev, L L; Pazyuk, V S; Tenyakov, S Yu; Molchanov, V Ya; Chizhikov, S I; Yushkov, K B

2015-01-01

40-fs first Stokes pulses at a wavelength of 1.2 μm were generated in a hydrogen SRS-converter pumped by orthogonally polarised double chirped pulses of a Ti : sapphire laser. To obtain a Stokes pulse close to a transform-limited one, a programmed acousto-optic dispersive delay line was placed between the master oscillator and regenerative amplifier. The energy efficiency of Stokes radiation conversion reached 22%. (lasers)

Phase transformations in the rapidly solidified Ti{sub 40}Zr{sub 20}Hf{sub 20}Pd{sub 20} alloy

Energy Technology Data Exchange (ETDEWEB)

Chen, N. [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Yao Kefu [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: kfyao@tsinghua.edu.cn; Louzguine-Luzgin, D.V. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Qiu Shengbao [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Ranganathan, S. [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India); Inoue, A. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2007-10-15

We report that an approximant phase was initially obtained in amorphous Ti{sub 40}Zr{sub 20}Hf{sub 20}Pd{sub 20} alloy. In the initial stage of the devitrification process, the approximant phase transforms into an icosahedral (I) phase with a high thermal stability while the cF96 Zr{sub 2}Ni-type (space group Fd3-bar m with a=1.25nm and 96 atoms cell{sup -1}) particles precipitate from the amorphous matrix. Eventually the I phase grows to several hundred nanometers when annealed at about 1000K and then transforms into the Zr{sub 2}Ni-type phase with an endothermic reaction.

Wave-packet dynamics in alkaline dimers. Investigation and control through coherent excitation with fs-pulses

International Nuclear Information System (INIS)

Sauer, F.N.B.

2007-01-01

During my PhD thesis I investigated alkaline dimers with coherent control in a molecular beam as well as with pump-probe spectroscopy in a magneto-optical trap (MOT). The aim of the coherent control experiments were the isotope selective ionization with phase- and amplitude-shaped fs-pulses. Chapter 4 described the gained results of isotope selective ionization of NaK and KRb in a molecular beam by using different pulse formers. For the NaK dimer was the reached optimization factor R Ph and Ampl 770 =R max /R min =25 between maximization and minimization of the isotopomer ratio ( 23 Na 39 K) + /( 23 Na 41 K) + with phase and amplitude modulation of the fs-pulse with a central wavelength of λ=770 nm. From the electronic ground-state X(1) 1 Σ + ;ν''=0 transfers a one-photon-excitation population in the first excited A(2) 1 Σ + state. The coherent control experiment on KRb was used to maximize and minimize the isotopomer ratio ( 124 KRb) + /( 126 KRb) + . It was the first coherent control experiment with a spectral resolution of 1.84 cm -1 /Pixel. For the phase and amplitude optimization was the received optimization factor between minimization and maximization of the isotopomer ratio R Ph and Ampl =R max /R min =7 at a central wavelength of 840 nm. The results showed a stepwise excitation process from the electronic ground-state in the first excited (2) 1 Σ + state with a further excitation, that is possible over three resonant energy potential curves into the ionic ground-state. In the second part of my thesis I realized pump-probe spectroscopy of Rb 2 dimers in a dark SPOT. (orig.)

Sub-critical pulsed neutron experiments with uranyl nitrate solutions in spherical geometry

International Nuclear Information System (INIS)

Gurin, Victor N.; Ryazanov, Boris G.; Sviridov, Victor I.; Volnistov, Vladimir V.

2003-01-01

The pulse source method is used to study homogeneous solution assemblies. Three sets of sub-critical pulse experiments with spherical tanks filled with water solution of uranyl nitrate (90% enrichment) were carried out at the RF-GS facility, Obninsk, Russia. Seven spherical tanks with the volume within the range of 1.29 L to 19.8 L were used in the experiments. Three uranium concentrations were studied, i.e. 20.7, 29.6 and 37.5 g/L. The sub-critical experiments were analyzed with the MCNP 4A code based on the Monte-Carlo method, and with ENDF/B-V library. (author)

Sub?40?fs, 1060?nm Yb?fiber laser enhances penetration depth in nonlinear optical microscopy of human skin

OpenAIRE

Balu, Mihaela; Saytashev, Ilyas; Hou, Jue; Dantus, Marcos; Tromberg, Bruce J.

2015-01-01

© 2015 The Authors. Advancing the practical utility of nonlinear optical microscopy requires continued improvement in imaging depth and contrast. We evaluated second-harmonic generation (SHG) and third-harmonic generation images from ex vivo human skin and showed that a sub-40 fs, 1060-nm Yb-fiber laser can enhance SHG penetration depth by up to 80% compared to a > 100 fs, 800 nm Ti:sapphire source. These results demonstrate the potential of fiber-based laser systems to address a key perform...

Optical reprogramming of human somatic cells using ultrashort Bessel-shaped near-infrared femtosecond laser pulses

Science.gov (United States)

Uchugonova, Aisada; Breunig, Hans Georg; Batista, Ana; König, Karsten

2015-11-01

We report a virus-free optical approach to human cell reprogramming into induced pluripotent stem cells with low-power nanoporation using ultrashort Bessel-shaped laser pulses. Picojoule near-infrared sub-20 fs laser pulses at a high 85 MHz repetition frequency are employed to generate transient nanopores in the membrane of dermal fibroblasts for the introduction of four transcription factors to induce the reprogramming process. In contrast to conventional approaches which utilize retro- or lentiviruses to deliver genes or transcription factors into the host genome, the laser method is virus-free; hence, the risk of virus-induced cancer generation limiting clinical application is avoided.

Development of optical parametric chirped-pulse amplifiers and their applications

Energy Technology Data Exchange (ETDEWEB)

Ishii, Nobuhisa

2006-11-21

In this work, optical pulse amplification by parametric chirped-pulse amplification (OPCPA) has been applied to the generation of high-energy, few-cycle optical pulses in the near-infrared (NIR) and infrared (IR) spectral regions. Amplification of such pulses is ordinarily difficult to achieve by existing techniques of pulse amplification based on standard laser gain media followed by external compression. Potential applications of few-cycle pulses in the IR have also been demonstrated. The NIR OPCPA system produces 0.5-terawatt (10 fs,5 mJ) pulses by use of noncollinearly phase-matched optical parametric amplification and a down-chirping stretcher and up-chirping compressor pair. An IR OPCPA system was also developed which produces 20-gigawatt (20 fs,350 {mu}J) pulses at 2.1 {mu}m. The IR seed pulse is generated by optical rectification of a broadband pulse and therefore it exhibits a self-stabilized carrier-envelope phase (CEP). In the IR OPCPA a common laser source is used to generate the pump and seed resulting in an inherent sub-picosecond optical synchronization between the two pulses. This was achieved by use of a custom-built Nd:YLF picosecond pump pulse amplifier that is directly seeded with optical pulses from a custom-built ultrabroadband Ti:sapphire oscillator. Synchronization between the pump and seed pulses is critical for efficient and stable amplification. Two spectroscopic applications which utilize these unique sources have been demonstrated. First, the visible supercontinuum was generated in a solid-state media by the infrared optical pulses and through which the carrier-envelope phase (CEP) of the driving pulse was measured with an f-to-3f interferometer. This measurement confirms the self-stabilization mechanism of the CEP in a difference frequency generation process and the preservation of the CEP during optical parametric amplification. Second, high-order harmonics with energies extending beyond 200 eV were generated with the few

Fundus oculi pigmentation studies simulating the fs-LASIK process

Energy Technology Data Exchange (ETDEWEB)

Sander, M; Tetz, M R [Berlin Eye Research Institute, Alt Moabit 101b, 10559 Berlin (Germany); Minet, O; Zabarylo, U [Charite Centrum 6, Arbeitsgruppe Medizinische Physik/Optische Diagnostik, Fabeckstrasse 60–62, 14195 Berlin (Germany); Mueller, M [Augenklinik Ahaus, Am Schlossgraben 13, 48683 Ahaus (Germany)

2012-06-15

The femtosecond-laser in situ keratomileusis (fs-LASIK) technique has successfully entered the refractive surgery market to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses based on photodisruption. The laser pulses in the near infrared range (NIR) generate a laser-induced breakdown (LIOB) in the cornea. By propagating through the eye, a certain amount of the pulse is deposited in the cornea and the remaining energy interacts with the strong absorbing tissue behind. Due to the absorption by the retinal pigment epithelium and the transfer of the thermal energy to surrounding tissue, the transmitted energy can induce damage to the retina. The aim of this project was to find out the threshold influences concerning the tissue and the correlation between the results of the macroscopical appraisal and the fundus oculi pigmentation by simulating the fs-LASIK procedure with two various laser systems in the continuous wave (CW) and fs-regime. Therefore ex-vivo determinations were carried out macroscopically and histopathologically on porcine tissue.

Fundus oculi pigmentation studies simulating the fs-LASIK process

International Nuclear Information System (INIS)

Sander, M; Tetz, M R; Minet, O; Zabarylo, U; Mueller, M

2012-01-01

The femtosecond-laser in situ keratomileusis (fs-LASIK) technique has successfully entered the refractive surgery market to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses based on photodisruption. The laser pulses in the near infrared range (NIR) generate a laser-induced breakdown (LIOB) in the cornea. By propagating through the eye, a certain amount of the pulse is deposited in the cornea and the remaining energy interacts with the strong absorbing tissue behind. Due to the absorption by the retinal pigment epithelium and the transfer of the thermal energy to surrounding tissue, the transmitted energy can induce damage to the retina. The aim of this project was to find out the threshold influences concerning the tissue and the correlation between the results of the macroscopical appraisal and the fundus oculi pigmentation by simulating the fs-LASIK procedure with two various laser systems in the continuous wave (CW) and fs-regime. Therefore ex-vivo determinations were carried out macroscopically and histopathologically on porcine tissue

Radiation influencing of the extraction properties of the CyMe{sub 4}-BTBP and CyMe{sub 4}-BTPhen solvents with FS-13

Energy Technology Data Exchange (ETDEWEB)

Konde, J.; Distler, P.; John, J. [Department of Nuclear Chemistry, Czech Technical University in Prague, BGehova 7, 11519 Prague 1 (Czech Republic); Svehla, J.; Gruner, B.; Belcicka, Z. [Institute of Inorganic Chemistry, Academy of Sciences of the Czech Republic, 250 68 Rez near Prague (Czech Republic)

2016-07-01

The radiolytic stability of two ligands, CyMe4-BTBP and CyMe4-BTPhen in system with the FS-13 (phenyl trifluoromethyl sulfone) diluent was investigated under irradiation by accelerated electrons to study impact of the degradation products on the separation process efficiency and safety. Irradiation experiments were carried out up to the absorbed dose of 200 kGy. The irradiated samples were analysed by HPLC for the degree of extractant degradation. In addition, the effect of the presence of HNO{sub 3} during the irradiation was studied. Extraction properties of the irradiated solvents were evaluated and compared with the extraction properties of non-irradiated solvents to assess the impact of the degradation products on extractions properties. The results obtained show that the stabilities of these ligands are higher in FS-13 than in the cyclohexanone-type solvents. The extraction properties are significantly influenced by degradation products contained in these systems. Surprisingly, both the distribution ratios for americium and europium, and the Am/Eu separation factor increase with the absorbed dose for the system withCyMe{sub 4}-BTPhen in FS-13. Obviously, the degradation products of this ligand are efficient extractants too. In the next phase, an attempt will be done to identify the main degradation products, synthesise them and study their extraction properties. (authors)

Power scaling of supercontinuum seeded megahertz-repetition rate optical parametric chirped pulse amplifiers.

Science.gov (United States)

Riedel, R; Stephanides, A; Prandolini, M J; Gronloh, B; Jungbluth, B; Mans, T; Tavella, F

2014-03-15

Optical parametric chirped-pulse amplifiers with high average power are possible with novel high-power Yb:YAG amplifiers with kW-level output powers. We demonstrate a compact wavelength-tunable sub-30-fs amplifier with 11.4 W average power with 20.7% pump-to-signal conversion efficiency. For parametric amplification, a beta-barium borate crystal is pumped by a 140 W, 1 ps Yb:YAG InnoSlab amplifier at 3.25 MHz repetition rate. The broadband seed is generated via supercontinuum generation in a YAG crystal.

Effect of iron content on the structure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25} and (AlTi){sub 60-x}Ni{sub 20}Cu{sub 20}Fe{sub x} (x=15, 20) high-entropy alloys

Energy Technology Data Exchange (ETDEWEB)

Fazakas, É., E-mail: eva.fazakas@bayzoltan.hu [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Wigner Research Center for Physics, Hungarian Academy of Sciences, H-1525, P.O.B. 49 (Hungary); Bay Zoltán Nonprofit Ltd., For Applied Research H-1116 Budapest, Fehérvári út 130 (Hungary); Zadorozhnyy, V. [National University of Science and Technology «MISIS», Leninsky prosp., 4, Moscow 119049 (Russian Federation); Louzguine-Luzgin, D.V. [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2015-12-15

Highlights: • Three new refractory alloys namely: Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20}, were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}C{sub u25} Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys are relatively hard and ductile. Being heat treated at 973 K the Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

Interaction of intense femtosecond laser pulses with high-Z solids

International Nuclear Information System (INIS)

Zhidkov, A.; Sasaki, Akira; Utsumi, Takayuki; Fukumoto, Ichirou; Tajima, Toshiki; Yoshida, Masatake; Kondo, Kenichi

2000-01-01

A plasma irradiated by an intense very short pulse laser can be an ultimate high brightness source of incoherent inner-shell X-ray emission of 1-30 keV. The recently developed 100 TW, 20 fs laser facility in JAERI can make considerable enhancement here. To show this a hybrid model combining hydrodynamics and collisional particle-in-cell simulations is applied. Effect of laser prepulse on the interaction of an intense s-polarized femtosecond, ∼20/40 fs, laser pulse with high-Z solid targets is studied. A new absorption mechanism originating from the interaction of the laser pulse with plasma waves excited by the relativistic component of the Lorentz force is found to increase the absorption rate over 30% even for a very short laser pulse. The obtained hot electron temperature exceeds 0.5-1 MeV at optimal conditions for absorption. Results of the simulation for lower laser pulse intensities are in good agreement with the experimental measurements of the hot electron energy distribution. (author)

Generation of 103 fs mode-locked pulses by a gain linewidth-variable Nd,Y:CaF2 disordered crystal.

Science.gov (United States)

Qin, Z P; Xie, G Q; Ma, J; Ge, W Y; Yuan, P; Qian, L J; Su, L B; Jiang, D P; Ma, F K; Zhang, Q; Cao, Y X; Xu, J

2014-04-01

We have demonstrated a diode-pumped passively mode-locked femtosecond Nd,Y:CaF2 disordered crystal laser for the first time to our knowledge. By choosing appropriate Y-doping concentration, a broad fluorescence linewidth of 31 nm has been obtained from the gain linewidth-variable Nd,Y:CaF2 crystal. With the Nd,Y:CaF2 disordered crystal as gain medium, the mode-locked laser generated pulses with pulse duration as short as 103 fs, average output power of 89 mW, and repetition rate of 100 MHz. To our best knowledge, this is the shortest pulse generated from Nd-doped crystal lasers so far. The research results show that the Nd,Y:CaF2 disordered crystal will be a potential alternative as gain medium of repetitive chirped pulse amplification for high-peak-power lasers.

Standard measurement procedures for the characterization of fs-laser optical components

Science.gov (United States)

Starke, Kai; Ristau, Detlev; Welling, Herbert

2003-05-01

Ultra-short pulse laser systems are considered as promising tools in the fields of precise micro-machining and medicine applications. In the course of the development of reliable table top laser systems, a rapid growth of ultra-short pulse applications could be observed during the recent years. The key for improving the performance of high power laser systems is the quality of the optical components concerning spectral characteristics, optical losses and the power handling capability. In the field of ultra-short pulses, standard measurement procedures in quality management have to be validated in respect to effects induced by the extremely high peak power densities. The present work, which is embedded in the EUREKA-project CHOCLAB II, is predominantly concentrated on measuring the multiple-pulse LIDT (ISO 11254-2) in the fs-regime. A measurement facility based on a Ti:Sapphire-CPA system was developed to investigate the damage behavior of optical components. The set-up was supplied with an improved pulse energy detector discriminating the influence of pulse-to-pulse energy fluctuations on the incidence of damage. Aditionally, a laser-calorimetric measurement facility determining the absorption (ISO 11551) utilizing a fs-Ti:Sapphire laser was accomplished. The investigation for different pulse durations between 130 fs and 1 ps revealed a drastic increase of absorption in titania coatings for ultra-short pulses.

Critical behavior within 20 fs drives the out-of-equilibrium laser-induced magnetic phase transition in nickel.

Science.gov (United States)

Tengdin, Phoebe; You, Wenjing; Chen, Cong; Shi, Xun; Zusin, Dmitriy; Zhang, Yingchao; Gentry, Christian; Blonsky, Adam; Keller, Mark; Oppeneer, Peter M; Kapteyn, Henry C; Tao, Zhensheng; Murnane, Margaret M

2018-03-01

It has long been known that ferromagnets undergo a phase transition from ferromagnetic to paramagnetic at the Curie temperature, associated with critical phenomena such as a divergence in the heat capacity. A ferromagnet can also be transiently demagnetized by heating it with an ultrafast laser pulse. However, to date, the connection between out-of-equilibrium and equilibrium phase transitions, or how fast the out-of-equilibrium phase transitions can proceed, was not known. By combining time- and angle-resolved photoemission with time-resolved transverse magneto-optical Kerr spectroscopies, we show that the same critical behavior also governs the ultrafast magnetic phase transition in nickel. This is evidenced by several observations. First, we observe a divergence of the transient heat capacity of the electron spin system preceding material demagnetization. Second, when the electron temperature is transiently driven above the Curie temperature, we observe an extremely rapid change in the material response: The spin system absorbs sufficient energy within the first 20 fs to subsequently proceed through the phase transition, whereas demagnetization and the collapse of the exchange splitting occur on much longer, fluence-independent time scales of ~176 fs. Third, we find that the transient electron temperature alone dictates the magnetic response. Our results are important because they connect the out-of-equilibrium material behavior to the strongly coupled equilibrium behavior and uncover a new time scale in the process of ultrafast demagnetization.

Comparison of retina damage thresholds simulating the femtosecond-laser in situ keratomileusis (fs-LASIK) process with two laser systems in the CW- and fs-regime

Science.gov (United States)

Sander, M.; Minet, O.; Zabarylo, U.; Müller, M.; Tetz, M. R.

2012-04-01

The femtosecond-laser in situ keratomileusis procedure affords the opportunity to correct ametropia by cutting transparent corneal tissue with ultra-short laser pulses. Thereby the tissue cut is generated by a laser-induced optical breakdown in the cornea with ultra-short laser pulses in the near-infrared range. Compared to standard procedures such as photorefractive keratectomy and laser in-situ keratomileusis with the excimer laser, where the risk potential for the eye is low due to the complete absorption of ultraviolet irradiation from corneal tissue, only a certain amount of the pulse energy is deposited in the cornea during the fs-LASIK process. The remaining energy propagates through the eye and interacts with the retina and the strong absorbing tissue layers behind. The objective of the presented study was to determine and compare the retina damage thresholds during the fs-LASIK process simulated with two various laser systems in the CW- and fs-regime.

fs- and ns-laser processing of polydimethylsiloxane (PDMS) elastomer: Comparative study

Energy Technology Data Exchange (ETDEWEB)

Stankova, N.E., E-mail: nestankova@yahoo.com [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Atanasov, P.A.; Nedyalkov, N.N.; Stoyanchov, T.R. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Kolev, K.N.; Valova, E.I.; Georgieva, J.S.; Armyanov, St.A. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, S.; Wang, X.; Bruzzese, R. [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Grochowska, K.; Śliwiński, G. [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdańsk (Poland); Baert, K.; Hubin, A. [Vrije Universiteit Brussels, Faculty of Engineering, Research group, SURF “Electrochemical and Surface Engineering” (Belgium); Delplancke, M.P.; Dille, J. [Université Libre de Bruxelles, Materials Engineering, Characterization, Synthesis and Recycling (Service 4MAT), Faculté des Sciences Appliquées, 1050 Brussels (Belgium)

2015-05-01

Highlights: • fs- and ns-laser (266 and 532 nm) processing of PDMS-elastomer, in air, is studied. • High definition tracks (on the PDMS-elastomer surface) for electrodes are produced. • Selective Pt or Ni metallization of the tracks is produced via electroless plating. • Irradiated and metallized tracks are characterized by μ-Raman spectrometry and SEM. • DC resistance of Pt and Ni tracks is always between 0.5 and 15 Ω/mm. - Abstract: Medical grade polydimethylsiloxane (PDMS) elastomer is a widely used biomaterial as encapsulation and/or as substrate insulator carrier for long term neural implants because of its remarkable properties. Femtosecond (λ = 263 and 527 nm) and nanosecond (266 and 532 nm) laser processing of PDMS-elastomer surface, in air, is investigated. The influence of different processing parameters, including laser wavelength, pulse duration, fluence, scanning speed and overlapping of the subsequent pulses, on the surface activation and the surface morphology are studied. High definition tracks and electrodes are produced. Remarkable alterations of the chemical composition and structural morphology of the ablated traces are observed in comparison with the native material. Raman spectra illustrate well-defined dependence of the chemical composition on the laser fluence, pulse duration, number of pulses and wavelength. An extra peak about ∼512–518 cm{sup −1}, assigned to crystalline silicon, is observed after ns- or visible fs-laser processing of the surface. In all cases, the intensities of Si−O−Si symmetric stretching at 488 cm{sup −1}, Si−CH{sub 3} symmetric rocking at 685 cm{sup −1}, Si−C symmetric stretching at 709 cm{sup −1}, CH{sub 3} asymmetric rocking + Si−C asymmetric stretching at 787 cm{sup −1}, and CH{sub 3} symmetric rocking at 859 cm{sup −1}, modes strongly decrease. The laser processed areas are also analyzed by SEM and optical microscopy. Selective Pt or Ni metallization of the laser processed

In-pile test of Li{sub 2}TiO{sub 3} pebble bed with neutron pulse operation

Energy Technology Data Exchange (ETDEWEB)

Tsuchiya, K. E-mail: tsuchiya@oarai.jaeri.go.jp; Nakamichi, M.; Kikukawa, A.; Nagao, Y.; Enoeda, M.; Osaki, T.; Ioki, K.; Kawamura, H

2002-12-01

Lithium titanate (Li{sub 2}TiO{sub 3}) is one of the candidate materials as tritium breeder in the breeding blanket of fusion reactors, and it is necessary to show the tritium release behavior of Li{sub 2}TiO{sub 3} pebble beds. Therefore, a blanket in-pile mockup was developed and in situ tritium release experiments with the Li{sub 2}TiO{sub 3} pebble bed were carried out in the Japan Materials Testing Reactor. In this study, the relationship between tritium release behavior from Li{sub 2}TiO{sub 3} pebble beds and effects of various parameters were evaluated. The (R/G) ratio of tritium release (R) and tritium generation (G) was saturated when the temperature at the outside edge of the Li{sub 2}TiO{sub 3} pebble bed became 300 deg. C. The tritium release amount increased cycle by cycle and saturated after about 20 pulse operations.

Sub-40 fs, 1060-nm Yb-fiber laser enhances penetration depth in nonlinear optical microscopy of human skin

Science.gov (United States)

Balu, Mihaela; Saytashev, Ilyas; Hou, Jue; Dantus, Marcos; Tromberg, Bruce J.

2015-12-01

Advancing the practical utility of nonlinear optical microscopy requires continued improvement in imaging depth and contrast. We evaluated second-harmonic generation (SHG) and third-harmonic generation images from ex vivo human skin and showed that a sub-40 fs, 1060-nm Yb-fiber laser can enhance SHG penetration depth by up to 80% compared to a >100 fs, 800 nm Ti:sapphire source. These results demonstrate the potential of fiber-based laser systems to address a key performance limitation related to nonlinear optical microscopy (NLOM) technology while providing a low-barrier-to-access alternative to Ti:sapphire sources that could help accelerate the movement of NLOM into clinical practice.

Spectrally modified chirped pulse generation of sustained shock waves

International Nuclear Information System (INIS)

McGrane, S.D.; Moore, D.S.; Funk, D.J.; Rabie, R.L.

2002-01-01

A method is described for generating shock waves with 10-20 ps risetime followed by >200 ps constant pressure, using spectrally modified (clipped) chirped laser pulses. The degree of spectral clipping alters the chirped pulse temporal intensity profile and thereby the time-dependent pressure (tunable via pulse energy) generated in bare and nitrocellulose-coated Al thin films. The method is implementable in common chirped amplified lasers, and allows synchronous probing with a <200 fs pulse

Transport properties of Na doped La sub 1 sub - sub x Ca sub x sub - sub y Na sub y MnO sub 3 measured in a pulsed magnetic field

CERN Document Server

Bhattacharya, S; Pal, S; Chatterjee, P; Mukherjee, R K; Chaudhuri, B K

2002-01-01

Temperature-dependent magnetization and magnetoresistance of the Na doped La sub 1 sub - sub x Ca sub x sub sub - sub y Na sub y MnO sub 3 type samples with x=0.3 and 0 T sub p up to 320 K) conductivity data satisfy the variable range hopping (VRH) model. For T > 320 the small polaron hopping model is more appropriate than the VRH model. Even with a very small change of y, the density of states at the Fermi level N(E sub F) changes considerably. The resistivity of these materials measured under pulsed and continuous DC magnetic fields behaves in an identical fashion. The relaxation time (decay time of the magnetic pulse within the sample) varies with field strength, which indicates that, with a change of magnetic field, the ordering of spin in the ferromagnetic regime changes.

Short-pulse optical parametric chirped-pulse amplification for the generation of high-power few-cycle pulses

International Nuclear Information System (INIS)

Major, Zs.; Osterhoff, J.; Hoerlein, R.; Karsch, S.; Fuoloep, J.A.; Krausz, F.; Ludwig-Maximilians Universitaet, Muenchen

2006-01-01

Complete test of publication follows. In the quest for a way to generate ultrashort, high-power, few-cycle laser pulses the discovery of optical parametric amplification (OPA) has opened up to the path towards a completely new regime, well beyond that of conventional laser amplification technology. The main advantage of this parametric amplification process is that it allows for an extremely broad amplification bandwidth compared to any known laser amplifier medium. When combined with the chirped-pulse amplification (CPA) principle (i.e. OPCPA), on one hand pulses of just 10 fs duration and 8 mJ pulse energy have been demonstrated. On the other hand, pulse energies of up to 30 J were also achieved on a different OPCPA system; the pulse duration in this case, however, was 100 fs. In order to combine ultrashort pulse durations (i.e. pulses in the few-cycle regime) with high pulse energies (i.e. in the Joule range) we propose tu pump on OPCPA chain with TW-scale short pulses (100 fs - 1 ps instead of > 100 ps of previous OPCPA systems) delivered by a conventional CPA system. This approach inherently improves the conditions for generating high-power ultrashort pulses using OPCPA in the following ways. Firstly, the short pump pulse duration reduces the necessary stretching factor for the seed pulse, thereby increasing stretching and compression fidelity. Secondly, also due to the shortened pump pulse duration, a much higher contrast is achieved. Finally, the significantly increased pump power makes the use of thinner OPCPA crystals possible, which implies an even broader amplification bandwidth, thereby allowing for even shorter pulses. We carried out theoretical investigations to show the feasibility of such a set-up. Alongside these studies we will also present preliminary experimental results of an OPCPA system pumped by the output of our Ti:Sapphire ATLAS laser, currently delivering 350 mJ in 43 fs. An insight into the planned scaling of this technique to petawatt

Current-induced domain wall motion in Ni{sub 80}Fe{sub 20} nanowires with low depinning fields

Energy Technology Data Exchange (ETDEWEB)

Malinowski, Gregory; Loerincz, Andreas; Krzyk, Stephen; Moehrke, Philipp; Bedau, Daniel; Boulle, Olivier; Rhensius, Jan; Klaeui, Mathias [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, D-78457 (Germany); Heyderman, Laura J [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Cho, Young Jin; Seo, Sunae, E-mail: gregory.malinowski@uni-konstanz.d [Samsung Electronics, San 14-1 Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do (Korea, Republic of)

2010-02-03

In this paper, we report on domain wall (DW) motion induced by current pulses at variable temperature in 900 nm wide and 25 nm thick Ni{sub 80}Fe{sub 20} wires with low pinning fields. By using Ar ion milling to pattern our wires rather than the conventional lift-off technique, a depinning field as low as {approx}2-3 Oe at room temperature is obtained. Comparison with previous results acquired on similar wires with much higher pinning shows that the critical current density scales with the depinning field, leading to a critical current density of {approx}2.5 x 10{sup 11} A m{sup -2} at 250 K. Moreover, when a current pulse with a current density larger than the critical current density is injected, the DW is not necessarily depinned but it can undergo a modification of its spin structure which hinders current-induced DW motion. Hence, reliable propagation of the DW requires an accurate adjustment of the pulsed current density.

Propagation of 1-THz bandwidth electrical pulses on high Tc superconducting transmission lines

International Nuclear Information System (INIS)

Nuss, M.C.; Mankiewich, P.M.; Howard, R.E.; Harvey, T.E.; Brandle, C.D.; Straugh, B.L.; Smith, P.R.

1989-01-01

The new high temperature superconductors have triggered enormous interest not only because of the unique physics involved but also because of their technical potentials, such as the promise for propagation of extremely short electrical pulses. Superconducting band caps of --20TH z are predicted assuming BCS theory for the superconductor, making lossless propagation of electrical pulses as short as 50 fs possible. Despite microwave measurements at low frequencies of several gigahertz first studies at higher frequencies by Dykaar et al have shown distortion-free propagation of 100-GHz electrical pulses on YBa 2 Cu 3 O 3 (YBCO) lines for --5-mm propagation distance. Results were also reported for aluminum coplanar lines and a YBCO ground plane. The authors report on the propagation of 1-ps electrical pulses (1-THz bandwidth) on YBCO coplanar transmission lines defined on lanthanum gallate (LaGaO 3 ) as a substrate. On LaGaO 3 , YBCO grows highly oriented as on SrTiO 3 . However, unlike SrTiO 3 , LaGaO 3 has a much lower dielectric constant and small losses in the terahertz frequency range. Electrical pulses of --750-fs duration are generated in a radiation-damaged silicon-on-sapphire photoconductive switch integrated into a 20-μm coplanar stripline with 10-μm spacing and excited with 100-fs optical pulses from a CPM laser. An μ1-THz bandwidth electrical contact is made to the YBCO coplanar stripline defined on LaGaO 3 using a flip-chip geometry. They find that electrical pulses broaden only from 750 fs to 1 ps with little loss in amplitude on traveling through their flip-chip input and propagated electrical pulses are probed by electooptic sampling in two small LiTaO 3 crystals separated by 3 mm

Gigahertz repetition rate, sub-femtosecond timing jitter optical pulse train directly generated from a mode-locked Yb:KYW laser.

Science.gov (United States)

Yang, Heewon; Kim, Hyoji; Shin, Junho; Kim, Chur; Choi, Sun Young; Kim, Guang-Hoon; Rotermund, Fabian; Kim, Jungwon

2014-01-01

We show that a 1.13 GHz repetition rate optical pulse train with 0.70 fs high-frequency timing jitter (integration bandwidth of 17.5 kHz-10 MHz, where the measurement instrument-limited noise floor contributes 0.41 fs in 10 MHz bandwidth) can be directly generated from a free-running, single-mode diode-pumped Yb:KYW laser mode-locked by single-wall carbon nanotube-coated mirrors. To our knowledge, this is the lowest-timing-jitter optical pulse train with gigahertz repetition rate ever measured. If this pulse train is used for direct sampling of 565 MHz signals (Nyquist frequency of the pulse train), the jitter level demonstrated would correspond to the projected effective-number-of-bit of 17.8, which is much higher than the thermal noise limit of 50 Ω load resistance (~14 bits).

Laser modification of silica, simulating pulse shape and length

International Nuclear Information System (INIS)

Corrales, L. Rene; Moore, Emily

2009-01-01

Computer simulations of instantaneous thermal heating due to a laser pulse is modeled as a pulse occurring over 1 or 100 fs, during which time the atoms within a cylinder are given excess kinetic energy to mimic the effect of adding energy locally to a system by a laser. The response of the material under conditions in which a similar amount of energy is dumped within 1 fs versus over a 100 fs pulse with two distinct shapes, square and Gaussian-like, is explored. Key physics disclosed is that with a pulse width of 100 fs, as the energy is being added it begins to dissipate away from region where it is added. With a 1 fs (instantaneous) pulse there is greater initial ballistic behavior than when it is dumped over a 100 fs period. In the latter, there are localized hot spots displaying ballistic behavior.

Erbium:ytterbium fiber-laser system delivering watt-level femtosecond pulses using divided pulse amplification

Science.gov (United States)

Herda, Robert; Zach, Armin

2015-03-01

We present an Erbium:Ytterbium codoped fiber-amplifer system based on Divided-Pulses-Amplification (DPA) for ultrashort pulses. The output from a saturable-absorber mode-locked polarization-maintaining (PM) fiber oscillator is amplified in a PM normal-dispersion Erbium-doped fiber. After this stage the pulses are positively chirped and have a duration of 2.0 ps at an average power of 93 mW. A stack of 5 birefringent Yttrium-Vanadate crystals divides these pulses 32 times. We amplify these pulses using a double-clad Erbium:Ytterbium codoped fiber pumped through a multimode fiber combiner. The pulses double pass the amplifier and recombine in the crystals using non-reciprocal polarization 90° rotation by a Faraday rotating mirror. Pulses with a duration of 144 fs are obtained after separation from the input beam using a polarizing beam splitter cube. These pulses have an average power of 1.85 W at a repetition rate of 80 MHz. The generation of femtosecond pulses directly from the amplifier was enabled by a positively chirped seed pulse, normally dispersive Yttrium-Vanadate crystals, and anomalously dispersive amplifier fibers. Efficient frequency doubling to 780 nm with an average power of 725 mW and a pulse duration of 156 fs is demonstrated. In summary we show a DPA setup that enables the generation of femtosecond pulses at watt-level at 1560 nm without the need for further external dechirping and demonstrate a good pulse quality by efficient frequency doubling. Due to the use of PM fiber components and a Faraday rotator the setup is environmentally stable.

LIAD-fs: A novel method for studies of ultrafast processes in gas phase neutral biomolecules

International Nuclear Information System (INIS)

Calvert, C R; Kelly, O; Duffy, M J; Belshaw, L; King, R B; Williams, I D; Greenwood, J B

2012-01-01

A new experimental technique for femtosecond (fs) pulse studies of gas phase biomolecules is reported. Using Laser-Induced Acoustic Desorption (LIAD) to produce a plume of neutral molecules, a time-delayed fs pulse is employed for ionisation/fragmentation, with subsequent products extracted and mass analysed electrostatically. By varying critical laser pulse parameters, this technique can be used to implement control over molecular fragmentation for a range of small biomolecules, with specific studies of amino acids demonstrated.

Growth of centimeter-scale atomically thin MoS{sub 2} films by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Siegel, Gene; Venkata Subbaiah, Y. P.; Prestgard, Megan C.; Tiwari, Ashutosh, E-mail: tiwari@eng.utah.edu [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

2015-05-01

We are reporting the growth of single layer and few-layer MoS{sub 2} films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS{sub 2} target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 °C in an ambient vacuum of 10{sup −6} Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM), Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL) measurements. The ablation of the MoS{sub 2} target by 50 laser pulses (energy density: 1.5 J/cm{sup 2}) was found to result in the formation of a monolayer of MoS{sub 2} as shown by AFM results. In the Raman spectrum, A{sub 1g} and E{sup 1}{sub 2g} peaks were observed at 404.6 cm{sup −1} and 384.5 cm{sup −1} with a spacing of 20.1 cm{sup −1}, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV) and 615 nm (2.02 eV), with an energy split of 0.17 eV, which is in excellent agreement with the theoretically predicted value of 0.15 eV. The monolayer MoS{sub 2} exhibited a PL peak at 1.85 eV confirming the direct nature of the band-gap. By varying the number of laser pulses, bi-layer, tri-layer, and few-layer MoS{sub 2} films were prepared. It was found that as the number of monolayers (n) in the MoS{sub 2} films increases, the spacing between the A{sub 1g} and E{sup 1}{sub 2g} Raman peaks (Δf) increases following an empirical relation, Δf=26.45−(15.42)/(1+1.44 n{sup 0.9}) cm{sup −1}.

High-power pre-chirp managed amplification of femtosecond pulses at high repetition rates

International Nuclear Information System (INIS)

Liu, Yang; Li, Wenxue; Zhao, Jian; Bai, Dongbi; Luo, Daping; Zeng, Heping

2015-01-01

Femtosecond pulses at 250 MHz repetition rate from a mode-locked fiber laser are amplified to high power in a pre-chirp managed amplifier. The experimental strategy offers a potential towards high-power ultrashort laser pulses at high repetition rates. By investigating the laser pulse evolution in the amplification processes, we show that self-similar evolution, finite gain bandwidth and mode instabilities determine pulse characteristics in different regimes. Further average power scaling is limited by the mode instabilities. Nevertheless, this laser system enables us to achieve sub-50 fs pulses with an average power of 93 W. (letter)

Study and realisation of a femtosecond dye laser operating at different wavelengths. Ultrashort pulses compression and amplification

International Nuclear Information System (INIS)

Georges, Patrick

1989-01-01

We present the study and the realization of a passively mode-locked dye laser producing pulses shorter than 100 femto-seconds (10 -13 s). In a ring cavity with an amplifier medium (Rhodamine 60) and a saturable absorber (DODCI), a sequence of four prisms controls the group velocity dispersion and allows the generation of very short pulses. Then we have studied the production of femtosecond pulses at other wavelengths directly from the femtosecond dye laser. For the first rime, 60 fs pulses at 685 nm and pulses shorter than 50 fs between 775 nm and 800 nm have been produced by passive mode locking. These near infrared pulses have been used to study the absorption saturation kinetics in semiconductors multiple quantum wells GaAs/GaAlAs. We have observed a singular behavior of the laser operating at 685 nm and analyzed the produced pulses in terms of optical solitons. To perform time resolved spectroscopy with shortest pulses, we have studied a pulse compressor and a multipass amplifier to increase the pulses energy. Pulses of 20 fs and 10 micro-joules (peak power: 0.5 GW) have been obtained at low repetition rate (10 Hz) and pulses of 16 fs and 0.6 micro-joules pulses have been generated at high repetition rate (11 kHz) using a copper vapor laser. These pulses have been used to study the absorption saturation kinetics of an organic dye (the Malachite Green). (author) [fr

Measurement of x-ray emission and thermal transport in near-solid-density plasmas heated by 130 fs laser pulses

International Nuclear Information System (INIS)

Young, B.K.; Wilson, B.G.; Price, D.F.; Stewart, R.E.

1998-01-01

Near-solid-density plasmas with peak temperatures of 370±50 eV have been generated using a high-contrast (∼10 -7 ), 400 nm, 130 fs laser pulse of intensity 3x10 17 Wcm -2 at the Ultrashort Pulse Laser at Lawrence Livermore National Laboratory. The x-ray-emission spectra from thin tracer layers of germanium, tamped by layers of plastic, were measured as a function of target depth. The results qualitatively agree with calculations based on detailed local thermodynamic equilibrium (LTE) and modified non-LTE spectroscopic opacity models using plasma conditions determined using LASNEX hydrodynamic simulations. No evidence of thermal flux inhibition into the bulk target material was observed. The experiments and detailed simulations are presented. copyright 1998 The American Physical Society

Laser assisted removal of synthetic painting-conservation materials using UV radiation of ns and fs pulse duration: Morphological studies on model samples

International Nuclear Information System (INIS)

Pouli, P.; Nevin, A.; Andreotti, A.; Colombini, P.; Georgiou, S.; Fotakis, C.

2009-01-01

In an effort to establish the optimal parameters for the cleaning of complex layers of polymers (mainly based on acrylics, vinyls, epoxys known as Elvacite, Laropal, Paraloid B72, among others) applied during past conservation treatments on the surface of wall paintings, laser cleaning tests were performed with particular emphasis on the plausible morphological modifications induced in the remaining polymeric material. Pulse duration effects were studied using laser systems of different pulse durations (ns and fs) at 248 nm. Prior to tests on real fragments from the Monumental Cemetery in Pisa (Italy) which were coated with different polymers, attention was focused on the study of model samples consisting of analogous polymer films cast on quartz disks. Ultraviolet irradiation is strongly absorbed by the studied materials both in ns and fs irradiation regimes. However, it is demonstrated that ultrashort laser pulses result in reduced morphological alterations in comparison to ns irradiation. In addition, the dependence of the observed alterations on the chemical composition of the consolidation materials in both regimes was examined. Most importantly, it was shown that in this specific conservation problem, an optimum cleaning process may rely not only on the minimization of laser-induced morphological changes but also on the exploitation of the conditions that favour the disruption of the adhesion between the synthetic material and the painting.

Mechanism for negative corona current pulse in CO sub 2 -SF sub 6 mixtures

CERN Document Server

Zahoranova, A; Simor, M; Cernak, M

2003-01-01

Current waveforms of first negative corona pulses have been measured in CO sub 2 -SF sub 6 mixtures over a pressure range extending from 6.65 to 50 kPa and various overvoltages. Effects of changing cathode secondary electron emission were studied using a copper cathode coated by CuI and graphite. For a given set of experimental conditions it is concluded that in the mixtures containing up to 30% of SF sub 6 the negative corona pulse is associated with the formation of a cathode-directed streamer-like ionizing wave in the immediate vicinity of the cathode. This is in contrast to the discharge behaviour in air-SF sub 6 and N sub 2 -SF sub 6 mixtures, where in similar conditions the discharge develops according to a multi-avalanche Townsend mechanism. (rapid communication)

Pulsed laser deposition of AlMgB<sub>14sub> thin films

Energy Technology Data Exchange (ETDEWEB)

Britson, Jason Curtis [Iowa State Univ., Ames, IA (United States)

2008-11-18

Hard, wear-resistant coatings of thin film borides based on AlMgB<sub>14sub> have the potential to be applied industrially to improve the tool life of cutting tools and pump vanes and may account for several million dollars in savings as a result of reduced wear on these parts. Past work with this material has shown that it can have a hardness of up to 45GPa and be fabricated into thin films with a similar hardness using pulsed laser deposition. These films have already been shown to be promising for industrial applications. Cutting tools coated with AlMgB<sub>14sub> used to mill titanium alloys have been shown to substantially reduce the wear on the cutting tool and extend its cutting life. However, little research into the thin film fabrication process using pulsed laser deposition to make AlMgB<sub>14sub> has been conducted. In this work, research was conducted into methods to optimize the deposition parameters for the AlMgB<sub>14sub> films. Processing methods to eliminate large particles on the surface of the AlMgB<sub>14sub> films, produce films that were at least 1m thick, reduce the surface roughness of the films, and improve the adhesion of the thin films were investigated. Use of a femtosecond laser source rather than a nanosecond laser source was found to be effective in eliminating large particles considered detrimental to wear reduction properties from the films. Films produced with the femtosecond laser were also found to be deposited at a rate 100 times faster than those produced with the nanosecond laser. However, films produced with the femtosecond laser developed a relatively high RMS surface roughness around 55nm. Attempts to decrease the surface roughness were largely unsuccessful. Neither increasing the surface temperature of the substrate during deposition nor using a double pulse to ablate the material was found to be extremely successful to reduce the surface roughness. Finally, the adhesion of the thin films to M2 tool steel

CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

Science.gov (United States)

Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

2010-02-01

An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

High efficiency, monolithic fiber chirped pulse amplification system for high energy femtosecond pulse generation.

Science.gov (United States)

Peng, Xiang; Kim, Kyungbum; Mielke, Michael; Jennings, Stephen; Masor, Gordon; Stohl, Dave; Chavez-Pirson, Arturo; Nguyen, Dan T; Rhonehouse, Dan; Zong, Jie; Churin, Dmitriy; Peyghambarian, N

2013-10-21

A novel monolithic fiber-optic chirped pulse amplification (CPA) system for high energy, femtosecond pulse generation is proposed and experimentally demonstrated. By employing a high gain amplifier comprising merely 20 cm of high efficiency media (HEM) gain fiber, an optimal balance of output pulse energy, optical efficiency, and B-integral is achieved. The HEM amplifier is fabricated from erbium-doped phosphate glass fiber and yields gain of 1.443 dB/cm with slope efficiency >45%. We experimentally demonstrate near diffraction-limited beam quality and near transform-limited femtosecond pulse quality at 1.55 µm wavelength. With pulse energy >100 µJ and pulse duration of 636 fs (FWHM), the peak power is estimated to be ~160 MW. NAVAIR Public Release Distribution Statement A-"Approved for Public release; distribution is unlimited".

Fiber Coupled Pulse Shaper for Sub-Nanosecond Pulse Lidar, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — This Small Business Innovation Research Phase II effort will develop an all-diode laser and fiber optic based, single frequency, sub-nanosecond pulsed laser source...

SeaWiFS: North Pacific Storm

Science.gov (United States)

2002-01-01

An extratropical storm can be seen swirling over the North Pacific just south of Alaska. This SeaWiFS image was collected yesterday at 23:20 GMT. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

Indium-modified Yb:KLu(WO{sub 4}){sub 2} crystal: Growth, spectroscopy and laser operation

Energy Technology Data Exchange (ETDEWEB)

Serres, J.M. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona E-43007 (Spain); Mateos, X., E-mail: xavier.mateos@urv.cat [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona E-43007 (Spain); Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., Berlin D-12489 (Germany); Loiko, P. [ITMO University, 49 Kronverkskiy pr., St. Petersburg 197101 (Russian Federation); Griebner, U.; Petrov, V. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., Berlin D-12489 (Germany); Yumashev, K. [Center for Optical Materials and Technologies (COMT), Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Aguiló, M.; Díaz, F. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona E-43007 (Spain)

2017-03-15

We report on the growth, spectroscopic and laser characterization of a novel monoclinic laser crystal, Yb,In:KLu(WO{sub 4}){sub 2} (Yb,In:KLuW). The absorption, stimulated-emission and gain cross-section spectra of 3.5 at% Yb, 5.5 at% In-doped KLuW are determined at room temperature with polarized light and compared with those for Yb,In:KYW, as well as singly Yb-doped KLuW and KYW crystals. It is found that the introduction of In results in a decrease of the transition cross-sections and in a spectral broadening of the absorption and emission bands. Such a broadening is more pronounced for light polarization E ||N{sub p}. For Yb,In:KLuW, the maximum σ{sub abs} is 9.9×10{sup –20} cm{sup 2} at 980.9 nm for E ||N{sub m} and the corresponding bandwidth of the absorption peak is 3.7 nm. The radiative lifetime for Yb{sup 3+} ions is 237±5 µs. The stimulated-emission cross-sections are σ{sub SE}(m)=2.4×10{sup –20} cm{sup 2} at 1022.4 nm and σ{sub SE}(p)=1.3×10{sup –20} cm{sup 2} at 1039.1 nm corresponding to an emission bandwidth of >30 nm and >35 nm, respectively. The diode-pumped N{sub g}-cut Yb,In:KLuW microchip laser generated 4.11 W at 1042–1048 nm with a slope efficiency of 78%. The Yb,In:KLuW crystal is very promising for the generation of sub-100 fs pulses in mode-locked lasers due to its broadband emission characteristics.

Coatings synthesised by the pulsed laser ablation of a B{sub 4}C/W{sub 2}B{sub 5} ceramic composite

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar, Fann Dakar (Senegal); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050 Johannesburg (South Africa); Nuru, Z.Y.; Kotsedi, L.; Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Van Zyl, R.R. [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa)

2015-10-30

A pellet of B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was characterised and subjected to pulsed laser ablation for the deposition of coatings on corning glass substrates. We reports an attempt to produce coatings from B{sub 4}C/W{sub 2}B{sub 5} by pulsed laser deposition (PLD). The thermal, electric and mechanical properties of B{sub 4}C/W{sub 2}B{sub 5} suggest that coatings synthesised from this composite can be used for space applications. The samples were characterised using X-ray Diffraction, Atomic Force Microscopy and Heavy Ion Elastic Recoil Detection Analysis. The characterisation of the samples deposited on soda lime corning glass showed that the laser energy used in this PLD was enough to obtain non amorphous coatings formed by some alteration of the tungsten carbide crystal lattice at room temperature, and that there was no stoichiometry transfer as would be expected from PLD. The coating also showed space applicable features worth investigating. - Highlights: • B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was ablated for deposition on corning glass subtrates. • Non-amorphous coating was obtained at room temperature. • There was no stoichiometry transfer as would be expected from Pulsed Laser Deposition.

Pulsed irradiation of enriched UO{sub 2} in the Annular Core Pulse Reactor (ACPR)

Energy Technology Data Exchange (ETDEWEB)

Schmidt, T R; Lucoff, D M; Reil, K O; Croucher, D W [Sandia Laboratories (United States)

1974-07-01

A series of experiments have been conducted in the Annular Core Pulse Reactor (ACPR) to determine the energy deposition and behavior of enriched UO{sub 2} under pulse conditions. In the experiment single unirradiated pellets with enrichments up to 25 percent were pulse heated to melt temperatures. Temperature and fission product inventory measurements were made and compared with neutron transport calculations. (author)

Nearly fully compressed 1053 nm pulses directly obtained from 800 nm laser-seeded photonic crystal fiber below zero dispersion point

Science.gov (United States)

Refaeli, Zaharit; Shamir, Yariv; Ofir, Atara; Marcus, Gilad

2018-02-01

We report a simple robust and broadly spectral-adjustable source generating near fully compressed 1053 nm 62 fs pulses directly out of a highly-nonlinear photonic crystal fiber. A dispersion-nonlinearity balance of 800 nm Ti:Sa 20 fs pulses was obtained initially by negative pre-chirping and then launching the pulses into the fibers' normal dispersion regime. Following a self-phase modulation spectral broadening, some energy that leaked below the zero dispersion point formed a soliton whose central wavelength could be tuned by Self-Frequency-Raman-Shift effect. Contrary to a common approach of power, or, fiber-length control over the shift, here we continuously varied the state of polarization, exploiting the Raman and Kerr nonlinearities responsivity for state of polarization. We obtained soliton pulses with central wavelength tuned over 150 nm, spanning from well below 1000 to over 1150 nm, of which we could select stable pulses around the 1 μm vicinity. With linewidth of > 20 nm FWHM Gaussian-like temporal-shape pulses with 62 fs duration and near flat phase structure we confirmed high quality pulse source. We believe such scheme can be used for high energy or high power glass lasers systems, such as Nd or Yb ion-doped amplifiers and systems.

Ultrafast control and monitoring of material properties using terahertz pulses

Energy Technology Data Exchange (ETDEWEB)

Bowlan, Pamela Renee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Lab. for Ultrafast Materials Optical Science (LUMOS)

2016-05-02

These are a set of slides on ultrafast control and monitoring of material properties using terahertz pulses. A few of the topics covered in these slides are: How fast is a femtosecond (fs), Different frequencies probe different properties of molecules or solids, What can a THz pulse do to a material, Ultrafast spectroscopy, Generating and measuring ultrashort THz pulses, Tracking ultrafast spin dynamics in antiferromagnets through spin wave resonances, Coherent two-dimensional THz spectroscopy, and Probing vibrational dynamics at a surface. Conclusions are: Coherent two-dimensional THz spectroscopy: a powerful approach for studying coherence and dynamics of low energy resonances. Applying this to graphene we investigated the very strong THz light mater interaction which dominates over scattering. Useful for studying coupled excitations in multiferroics and monitoring chemical reactions. Also, THz-pump, SHG-probe spectoscopy: an ultrafast, surface sensitive probe of atomic-scale symmetry changes and nonlinear phonon dymanics. We are using this in Bi<sub>2sub>Se>3sub> to investigate the nonlinear surface phonon dynamics. This is potentially very useful for studying catalysis.

Analysis on characteristic and application of THz frequency comb and THz sub-comb

International Nuclear Information System (INIS)

Liu Pengxiang; Xu Degang; Yao Jianquan

2011-01-01

In this paper, we proposed a method for THz sub-comb generation based on spectral interference. The result of our calculation indicated that the THz pulse train, generated by surface-emitted optical rectification of femtosecond (fs) laser pulse in periodically poled lithium niobate (PPLN), has a comb-like spectrum. The characteristic of this THz sub-comb was analyzed both in frequency and time domain. Compared with the THz frequency comb emitted by a photoconductive antenna (PCA), THz sub-comb has a lower spectral resolution and wider free spectral range. Thus it could be an ideal source for wavelength division multiplexing (WDM) in THz wireless communication system.

Hybrid fs/ps CARS for Sooting and Particle-laden Flames

Energy Technology Data Exchange (ETDEWEB)

Hoffmeister, Kathryn N. Gabet; Guildenbecher, Daniel Robert; Kearney, Sean P.

2015-12-01

We report the application of ultrafast rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning aluminized ammonium perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laserbased diagnostics, with intense background luminosity, scattering and beam obstruction from hot metal particles that can be as large as several hundred microns in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminumparticle- seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulateenhanced laser-induced breakdown. Introduction of fs/ps laser pulses enables CARS detection at reduced pulse energies, decreasing the likelihood of breakdown, while simultaneously providing time-gated elimination of any nonresonant background interference. Temperature probability densities and temperature/oxygen correlations were constructed from ensembles of several thousand single-laser-shot measurements from the fs/ps rotational CARS measurement volume positioned within 3 mm or less of the burning propellant surface. Preliminary results in canonical flames are presented using a hybrid fs/ps vibrational CARS system to demonstrate our progress towards acquiring vibrational CARS measurements for more accurate temperatures in the very high temperature propellant burns.

An Advantage of the Equivalent Velocity Spectroscopy for Femtsecond Pulse Radiolysis

CERN Document Server

Kondoh, Takafumi; Tagawa, Seiichi; Tomosada, Hiroshi; Yang Jin Feng; Yoshida, Yoichi

2005-01-01

For studies of electron beam induced ultra-fast reaction process, femtosecond(fs) pulse radiolysis is under construction. To realize fs time resolution, fs electron and analyzing light pulses and their jitter compensation system are needed. About a 100fs electron pulse was generated by a photocathode RF gun linac and a magnetic pulse compressor. Synchronized Ti: Sapphire laser have a puleswidth about 160fs. And, it is significant to avoid degradation of time resolution caused by velocity difference between electron and analyzing light in a sample. In the 'Equivalent velocity spectroscopy' method, incident analyzing light is slant toward electron beam with an angle associated with refractive index of sample. Then, to overlap light wave front and electron pulse shape, electron pulse shape is slanted toward the direction of travel. As a result of the equivalent velocity spectroscopy for hydrated electrons, using slanted electron pulse shape, optical absorption rise time was about 1.4ps faster than normal electro...

Cubic phase control of ultrashort laser pulses

International Nuclear Information System (INIS)

Mecseki, K.; Erdelyi, M.; Kovacs, A.P.; Szabo, G.

2006-01-01

the 40 μrad/nm value. For experimental verification, the cubic compressor was placed in one arm of a Michelson-type interferometer illuminated by a Ti:sapphire oscillator providing 20 fs (FWHM) pulses at a central wavelength of 800 nm. The compressor consisted of a calcite crystal with a radius of 15 nm and an achromatic lens with a magnification of 4 in accordance with the simulation results. The dispersion coefficients of the compressor were determined from the spectrally resolved interferograms (SRI). During the experiments, special attention was paid to minimizing the angular dispersion of the pulse leaving the compressor. The measured GDD and TOD were 3.8 x 10 3 fs 2 and -2.6 x 10 5 fs 3 , while the calculated values were 3.2 x 10 3 fs 2 and -1.9 x 10 5 fs 3 , respectively. Taking into consideration the paraxial approximation based simulation, the 25% average error of the dispersion values is acceptable. The simulation results can be used as rough estimation, and SRI can be applied for real-time fine tuning.

Photocatalytic activity of bipolar pulsed magnetron sputter deposited TiO{sub 2}/TiWO{sub x} thin films

Energy Technology Data Exchange (ETDEWEB)

Weng, Ko-Wei; Hu, Chung-Hsuan; Hua, Li-Yu; Lee, Chin-Tan [Department of Electronic Engineering, National Quemoy University, 1 Daxue Road, Jinning Township, Kinmen 89250, Taiwan, ROC (China); Zhao, Yu-Xiang [Department of Computer Science and Information Engineering, National Quemoy University, Taiwan, ROC (China); Chang, Julian; Yang, Shu-Yi [Department of Applied English, National Quemoy University, Taiwan, ROC (China); Han, Sheng, E-mail: shenghan@nutc.edu.tw [Center for General Education, National Taichung University of Science and Technology, 129 San-min Road, Section 3, Taichung 40401, Taiwan, ROC (China)

2016-08-15

Highlights: • TiO{sub 2}/TiWO{sub x} films were fabricated by a bipolar pulsed magnetron sputtering apparatus. • Titanium oxide being sputtered tungsten enhanced the highly oriented of TiO{sub 2} (1 0 1) plane of the specimen assemblies. • The mechanism WO{sub 3}(h{sup +}, e{sup −})/TiO{sub 2}(h{sup +}, e{sup −}) → WO{sub 3}(e{sup −})/TiO{sub 2}(h{sup +}) shows the higher hydrophilicity and lower contact angle. - Abstract: Titanium oxide films were formed by sputtering and then TiWO{sub x} films were deposited by bipolar pulsed magnetron sputtering with pure titanium and tungsten metal targets. The sputtering of titanium oxide with tungsten enhanced the orientation of the TiO{sub 2} (1 0 1) plane of the specimen assemblies. The main varying parameter was the tungsten pulse power. Titanium oxide sputtered with tungsten using a pulsing power of 50 W exhibited a superior hydrophilic property, and a contact angle of 13.1°. This fabrication conditions maximized the photocatalytic decomposition of methylene blue solution. The mechanism by which the titanium oxide was sputtered with tungsten involves the photogeneration of holes and electron traps, inhibiting the hole–electron recombination, enhancing hydrophilicity and reducing the contact angle.

Analysis of gases by a pulsed voltammetric sensor and the electrochemistry of high T[sub c] superconductors

Energy Technology Data Exchange (ETDEWEB)

Rochani, S.

1991-01-01

This thesis is presented in two parts: Studies of gas sensing probes and the electrochemistry of superconductors. A Clark type polarographic oxygen sensor was used to analyze oxygen, hydrogen, chlorine, sulphur dioxide and nitrogen dioxide. A pulsed potential was applied driven by an IBM/XT compatible microcomputer with a 12 bit A-D/D-A card. In a series of experiments for each gas singly, and then mixtures, the probe was calibrated at different concentrations of gas dissolved in water at different times during the pulse to observe the optimum measurement. In the case of oxygen for a 20 s pulse at [minus]0.65 V between a platinum and silver/silver chloride, the optimum calibration was obtained between 2 and 4 s with a detection limit of 0.27 ppm oxygen. Hydrogen was determined at +0.60 V with a 50 s pulse and optimum range 3 to 4 s and detection limit 0.02 ppm. Chlorine was reduced at 0 V and optimally detected after 2 s of a 20 s pulse with a detection limit of 3 ppm. A mixture of hydrogen and oxygen was analyzed without mutual interference by a train of pulses at [minus]0.65, 0, +0.60 V or [minus]0.65, +0.60 V. For sulphur dioxide, a new probe was constructed with a separate reference, working and auxillary electrodes to overcome the formation of silver sulphide at the auxillary electrode. A preliminary study of nitrogen dioxide was done by observing the oxidation and reduction current at different applied voltages. Samples of each of the room temperature superconductors YBa[sub 2]Cu[sub 3]O[sub 7[minus][sigma

Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses

International Nuclear Information System (INIS)

Bionta, M. R.; Hartmann, N.; Weaver, M.; French, D.; Glownia, J. M.; Bostedt, C.; Chollet, M.; Ding, Y.; Fritz, D. M.; Fry, A. R.; Krzywinski, J.; Lemke, H. T.; Messerschmidt, M.; Schorb, S.; Zhu, D.; White, W. E.; Nicholson, D. J.; Cryan, J. P.; Baker, K.; Kane, D. J.

2014-01-01

The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10–100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for “measure-and-sort” at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses

Three-dimensional laser pulse intensity diagnostic for photoinjectors

Directory of Open Access Journals (Sweden)

Heng Li

2011-11-01

Full Text Available Minimizing the electron-beam emittance of photoinjectors is an important task for maximizing the brightness of the next-generation x-ray facilities, such as free-electron lasers and energy recovery linacs. Optimally shaped laser pulses can significantly reduce emittance. A reliable diagnostic for the laser pulse intensity is required for this purpose. We demonstrate measurement of three-dimensional spatiotemporal intensity profiles, with spatial resolution of 20  μm and temporal resolution of 130 fs. The capability is illustrated by measurements of stacked soliton pulses and pulses from a dissipative-soliton laser.

High-order harmonic generation spectra and isolated attosecond pulse generation with a two-color time delayed pulse

International Nuclear Information System (INIS)

Feng Liqiang; Chu Tianshu

2012-01-01

Highlights: ► Investigation of HHG spectra and single isolated attosecond pulse generation. ► Irradiation from a model Ne atom by two-color time delayed pulse. ► Observation of time delay effect and relative phase effect. ► Revelation of the optimal condition for generating isolated attosecond pulse. ► Generation of a single isolated attosecond pulse of 45as. - Abstract: In this paper, we theoretically investigate the delay time effect on the high-order harmonic generation (HHG) when a model Ne atom is exposed to a two-color time delayed pulse, consisting of a 5fs/800 nm fundamental field and a 20fs/2000 nm controlling field. It shows that the HHG spectra are strongly sensitive to the delay time between the two laser fields, in particular, for the zero carrier-envelope phase (CEP) φ case (corresponding to the 800 nm fundamental field), the maximum cutoff energy has been achieved at zero delay time. However, with the introduction of the CEP (φ = 180°), the delay effect on HHG is changed, exhibiting a ‘U’ structure harmonic emission from −1 T to 1 T. In addition, the combinations of different controlling pulse frequencies and pulse intensities have also been considered, showing the similar results as the original controlling field case, but with some characteristics. Finally, by properly superposing the optimal harmonic spectrum, an isolated 45as pulse is generated without phase compensation.

Ultrafast, ultrahigh-peak power Ti:sapphire laser system

Energy Technology Data Exchange (ETDEWEB)

Yamakawa, Koichi; Aoyama, Makoto; Matsuoka, Shinichi; Akahane, Yutaka; Kase, Teiji; Nakano, Fumihiko; Sagisaka, Akito [Advanced Photon Research Center, Kansai Research Establishment, Japan Atomic Energy Research Inst., Kizu, Kyoto (Japan)

2001-01-01

We review progress in the generation of multiterawatt optical pulses in the 10-fs range. We describe a design, performance and characterization of a Ti:sapphire laser system based on chirped-pulse amplification, which has produced a peak power in excess of 100-TW with sub-20-fs pulse durations and an average power of 19-W at a 10-Hz repetition rate. We also discuss extension of this system to the petawatt power level and potential applications in the relativistic, ultrahigh intensity regimes. (author)

Low Group Delay Dispersion Optical Coating for Broad Bandwidth High Reflection at 45° Incidence, P Polarization of Femtosecond Pulses with 900 nm Center Wavelength

Directory of Open Access Journals (Sweden)

John C. Bellum

2016-03-01

Full Text Available We describe an optical coating design suitable for broad bandwidth high reflection (BBHR at 45° angle of incidence (AOI, P polarization (Ppol of femtosecond (fs laser pulses whose wavelengths range from 800 to 1000 nm. Our design process is guided by quarter-wave HR coating properties. The design must afford low group delay dispersion (GDD for reflected light over the broad, 200 nm bandwidth in order to minimize temporal broadening of the fs pulses due to dispersive alteration of relative phases between their frequency components. The design should also be favorable to high laser-induced damage threshold (LIDT. We base the coating on TiO2/SiO2 layer pairs produced by means of e-beam evaporation with ion-assisted deposition, and use OptiLayer Thin Film Software to explore designs starting with TiO2/SiO2 layers having thicknesses in a reverse chirped arrangement. This approach led to a design with R > 99% from 800 to 1000 nm and GDD < 20 fs2 from 843 to 949 nm (45° AOI, Ppol. The design’s GDD behaves in a smooth way, suitable for GDD compensation techniques, and its electric field intensities show promise for high LIDTs. Reflectivity and GDD measurements for the initial test coating indicate good performance of the BBHR design. Subsequent coating runs with improved process calibration produced two coatings whose HR bands satisfactorily meet the design goals. For the sake of completeness, we summarize our previously reported transmission spectra and LIDT test results with 800 ps, 8 ps and 675 fs pulses for these two coatings, and present a table of the LIDT results we have for all of our TiO2/SiO2 BBHR coatings, showing the trends with test laser pulse duration from the ns to sub-ps regimes.

All-PM monolithic fs Yb-fiber laser, dispersion-managed with all-solid photonic bandgap fiber

DEFF Research Database (Denmark)

Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

2009-01-01

All-in-fiber SESAM-modelocked self-starting fiber laser is demonstrated. Cavity dispersion is managed by a spliced-in PM all-solid photonic bandgap fiber. The laser directly delivers 1.25 nJ pulses of 280 fs duration.......All-in-fiber SESAM-modelocked self-starting fiber laser is demonstrated. Cavity dispersion is managed by a spliced-in PM all-solid photonic bandgap fiber. The laser directly delivers 1.25 nJ pulses of 280 fs duration....

Simultaneous fabrication of laser-active colour centres and permanent microgratings in lithium fluoride by a single femtosecond pulse

International Nuclear Information System (INIS)

Kurobori, Toshio; Kawamura, Ken-ichi; Hirano, Masahiro; Hosono, Hideo

2003-01-01

We report, for the first time, simultaneous fabrication of laser-active F 2 and F 3 + colour centres in lithium fluoride and permanent periodic gratings with fringe spacings as fine as sub-micron size by two interfering infrared femtosecond (fs) laser pulses. In particular, the optical properties (absorption and luminescence) of F 2 and F 3 + colour centres produced by a single fs laser pulse are compared with those created by damage from radiation such as x-rays. The present technique of simultaneously fabricating laser-active colour centres and functional fine-periodic structures in photo-insensitive transparent materials may well be a useful method for making miniaturized optical devices. (letter to the editor)

Effects of oxygen partial pressure on the ferroelectric properties of pulsed laser deposited Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Silva, J.P.B.; Sekhar, K.C.; Pereira, M.; Gomes, M.J.M. [University of Minho, Centre of Physics, Braga (Portugal); Almeida, A.; Agostinho Moreira, J. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Fisica e Astronomia, Faculdade de Ciencias da Universidade do Porto, Porto (Portugal)

2013-11-15

The Ba{sub 0.8}Sr{sub 0.2}TiO{sub 3} thin films were grown on the Pt-Si substrate at 700 C by using a pulsed laser deposition technique at different oxygen partial pressure (PO{sub 2}) in the range of 1-20 Pa and their properties were investigated. It is observed that the PO{sub 2} during the deposition plays an important role on the tetragonal distortion ratio, surface morphology, dielectric permittivity, ferroelectric polarization, switching response, and leakage currents of the films. With an increase in PO{sub 2}, the in-plane strain for the BST films changes from tensile to compressive. The films grown at 7.5 Pa show the optimum dielectric and ferroelectric properties and also exhibit the good polarization stability. It is assumed that a reasonable compressive strain, increasing the ionic displacement, and thus promotes the in-plane polarization in the field direction, could improve the dielectric permittivity. The butterfly features of the capacitance-voltage (C-V) characteristics and the bell shape curve in polarization current were attributed to the domain reversal process. The effect of pulse amplitude on the polarization reversal behavior of the BST films grown at PO{sub 2} of 7.5 Pa was studied. The peak value of the polarization current shows exponential dependence on the electric field. (orig.)

Synchronization of sub-picosecond electron and laser pulses

International Nuclear Information System (INIS)

Rosenzweig, J.B.; Le Sage, G.P.

1999-01-01

Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail. (AIP) copyright 1999 American Institute of Physics

Numerical studies of acceleration of thorium ions by a laser pulse of ultra-relativistic intensity

Directory of Open Access Journals (Sweden)

Domanski Jaroslaw

2018-01-01

Full Text Available One of the key scientific projects of ELI-Nuclear Physics is to study the production of extremely neutron-rich nuclides by a new reaction mechanism called fission-fusion using laser-accelerated thorium (232Th ions. This research is of crucial importance for understanding the nature of the creation of heavy elements in the Universe; however, they require Th ion beams of very high beam fluencies and intensities which are inaccessible in conventional accelerators. This contribution is a first attempt to investigate the possibility of the generation of intense Th ion beams by a fs laser pulse of ultra-relativistic intensity. The investigation was performed with the use of fully electromagnetic relativistic particle-in-cell code. A sub-μm thorium target was irradiated by a circularly polarized 20-fs laser pulse of intensity up to 1023 W/cm2, predicted to be attainable at ELI-NP. At the laser intensity ~ 1023 W/cm2 and an optimum target thickness, the maximum energies of Th ions approach 9.3 GeV, the ion beam intensity is > 1020 W/cm2 and the total ion fluence reaches values ~ 1019 ions/cm2. The last two values are much higher than attainable in conventional accelerators and are fairly promising for the planned ELI-NP experiment.

Scintillation properties of (C sub 6 H sub 1 sub 3 NH sub 3) sub 2 PbI sub 4 Exciton luminescence of an organic/inorganic multiple quantum well structure compound induced by 2.0 MeV protons

CERN Document Server

Shibuya, K; Takeoka, Y; Asai, K

2002-01-01

We report a new type of scintillator especially suitable for pulse-radiation detection. Thin films of organic/inorganic perovskite compound (n-C sub 6 H sub 1 sub 3 NH sub 3) sub 2 PbI sub 4 , which is characterized by a multiple quantum well structure, were bombarded by 2.0 MeV protons, and their radiation-induced emission spectra were obtained. A single and sharp emission peak due to an exciton was observed at the wavelength of 524 nm. This emission was clearly detected even at room temperature, and its quantum efficiency was very high. The line shape of this emission did not change, retaining its sharpness, and no other emissions appeared throughout the irradiation. The optical response of (n-C sub 6 H sub 1 sub 3 NH sub 3) sub 2 PbI sub 4 is very fast. (n-C sub 6 H sub 1 sub 3 NH sub 3) sub 2 PbI sub 4 is a promising scintillator material, meeting requirements not satisfied by conventional scintillators.

Structure and physical properties of RT{sub 2}Cd{sub 20} (R=rare earth, T=Ni, Pd) compounds with the CeCr{sub 2}Al{sub 20}-type structure

Energy Technology Data Exchange (ETDEWEB)

Burnett, V.W.; Yazici, D.; White, B.D. [Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093 (United States); Dilley, N.R. [Quantum Design, 6325 Lusk Boulevard, San Diego, CA 92121 (United States); Friedman, A.J.; Brandom, B. [Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093 (United States); Maple, M.B., E-mail: mbmaple@physics.ucsd.edu [Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, CA 92093 (United States)

2014-07-01

Eleven new compounds, R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) and R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm), were grown as single crystals in high temperature cadmium-rich solutions. They crystallize in the cubic CeCr{sub 2}Al{sub 20}-type structure (Fd3{sup ¯}m, Z=8) as characterized by measurements of powder X-ray diffraction. Electrical resistivity, magnetization, and specific heat measurements were performed on R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals. Whereas YNi{sub 2}Cd{sub 20} and LaNi{sub 2}Cd{sub 20} exhibit unremarkable metallic behavior, when magnetic moments from localized 4f electron states (Gd{sup 3+}–Tb{sup 3+}) are embedded into this host, they exhibit ferromagnetic order with values of the Curie temperature T{sub C} for R Ni{sub 2}Cd{sub 20} (R=Gd, and Tb) which scale with the de Gennes factor. - Graphical abstract: Specific heat divided by temperature C/T vs. T for single crystals of R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Gd, and Tb). Left inset: Low temperature C/T vs. T{sup 2} for LaNi{sub 2}Cd{sub 20}. The solid line represents a linear fit of the data. Right inset: Low-temperature C/T data vs. T for R=Ce–Nd, Gd, and Tb; magnetic ordering temperatures are indicated by arrows. - Highlights: • R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals synthesized for the first time. • R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm) single crystals synthesized for the first time. • Single crystals are of good metallurgical quality (large RRR values). • NdNi{sub 2}Cd{sub 20} orders antiferromagnetically at T{sub N}=1.5 K. • R Ni{sub 2}Cd{sub 20} (R=Sm, Gd, Tb) order ferromagnetically.

Measurement of the C{sub 2}H{sub 2} destruction kinetics by infrared laser absorption spectroscopy in a pulsed low pressure dc discharge

Energy Technology Data Exchange (ETDEWEB)

Rousseau, A [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Guaitella, O [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Gatilova, L [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Hannemann, M [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany); Roepcke, J [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany)

2007-04-07

The kinetics of destruction of C{sub 2}H{sub 2} is investigated in a low pressure pulsed dc discharge in dry air. Tuneable diode laser absorption spectroscopy in the mid-infrared region (1350 cm{sup -1}) has been used to measure the influence of (i) the pulse duration (ii) the pulse repetition rate and (iii) the pulse current on the C{sub 2}H{sub 2} concentration in situ the discharge tube. First, it is shown that in the plasma region under flow conditions the time averaged concentration of C{sub 2}H{sub 2} depends only on the time averaged discharge current. Second, time resolved measurements have been performed in a closed reactor, i.e. under static conditions. A simple kinetic modelling of the pulsed discharge leads to a good agreement with the experimental results and shows that the oxidation rate of C{sub 2}H{sub 2} is mainly controlled by the time averaged concentration of O atoms. Finally, the influence of porous TiO{sub 2} photocatalyst on the C{sub 2}H{sub 2} oxidation rate is reported.

Sub-50 fs excited state dynamics of 6-chloroguanine upon deep ultraviolet excitation.

Science.gov (United States)

Mondal, Sayan; Puranik, Mrinalini

2016-05-18

The photophysical properties of natural nucleobases and their respective nucleotides are ascribed to the sub-picosecond lifetime of their first singlet states in the UV-B region (260-350 nm). Electronic transitions of the ππ* type, which are stronger than those in the UV-B region, lie at the red edge of the UV-C range (100-260 nm) in all isolated nucleobases. The lowest energetic excited states in the UV-B region of nucleobases have been investigated using a plethora of experimental and theoretical methods in gas and solution phases. The sub-picosecond lifetime of these molecules is not a general attribute of all nucleobases but specific to the five primary nucleobases and a few xanthine and methylated derivatives. To determine the overall UV photostability, we aim to understand the effect of more energetic photons lying in the UV-C region on nucleobases. To determine the UV-C initiated photophysics of a nucleobase system, we chose a halogen substituted purine, 6-chloroguanine (6-ClG), that we had investigated previously using resonance Raman spectroscopy. We have performed quantitative measurements of the resonance Raman cross-section across the Bb absorption band (210-230 nm) and constructed the Raman excitation profiles. We modeled the excitation profiles using Lee and Heller's time-dependent theory of resonance Raman intensities to extract the initial excited state dynamics of 6-ClG within 30-50 fs after photoexcitation. We found that imidazole and pyrimidine rings of 6-ClG undergo expansion and contraction, respectively, following photoexcitation to the Bb state. The amount of distortions of the excited state structure from that of the ground state structure is reflected by the total internal reorganization energy that is determined at 112 cm(-1). The contribution of the inertial component of the solvent response towards the total reorganization energy was obtained at 1220 cm(-1). In addition, our simulation also yields an instantaneous response of the first

An Ultra Low Noise Self-Starting Pulse Generator

DEFF Research Database (Denmark)

Lasri, J.; Bilenca, A.; Dahan, D.

2002-01-01

We describe a self-starting optical pulse source generating 10 GHz, 15 ps pulses with an average jitter of 43 fs and a o.15% amplitude noise over a frequency range of 500 Hz - 1 MHz.......We describe a self-starting optical pulse source generating 10 GHz, 15 ps pulses with an average jitter of 43 fs and a o.15% amplitude noise over a frequency range of 500 Hz - 1 MHz....

Preparation of supported heterogeneous catalysts by pulse impregnation: Application to Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst

Energy Technology Data Exchange (ETDEWEB)

Haukka, M.; Pakkanen, T.A. (Univ. of Joensuu (Finland))

1994-07-01

In this paper, the authors introduce pulse impregnation, a method for preparing supported heterogeneous catalysts by successive impregnation cycles. Pulse impregnation is a method for preparing supported heterogeneous catalysts from the liquid phase. In the pulse-impregnation technique the catalyst surface is grown gradually in consecutive cycles, with each cycle consisting of separate deposition and activation steps. During the deposition step, the catalyst precursor or precursors are deposited onto the support from a suitable solvent. The actual chemically bonded catalyst phase is formed during the activation step (e.g., thermal activation). Pulse impregnation was tested in the separate deposition of 2,2[prime]-bipyridine and Ru[sub 3](CO)[sub 12] onto a silica support, and in the preparation of Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst, in a column-type reactor system. Macroscopically uniform deposition was achieved with both 2,2[prime]-bipyridine and Ru[sub 3](CO)[sub 12]. Various solvent systems were used to control the amount of solute adsorbed during deposition. In the preparation of the Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst, the ruthenium content increased nearly linearly with the number of preparation cycles. The effects of the preparation method on the catalyst activity was also tested in 1-hexane hydroformylation. 31 refs., 7 figs., 1 tab.

Pleiades: A Sub-picosecond Tunable X-ray Source at the LLNL Electron Linac

International Nuclear Information System (INIS)

Slaughter, Dennis; Springer, Paul; Le Sage, Greg; Crane, John; Ditmire, Todd; Cowan, Tom; Anderson, Scott G.; Rosenzweig, James B.

2002-01-01

The use of ultra fast laser pulses to generate very high brightness, ultra short (fs to ps) pulses of x-rays is a topic of great interest to the x-ray user community. In principle, femto-second-scale pump-probe experiments can be used to temporally resolve structural dynamics of materials on the time scale of atomic motion. The development of sub-ps x-ray pulses will make possible a wide range of materials and plasma physics studies with unprecedented time resolution. A current project at LLNL will provide such a novel x-ray source based on Thomson scattering of high power, short laser pulses with a high peak brightness, relativistic electron bunch. The system is based on a 5 mm-mrad normalized emittance photo-injector, a 100 MeV electron RF linac, and a 300 mJ, 35 fs solid-state laser system. The Thomson x-ray source produces ultra fast pulses with x-ray energies capable of probing into high-Z metals, and a high flux per pulse enabling single shot experiments. The system will also operate at a high repetition rate (∼ 10 Hz). (authors)

Glass formation ability, structure and magnetocaloric effect of a heavy rare-earth bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy

Energy Technology Data Exchange (ETDEWEB)

Jo, C.-L. [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)], E-mail: jochollong@163.com; Xia Lei; Ding Ding; Dong Yuanda; Gracien, Ekoko [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)

2008-06-30

The glass formation ability, the structure and the magnetocaloric effect of the bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy were investigated. Bulk metallic glassy (BMGs) alloys were prepared by a copper-mold casting method. The glass forming ability and their structure were studied by using X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The XRD analysis revealed that the as-cast cylinder of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed fully amorphous structure in 2 mm diameter. The DSC revealed that the bulk cylinder of the Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed a distinct glass transition temperature and a relatively wide supercooled liquid region before crystallization. SQUID investigated the magnetic properties and the entropy changes. The Curie temperature of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} BMGs alloy was about 130 K, but the maximum magnetic entropy changes(-{delta}S{sub M}) showed at about 125 K, a little lower than the Curie temperature 130 K. The reason could probably be due to the presence of a little amount of nanocrystalline particles between amorphous phases. The BMG alloy has the characteristic of second-order transition (SOT) on Arrott plots. The results showed that the amorphous sample had a relatively improved magnetocaloric effect, indicating that the amorphous alloy could be considered as a candidate for magnetic refrigeration applications in the temperature interval range of 100-200 K.

Effect of pulse current parameters on microstructure of tungsten coating electroplated from Na{sub 2}WO{sub 4}–WO{sub 3}–NaPO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Jiang, Fan; Zhang, Yingchun, E-mail: zycustb@163.com; Sun, Ningbo; Len, Jiaxun

2015-03-15

Highlights: • Tungsten coatings were electroplated on cooper alloy by pulse plating. • Increasing current density resulted in an increase in grain size of tungsten coating. • With the increase in duty cycle, the grain size of tungsten coating increased. • The pulse period had an insignificant effect on the tungsten grain size. - Abstract: The tungsten coatings with low oxygen content were prepared on copper alloy substrate by pulse electroplating in Na{sub 2}WO{sub 4}–WO{sub 3}–NaPO{sub 3} molten salt. A series of tungsten coatings with compact morphologies were successfully obtained under various conditions. The influences of current density, duty cycle and period on tungsten grain size and coatings thickness were investigated. The results demonstrated that current density was the most important factor influencing tungsten grain size, which had a positive correlation with current density. The thickness of coating decreased when the current density was up to 80 mA cm{sup −2}. However, the tungsten grain size, tungsten coating thickness and current efficiency changed a little with the increase in pulse periods.

Hybrid fs/ps CARS for Sooting and Particle-laden Flames [PowerPoint

Energy Technology Data Exchange (ETDEWEB)

Hoffmeister, Kathryn N. Gabet; Guildenbecher, Daniel Robert; Kearney, Sean P.

2016-01-01

We report the application of ultrafast rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning aluminized ammonium perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laserbased diagnostics, with intense background luminosity, scattering and beam obstruction from hot metal particles that can be as large as several hundred microns in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminumparticle- seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulateenhanced laser-induced breakdown. Introduction of fs/ps laser pulses enables CARS detection at reduced pulse energies, decreasing the likelihood of breakdown, while simultaneously providing time-gated elimination of any nonresonant background interference. Temperature probability densities and temperature/oxygen correlations were constructed from ensembles of several thousand single-laser-shot measurements from the fs/ps rotational CARS measurement volume positioned within 3 mm or less of the burning propellant surface. Preliminary results in canonical flames are presented using a hybrid fs/ps vibrational CARS system to demonstrate our progress towards acquiring vibrational CARS measurements for more accurate temperatures in the very high temperature propellant burns.

Yttrium-enriched YBa{sub 2}Cu{sub 3}O{sub x} thin films for coated conductors fabricated by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Khoryushin, Alexey V., E-mail: khoryushin@ya.ru [Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Mozhaev, Peter B.; Mozhaeva, Julia E.; Andersen, Niels H. [Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Grivel, Jean-Claude [Department of Energy Conversion and Storage, Technical University of Denmark, DK-4000 Roskilde (Denmark); Hansen, Jørn Bindslev; Jacobsen, Claus S. [Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

2013-02-14

Highlights: ► YBCO films were fabricated by PLD from targets of various elemental compositions. ► The Y-enriched films contain yttria nanoparticles which provide efficient pinning. ► The best film has 5.5× higher j{sub c}(5 T,50 K) = 2.6MA/cm{sup 2} comparing with a reference film. ► The Y-enriched films remain c-oriented up to 500 nm. ► Films demonstrate no j{sub c} suppression with thickness and remarkable stability with time. -- Abstract: The effects of excess yttria on the structural and electrical properties of the YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) thin films are studied. The films were deposited on (LaAlO{sub 3}){sub 0.3}–(Sr{sub 2}AlTaO{sub 8}){sub 0.7} substrates by pulsed laser ablation from targets with different elemental composition. An increase of yttrium content of the target leads to formation of porous films with significantly improved current-carrying capabilities. Structural studies of these films reveal presence of yttria nanoparticles embedded into the YBCO matrix. The highest obtained critical current density in an external magnetic field of 5 T was 2.6 MA/cm{sup 2} at 50 K and 9.4 MA/cm{sup 2} at 20 K. The fabricated Y-enriched YBCO films remain c-oriented at least up to 600 nm thickness with no significant suppression of the critical current density.

A 66 fs highly stable single wall carbon nanotube mode locked fiber laser

International Nuclear Information System (INIS)

Yu, Zhenhua; Zhang, Xiao; Dong, Xinzheng; Tian, Jinrong; Song, Yanrong; Wang, Yonggang

2014-01-01

We demonstrate a highly stable mode locked fiber laser based on single wall carbon nanotubes. The mode locking is achieved by the evanescent field interaction of the propagating light with a single wall carbon nanotube saturable absorber in a microfiber. The pulse width is 66 fs, which, to the best of our knowledge, is the shortest pulse achieved in a carbon nanotube mode locked fiber laser. The maximum average output power is 26 mW, which is about 20 times larger than that of a typical carbon nanotube mode locked fiber laser. The center of the wavelength is 1555 nm, with 54 nm spectral width. The repetition rate is 146 MHz. To investigate the laser’s stability, the output pulses are monitored for 120 h and there is no significant degradation of the laser spectral width or shape. (paper)

Photonics at the frontiers. Generation of few-cycle light pulses via NOPCPA and real-time probing of charge transfer in hybrid photovoltaics

Energy Technology Data Exchange (ETDEWEB)

Herrmann, Daniel

2011-11-11

In the first part of this thesis the methodics of the non-collinear, optically parametric amplification of chirped light pulses (NOPCPA) for the generation of few-cycle light pulses in the visible (Vis) and near infrared (NIR) with of 5-8 fs half-width are essential further developed. Fundamental parametric influences, like the existence of a parametrically induced phase and the generation of optically parametric fluorescence (OPF), are studied both by theoretical analyses and numerical simulations and by concrete experiments. Experimentally in the framework of this thesis fwe-cycle light pulses with a pulse width of 7.9 fs, 130 mJ energy, at 805 nm central wavelength and a very high seed-pulse-limited prepulse contrast of 11 and 8 orders of magnitude are reached at 30 ps and approximately 3 ps. One the one hand it has been succeeded to accelerate with the broad-band pulse amplifier quasi-monoenergetic electrons with energies of up to 50 MeV. For this the light pulse is focussed to relativistic intensities of several W/cm{sup 2} in a helium gas jet. On the other hand XUV light was produced up to the 20th harmonic of the generated light pulse from the broad-band pulse amplifier by its sub-cycle interaction with solid surfaces. In the framework of this thesis furthermore new, extended concepts for still broader-band NOPCPA over one octave were developed and characterized, which contain the application of two pump pulses in one NOPCPA stage and the application of two different pump wavelength in two subsequent NOPCPA stages. In the second part of this thesis broad-band white-light spectra and by means of NOPCPA spectrally tunable light pulses are applied in order to realize a transient absorption spectrometer with multichannel detection. This new excitation-query construction combines a very broad-band UV-Vis-NIR query with a high time resolution of 40 fs and high sensitivity for the transient change of the optical density of less than 10{sup -4}. By this it has in

EST Table: FS875608 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS875608 E_FL_ftes_04F20_F_0 10/09/28 45 %/153 aa ref|XP_973163.1| PREDICTED: similar to jump...45 %/151 aa gnl|Amel|GB14856-PA 10/09/10 45 %/153 aa gi|91086783|ref|XP_973163.1| PREDICTED: similar to jumping translocation breakpoint protein [Tribolium castaneum] FS906679 ftes ...

EST Table: FS891805 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS891805 E_FL_ftes_04F20_R_0 10/09/28 46 %/153 aa ref|XP_973163.1| PREDICTED: similar to jump...46 %/151 aa gnl|Amel|GB14856-PA 10/09/10 46 %/153 aa gi|91086783|ref|XP_973163.1| PREDICTED: similar to jumping translocation breakpoint protein [Tribolium castaneum] FS891321 ftes ...

EST Table: FS862828 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS862828 E_FL_fner_20A08_R_0 10/09/28 46 %/153 aa ref|XP_973163.1| PREDICTED: similar to jump...46 %/151 aa gnl|Amel|GB14856-PA 10/09/10 46 %/153 aa gi|91086783|ref|XP_973163.1| PREDICTED: similar to jumping translocation breakpoint protein [Tribolium castaneum] FS891321 fner ...

EST Table: FS844168 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS844168 E_FL_fner_20A08_F_0 10/09/28 45 %/153 aa ref|XP_973163.1| PREDICTED: similar to jump...45 %/151 aa gnl|Amel|GB14856-PA 10/09/10 45 %/153 aa gi|91086783|ref|XP_973163.1| PREDICTED: similar to jumping translocation breakpoint protein [Tribolium castaneum] FS906679 fner ...

On the 2nd order autocorrelation of an XUV attosecond pulse train

International Nuclear Information System (INIS)

Tzallas, P.; Benis, E.; Nikolopoulos, L.A.A.; Tsakiris, G.D.; Witte, K.; Charalambidis, P

2005-01-01

Full text: We present the first direct measurement of sub-fs light bunching that has been achieved, extending well established fs optical metrology to XUV as pulses. A mean train pulse duration of 780 as has been extracted through a 2 nd order autocorrelation approach, utilizing a nonlinear effect that is induced solely by the XUV radiation to be characterized. The approach is based on (i) a bisected spherical mirror XUV wavefront divider used as an autocorrelator and (ii) the two photon ionization of atomic He by a superposition of the 7 th to the 15 th harmonic of a Ti:sapph laser. The measured temporal mean width is more than twice its Fourier transform limited (FTL) value, in contrast to the as train pulse durations measured through other approaches, which where found much closer to the FTL values. We have investigated, and discuss here the origin of this discrepancy. An assessment of the validity of the 2 nd order AC approach for the broad band XUV radiation of as pulses is implemented through ab initio calculations (solution of the 3D TDSE of He in the presence of the superposition of the harmonic superposition) modeling the spectral and temporal response of the two-XUV-photon He ionization detector employed. It is found that both the spectral and temporal response are not affecting the measured duration. The mean width of the as train bursts is estimated from the spectral phases of the individual harmonics as they result from the rescattering model, taking into account the spatially modulated temporal width of the radiation due to the spatiotemporal intensity distribution of the driving field during the harmonic generation process. The measured value is found in reasonable agreement with the estimated duration. The method used for the 2 nd order AC in itself initiates further XUV-pump-XUV-probe studies of sub-fs-scale dynamics and at the same time becomes highly pertinent in connection with nonlinear experiments using XUV free - electron laser sources. Refs

Emission factors and congener-specific characterization of PCDD/Fs, PCBs, PBDD/Fs and PBDEs from an off-road diesel engine using waste cooking oil-based biodiesel blends.

Science.gov (United States)

Chen, Shui-Jen; Tsai, Jen-Hsiung; Chang-Chien, Guo-Ping; Huang, Kuo-Lin; Wang, Lin-Chi; Lin, Wen-Yinn; Lin, Chih-Chung; Yeh, C Kuei-Jyum

2017-10-05

Few studies have been performed up to now on the emission factors and congener profiles of persistent organic pollutants (POPs) emitted from off-road diesel engines. This investigation elucidates the emission factors and congener profiles of various POPs, namely polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyl (PCBs), polybrominated dibenzo-p-dioxins and polybrominated dibenzofurans (PBDD/Fs) and polybrominated diphenyl ethers (PBDEs), in the exhausts of a diesel generator fueled with different waste cooking oil-based biodiesel (WCO-based biodiesel) blends. The PCDD/Fs contributed 87.2% of total dioxin-like toxicity (PCDD/Fs+PCBs+PBDD/Fs) in the exhaust, while the PCBs and PBDD/Fs only contributed 8.2% and 4.6%, respectively. Compared with petroleum diesel, B20 (20vol% WCO-based biodiesel+80vol% diesel) reduced total toxicity by 46.5% for PCDD/Fs, 47.1% for PCBs, and 24.5% for PBDD/Fs, while B40 (40vol% WCO-based biodiesel+60vol% diesel) reduced it by 89.5% for PCDD/Fs, 57.1% for PCBs, and 63.2% for PBDD/Fs in POP emission factors. The use of WCO-based biodiesel not only solves the problem of waste oil disposal, but also lowers POP emissions from diesel generators. Copyright © 2017 Elsevier B.V. All rights reserved.

Damage Mechanisms In Polymers Upon NIR Femtosecond Pulse Laser Irradiation: Sub-Threshold Processes And Their Implications For Laser Safety Applications

International Nuclear Information System (INIS)

Bonse, Joern; Krueger, Joerg; Solis, Javier; Spielmann, Christian; Lippert, Thomas

2010-01-01

This contribution investigates laser-induced damage of thin film and bulk polymer samples, with the focus on physical processes occurring close to the damage threshold. In-situ real-time reflectivity (RTR) measurements with picosecond (ps) and nanosecond (ns) temporal resolution were performed on thin polymer films on a timescale up to a few microseconds (μs). A model for polymer thin film damage is presented, indicating that irreversible chemical modification processes take place already below the fluence threshold for macroscopic damage. On dye-doped bulk polymer filters (as used for laser goggles), transmission studies using fs-and ps-laser pulses reveal the optical saturation behavior of the material and its relation to the threshold of permanent damage. Implications of the sub-threshold processes for laser safety applications will be discussed for thin film and bulk polymer damage.

Design and implementation of an optimal laser pulse front tilting scheme for ultrafast electron diffraction in reflection geometry with high temporal resolution

Directory of Open Access Journals (Sweden)

Francesco Pennacchio

2017-07-01

Full Text Available Ultrafast electron diffraction is a powerful technique to investigate out-of-equilibrium atomic dynamics in solids with high temporal resolution. When diffraction is performed in reflection geometry, the main limitation is the mismatch in group velocity between the overlapping pump light and the electron probe pulses, which affects the overall temporal resolution of the experiment. A solution already available in the literature involved pulse front tilt of the pump beam at the sample, providing a sub-picosecond time resolution. However, in the reported optical scheme, the tilted pulse is characterized by a temporal chirp of about 1 ps at 1 mm away from the centre of the beam, which limits the investigation of surface dynamics in large crystals. In this paper, we propose an optimal tilting scheme designed for a radio-frequency-compressed ultrafast electron diffraction setup working in reflection geometry with 30 keV electron pulses containing up to 105 electrons/pulse. To characterize our scheme, we performed optical cross-correlation measurements, obtaining an average temporal width of the tilted pulse lower than 250 fs. The calibration of the electron-laser temporal overlap was obtained by monitoring the spatial profile of the electron beam when interacting with the plasma optically induced at the apex of a copper needle (plasma lensing effect. Finally, we report the first time-resolved results obtained on graphite, where the electron-phonon coupling dynamics is observed, showing an overall temporal resolution in the sub-500 fs regime. The successful implementation of this configuration opens the way to directly probe structural dynamics of low-dimensional systems in the sub-picosecond regime, with pulsed electrons.

Pulsed inductive HF laser

Energy Technology Data Exchange (ETDEWEB)

Razhev, A M; Kargapol' tsev, E S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation); Churkin, D S; Demchuk, S V [Novosibirsk State University, Novosibirsk (Russian Federation)

2016-03-31

We report the results of experimentally investigated dependences of temporal, spectral and spatial characteristics of an inductive HF-laser generation on the pump conditions. Gas mixtures H{sub 2} – F{sub 2}(NF{sub 3} or SF6{sub 6}) and He(Ne) – H{sub 2} – F{sub 2}(NF{sub 3} or SF{sub 6}) were used as active media. The FWHM pulse duration reached 0.42 μs. This value corresponded to a pulsed power of 45 kW. For the first time, the emission spectrum of an inductive HF laser was investigated, which consisted of seven groups of bands with centres around the wavelengths of 2732, 2736, 2739, 2835, 2837, 2893 and 2913 nm. The cross section profile of the laser beam was a ring with a diameter of about 20 mm and width of about 5 mm. Parameters of laser operation in the repetitively pulsed regime were sufficiently stable. The amplitude instability of light pulses was no greater than 5% – 6%. (lasers)

Rietveld profile analysis of calcined AlPO/sub 4/-11 using pulsed neutron powder diffraction

Energy Technology Data Exchange (ETDEWEB)

Richardson, J.W. Jr.; Pluth, J.J.; Smith, J.V.

1988-08-01

Aluminium phosphate, AlPO/sub 4/, M/sub r/=121.95, orthorhombic, Icmm (disordered Al, P), Icm2 (ordered Al, P), a=13.5333(8), b=18.4845(10), c=8.3703(4) A, V=2094 A/sup 3/, Z=20, D/sub x/=1.93 g cm/sup -3/, T approx. = 295 K, R/sub wp/=0.031, R/sub F//sup 2/=0.109 (Icmm) and R/sub wp/=0.027, R/sub F//sup 2/=0.058 (Icm2) for 1017 independent reflections. Sample calcined at 873 K and dehydrated at 573 K. Time-of-flight neutron powder diffraction data were taken on the GPPD diffractometer at the Argonne National Laboratory Intense Pulsed Neutron Source. The structure was refined by Rietveld profile analysis in the range d=0.86-3.91 A in two space groups: Icmm assuming no ordering of Al and P, and Icm2 assuming strict alternation of Al and P on tetrahedral nodes. (orig./BHo).

SeaWiFS technical report series. Volume 26: Results of the SeaWiFS Data Analysis Round-Robin, July 1994 (DARR-1994)

Science.gov (United States)

Hooker, Stanford B. (Editor); Firestone, Elaine R. (Editor); Siegel, David A.; Obrien, Margaret C.; Sorensen, Jen C.; Konnoff, Daniel A.; Brody, Eric A.; Mueller, James L.; Davis, Curtiss O.; Rhea, W. Joseph

1995-01-01

The accurate determination of upper ocean apparent optical properties (AOP's) is essential for the vicarious calibration of the sea-viewing wide field-of-view sensor (SeaWiFS) instrument and the validation of the derived data products. To evaluate the role that data analysis methods have upon values of derived AOP's, the first Data Analysis Round-Robin (DARR-94) workshop was sponsored by the SeaWiFS Project during 21-23 July, 1994. The focus of this intercomparison study was the estimation of the downwelling irradiance spectrum just beneath the sea surface, E(sub d)(0(sup -), lambda); the upwelling nadir radiance just beneath the sea surface, L(sub u)(0(sup -), lambda); and the vertical profile of the diffuse attenuation coefficient spectrum, K(sub d)(z, lambda). In the results reported here, different methodologies from four research groups were applied to an identical set of 10 spectroradiometry casts in order to evaluate the degree to which data analysis methods influence AOP estimation, and whether any general improvements can be made. The overall results of DARR-94 are presented in Chapter 1 and the individual methods of the four groups are presented in Chapters 2-5. The DARR-94 results do not show a clear winner among data analysis methods evaluated. It is apparent, however, that some degree of outlier rejection is required in order to accurately estimate L(sub u)(0(sup -), lambda) or E(sub d)(0(sup -), lambda). Furthermore, the calculation, evaluation and exploitation of confidence intervals for the AOP determinations needs to be explored. That is, the SeaWiFS calibration and validation problem should be recast in statistical terms where the in situ AOP values are statistical estimates with known confidence intervals.

Analytical performances of laser-induced micro-plasma of Al samples with single and double ultrashort pulses in air and with Ar-jet: A comparative study

International Nuclear Information System (INIS)

Semerok, A.; Dutouquet, C.

2014-01-01

Ultrashort pulse laser microablation coupled with optical emission spectroscopy was under study to obtain several micro-LIBS analytical features (shot-to-shot reproducibility, spectral line intensity and lifetime, calibration curves, detection limits). Laser microablation of Al matrix samples with known Cu- and Mg-concentrations was performed by single and double pulses of 50 fs and 1 ps pulse duration in air and with Ar-jet. The micro-LIBS analytical features obtained under different experimental conditions were characterized and compared. The highest shot-to-shot reproducibility and gain in plasma spectral line intensity were obtained with double pulses with Ar-jet for both 50 fs and 1 ps pulse durations. The best calibration curves were obtained with 1 ps pulse duration with Ar-jet. Micro-LIBS with ultrashort double pulses may find its effective application for surface elemental microcartography. - Highlights: • Analytical performances of micro-LIBS with ultrashort double pulses were studied. • The maximal line intensity gain of 20 was obtained with double pulses and Ar-jet. • LIBS gain was obtained without additional ablation of a sample by the second pulse. • LIBS properties were almost the same for both 50 fs and 1 ps pulses. • The micro-LIBS detection limit was around 35 ppm

Single-shot 35 fs temporal resolution electron shadowgraphy

Energy Technology Data Exchange (ETDEWEB)

Scoby, C. M.; Li, R. K.; Threlkeld, E.; To, H.; Musumeci, P. [Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States)

2013-01-14

We obtain single-shot time-resolved shadowgraph images of the electromagnetic fields resulting from the interaction of a high intensity ultrashort laser pulse with a metal surface. Using a high brightness relativistic electron beam and a high streaking speed radiofrequency deflector, we report <35 fs temporal resolution enabling a direct visualization of the retarded-time dominated field evolution which follows the laser-induced charge emission. A model including the finite signal propagation speed well reproduces the data and yields measurements of fundamental parameters in short pulse laser-matter interaction such as the amount of emitted charge and the emission time scale.

Single-shot 35 fs temporal resolution electron shadowgraphy

International Nuclear Information System (INIS)

Scoby, C. M.; Li, R. K.; Threlkeld, E.; To, H.; Musumeci, P.

2013-01-01

We obtain single-shot time-resolved shadowgraph images of the electromagnetic fields resulting from the interaction of a high intensity ultrashort laser pulse with a metal surface. Using a high brightness relativistic electron beam and a high streaking speed radiofrequency deflector, we report <35 fs temporal resolution enabling a direct visualization of the retarded-time dominated field evolution which follows the laser-induced charge emission. A model including the finite signal propagation speed well reproduces the data and yields measurements of fundamental parameters in short pulse laser-matter interaction such as the amount of emitted charge and the emission time scale.

EST Table: FS924814 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS924814 E_FL_fwgP_11K20_F_0 10/09/28 39 %/114 aa ref|NP_001129360.1| osiris 9 [Bom...byx mori] gb|ACI23620.1| osiris 9 [Bombyx mori] 10/09/13 n.h 10/08/29 n.h 10/09/10 n.h 10/09/10 n.h 10/09/10 n.h FS935058 fwgP ...

EST Table: FS912585 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS912585 E_FL_fufe_26K20_F_0 10/09/28 100 %/191 aa ref|NP_001098700.1| nanos-M [Bom...byx mori] dbj|BAF73619.1| nanos-M [Bombyx mori] 10/09/12 low homology 10/08/29 n.h 10/09/10 low homology 10/09/10 low homology 10/09/10 n.h FS918893 fufe ...

Fragmentation dynamics of molecular hydrogen in strong ultrashort laser pulses

International Nuclear Information System (INIS)

Rudenko, A; Feuerstein, B; Zrost, K; Jesus, V L B de; Ergler, T; Dimopoulou, C; Schroeter, C D; Moshammer, R; Ullrich, J

2005-01-01

We present the results of a systematic experimental study of dissociation and Coulomb explosion of molecular hydrogen induced by intense ultrashort (7-25 fs) laser pulses. Using coincident recoil-ion momentum spectroscopy we can distinguish the contributions from dissociation and double ionization even if they result in the same kinetic energies of the fragments. The dynamics of all fragmentation channels drastically depends on the pulse duration, and for 7 fs pulses becomes extremely sensitive to the pulse shape

Design of a bolometer for total-energy measurement of the linear coherent light source pulsed X-ray laser

Energy Technology Data Exchange (ETDEWEB)

Friedrich, S. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States)]. E-mail: Friedrich1@llnl.gov; Li, L. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Ott, L.L. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Kolgani, Rajeswari M. [Department of Physics, Geosciences and Astronomy, Towson University, 8000 York Avenue, Towson MD 21252 (United States); Yong, G.J. [Department of Physics, Geosciences and Astronomy, Towson University, 8000 York Avenue, Towson MD 21252 (United States); Ali, Z.A. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Drury, O.B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Ables, E. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States); Bionta, R.M. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550 (United States)

2006-04-15

We are developing a cryogenic bolometer to measure the total energy of the linear coherent light source (LCLS) free electron X-ray laser to be built at the Stanford Linear Accelerator Center. The laser will produce ultrabright X-ray pulses in the energy range between 0.8 and 8 keV with {approx}10{sup 12} photons per {approx}200 fs pulse at a repeat interval of 8 ms, and will be accompanied by a halo of spontaneous undulator radiation. The bolometer is designed to determine the total energy of each laser pulse to within <0.1%, taking into account thermal and mechanical stress to prevent melting in the LCLS beam due to its high energy density. We propose to use a magnetoresistive Nd{sub (1-} {sub x} {sub )}Sr {sub x} MnO{sub 3} sensor array at the metal-insulator transition, where the composition x is adjusted to produce the desired transition temperature. We discuss design considerations and material choices, and present numerical simulations of the thermal response.

Fs-laser processing of polydimethylsiloxane

Energy Technology Data Exchange (ETDEWEB)

Atanasov, Petar A., E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Shose, Sofia 1784 (Bulgaria); Valova, Eugenia I.; Georgieva, Zhenya S.; Armyanov, Stefan A.; Kolev, Konstantin N. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria); Amoruso, Salvatore; Wang, Xuan; Bruzzese, Ricardo [CNR-SPIN, Dipartimento di Scienze Fisiche, Universita degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Sawczak, Miroslaw; Śliwiński, Gerard [Photophysics Department, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St, 80-231 Gdańsk (Poland)

2014-07-14

We present an experimental analysis on surface structuring of polydimethylsiloxane films with UV (263 nm) femtosecond laser pulses, in air. Laser processed areas are analyzed by optical microscopy, SEM, and μ-Raman spectroscopy. The laser-treated sample shows the formation of a randomly nanostructured surface morphology. μ-Raman spectra, carried out at both 514 and 785 nm excitation wavelengths, prior and after laser treatment allow evidencing the changes in the sample structure. The influence of the laser fluence on the surface morphology is studied. Finally, successful electro-less metallization of the laser-processed sample is achieved, even after several months from the laser-treatment contrary to previous observation with nanosecond pulses. Our findings address the effectiveness of fs-laser treatment and chemical metallization of polydimethylsiloxane films with perspective technological interest in micro-fabrication devices for MEMS and nano-electromechanical systems.

Direct writing of sub-wavelength ripples on silicon using femtosecond laser at high repetition rate

International Nuclear Information System (INIS)

Xie, Changxin; Li, Xiaohong; Liu, Kaijun; Zhu, Min; Qiu, Rong; Zhou, Qiang

2016-01-01

Graphical abstract: - Highlights: • The NSRs and DSRs are obtained on silicon surface. • With increasing direct writing speed, the NSRs suddenly changes and becomes the DSRs. • We develop a Sipe–Drude interference theory by considering the thermal excitation. - Abstract: The near sub-wavelength and deep sub-wavelength ripples on monocrystalline silicon were formed in air by using linearly polarized and high repetition rate femtosecond laser pulses (f = 76 MHz, λ = 800 nm, τ = 50 fs). The effects of laser pulse energy, direct writing speed and laser polarization on silicon surface morphology are studied. When the laser pulse energy is 2 nJ/pulse and the direct writing speed varies from 10 to 25 mm/s, the near sub-wavelength ripples (NSRs) with orientation perpendicular to the laser polarization are generated. While the direct writing speed reaches 30 mm/s, the direction of the obtained deep sub-wavelength ripples (DSRs) suddenly changes and becomes parallel to the laser polarization, rarely reported so far for femtosecond laser irradiation of silicon. Meanwhile, we extend the Sipe–Drude interference theory by considering the thermal excitation, and numerically calculate the efficacy factor for silicon irradiated by femtosecond laser pulses. The revised Sipe–Drude interference theoretical results show good agreement with the periods and orientations of sub-wavelength ripples.

Structural and electronic properties of Pb-doped Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}: Comparison of LDA and GGA calculations

Energy Technology Data Exchange (ETDEWEB)

Camargo-Martínez, J.A., E-mail: jcamargo@unitropico.edu.co [Grupo de Investigación en Ciencias Básicas, Aplicación e Innovación - CIBAIN, Fundación Universitaria Internacional del Trópico Americano– Unitrópico, Yopal, Casanare (Colombia); Martínez-Pieschacón, D.J. [Departamento de Ciencias Básicas, Universidad Santo Tomás, Tunja, Boyaca (Colombia); Baquero, R. [Departamento de Física, CINVESTAV-IPN, Av. IPN 2508, 07360, México (Mexico)

2017-04-15

Highlights: • We present for the first time the effects of Pb doping on structural and electronic properties of Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Bi2223) using GGA, compared with LDA results. • We found the Pb concentration for which the Bi–O pockets disappear from the Fermi Surface in the Bi2223 compound using GGA and LDA, respectively. - Abstract: We use Density Functional Theory to study the effects on the crystal structure and the electronic band structure of substituting Pb for Bi in Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}. We further use the Local Density Approximation (LDA) and the Generalized Gradient Approximation (GGA). The Virtual Crystal Approximation (VCA) was used to account for the substitution. We found that GGA reproduces better the lattice parameters although in both cases the internal coordinates were reproduced with some uncertainties. We further looked at the behavior of the so called Bi–O pockets, some electronic states that originate on the Bi–O planes and that appear on the Fermi surface (FS) in contradiction to the experimental evidence. We found that LDA and GGA differ on that subject. With 26% Pb and using LDA, the Bi–O pockets run away from the FS. But when GGA is used, it is needed up to 35% Pb to make the Bi–O pockets disappear from the FS. In the last case, once the Bi–O pockets are removed from the FS, we get a very good agreement with angular resolved photo-emission (ARPES) and nuclear magnetic resonance (NMR) experiments.

Films of brookite TiO{sub 2} nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO{sub 2} gas-sensing layers

Energy Technology Data Exchange (ETDEWEB)

Caricato, A.P.; Cesaria, M.; Luches, A.; Martino, M. [University of Salento, Department of Physics, Lecce (Italy); Buonsanti, R. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); Catalano, M.; Manera, M.G.; Taurino, A.; Rella, R. [IMM-CNR, Institute for Microelectronics and Microsystems, Lecce (Italy); Cozzoli, P.D. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); University of Salento, Department of Innovation Engineering, Lecce (Italy)

2011-09-15

Titanium dioxide (TiO{sub 2}) nanorods in the brookite phase, with average dimensions of 3-4 nm x 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO{sub 2}) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm{sup 2} and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of {proportional_to}150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO{sub 2} nanorods and crystalline spherical nanoparticles with an average diameter of {proportional_to}13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO{sub 2} mixed in dry air were obtained. (orig.)

Narrowband pulse-enhanced upconversion of chirped broadband pulses

International Nuclear Information System (INIS)

Zhao, Kun; Yuan, Peng; Zhong, Haizhe; Zhang, Dongfang; Zhu, Heyuan; Qian, Liejia; Chen, Liezun; Wen, Shuangchun

2010-01-01

We propose and demonstrate an efficient sum-frequency mixing scheme based on narrowband and chirped broadband pulses. It combines the advantages of wider spectral acceptance bandwidth and of alleviating the temporal walk-off, which are both beneficial to higher conversion efficiency. Chirped sum-frequency pulses at 455 nm with energy up to 360 µJ, corresponding to a conversion efficiency of ∼ 40%, are obtained and the pulses can be compressed to ∼ 110 fs. The sum-frequency mixing scheme may provide a promising route to the efficient generation of deep-ultraviolet femtosecond pulses

InterProScan Result: FS787904 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS787904 FS787904_5_ORF1 F46B8A7F4DCFA20B SUPERFAMILY SSF55194 Ribosome recycling f...actor, RRF 4.1e-24 T IPR002661 Ribosome recycling factor Biological Process: translation (GO:0006412) ...

Irradiation of amorphous Ta{sub 42}Si{sub 13}N{sub 45} film with a femtosecond laser pulse

Energy Technology Data Exchange (ETDEWEB)

Romano, V. [University of Bern, Institute of Applied Physics, Bern (Switzerland); Bern University of Applied Sciences, Bern (Switzerland); Meier, M. [University of Bern, Institute of Applied Physics, Bern (Switzerland); Theodore, N.D. [Freescale Semiconductor Inc., Tempe, AZ (United States); Marble, D.K. [Tarleton State University, Stephenville, TX (United States); Nicolet, M.A. [California Institute of Technology, Pasadena, CA (United States)

2011-07-15

Films of 260 nm thickness, with atomic composition Ta{sub 42}Si{sub 13}N{sub 45}, on 4'' silicon wafers, have been irradiated in air with single laser pulses of 200 femtoseconds duration and 800 nm wave length. As sputter-deposited, the films are structurally amorphous. A laterally truncated Gaussian beam with a near-uniform fluence of {proportional_to}0.6 J/cm{sup 2} incident normally on such a film ablates 23 nm of the film. Cross-sectional transmission electron micrographs show that the surface of the remaining film is smooth and flat on a long-range scale, but contains densely distributed sharp nanoprotrusions that sometimes surpass the height of the original surface. Dark field micrographs of the remaining material show no nanograins. Neither does glancing angle X-ray diffraction with a beam illuminating many diffraction spots. By all evidence, the remaining film remains amorphous after the pulsed femtosecond irradiation. The same single pulse, but with an enhanced and slightly peaked fluence profile, creates a spot with flat peripheral terraces whose lateral extents shrink with depth, as scanning electron and atomic force micrographs revealed. Comparison of the various figures suggests that the sharp nanoprotrusions result from an ejection of material by brittle fraction and spallation, not from ablation by direct beam-solid interaction. Conditions under which spallation should dominate over ablation are discussed. (orig.)

Growth parameter enhancement for MoS{sub 2} thin films synthesized by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Serna, Martha I.; Higgins, Marissa; Quevedo-Lopez, Manuel A. [Materials Science and Engineering Department, The University of Texas at Dallas, 800 W Campbell Road RL 10, Richardson TX 75080 (United States); Moreno, Salvador [Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080 (United States); Choi, Hyunjoo [Department of Advanced Materials Engineering, Kookmin University, Jeongneung-dong Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Minary-Jolandan, Majid [Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080 (United States); Alan MacDiarmid Nanotech Institute, The University of Texas at Dallas, 800 W Campbell Road RL 10, Richardson TX 75080 (United States)

2016-12-15

Two-dimensional materials such as graphene and MoS{sub 2} have been the main focus of intense research efforts over the past few years. The most common method of exfoliating these materials, although efficient for lab-scale experiments, is not acceptable for large area and practical applications. Here, we report the deposition of MoS{sub 2} layered films on amorphous (SiO{sub 2}) and crystalline substrates (sapphire) using a pulsed laser deposition (PLD) method. Increased substrate temperature (∝700 C) and laser energy density (>530 mJ /cm{sup 2}) promotes crystalline MoS{sub 2} films < 20 nm, as demonstrated by fast Fourier transform (FFT) and transmission electron microscopy (TEM). The method reported here opens the possibility for large area layered MoS{sub 2} films by using a laser ablation processes. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Absorption of femtosecond laser pulses by atomic clusters

International Nuclear Information System (INIS)

Lin Jingquan; Zhang Jie; Li Yingjun; Chen Liming; Lu Tiezheng; Teng Hao

2001-01-01

Energy absorption by Xe, Ar, He atomic clusters are investigated using laser pulses with 5 mJ energy in 150 fs duration. Experimental results show that the size of cluster and laser absorption efficiency are strongly dependent on several factors, such as the working pressure of pulse valve, atomic number Z of the gas. Absorption fraction of Xe clusters is as high as 45% at a laser intensity of 1 x 10 15 W/cm 2 with 20 x 10 5 Pa gas jet backing pressure. Absorption of the atomic clusters is greatly reduced by introducing pre-pulses. Ion energy measurements confirm that the efficient energy deposition results in a plasma with very high ion temperature

Studies on perovskite film ablation and scribing with ns-, ps- and fs-laser pulses

Science.gov (United States)

Bayer, Lukas; Ye, Xinyuan; Lorenz, Pierre; Zimmer, Klaus

2017-10-01

Hybrid organic-inorganic perovskites attract much attention due to their exceptional optoelectronic properties, in particular for photovoltaic (PV) applications. The accurate, high-speed and reliable patterning of the PV films is required for perovskite solar modules fabrication. Laser scribing provides these characteristics needed for industrial fabrication processes. In this work, the laser ablation and scribing of perovskite layers (CH3NH3PbI3: MAPbI3) with different laser sources (ns-, ps-, fs-laser pulses with wavelengths of 248 nm to 2.5 µm) were systematically investigated. The perovskite material was irradiated from both the film side and the substrate (rear side) side to study and compare the particular processes. The patterning results of the perovskite film can be classified into (1) regular laser ablation, (2) thin-film delamination lift-off process, and (3) lift-off with thermal modifications. A particular process, the localised lift-off of single grains from the perovskite film, has been observed and is discussed in relation to the thin-film lift-off process. Ablation and ablation-related mechanisms provide good conditions for laser scribing of the perovskite layer required for module interconnection via P2.

EST Table: FS806480 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS806480 E_FL_fmgV_20N06_F_0 10/09/28 57 %/259 aa ref|XP_001659582.1| xaa-pro dipeptidase pepd/pepq(e.coli...) [Aedes aegypti] gb|EAT39285.1| xaa-pro dipeptidase pepd/pepq(e.coli) [Aedes aegypti... aa gi|189233738|ref|XP_971576.2| PREDICTED: similar to xaa-pro dipeptidase pepd/pepq(e.coli) [Tribolium castaneum] FS768084 fmgV ...

Time resolved studies of H{sub 2}{sup +} dissociation with phase-stabilized laser pulses

Energy Technology Data Exchange (ETDEWEB)

Fischer, Bettina

2010-06-23

In the course of this thesis, experimental studies on the dissociation of H{sub 2}{sup +}(H{sub 2}{sup +}{yields}p+H) in ultrashort laser pulses with a stabilized carrier-envelope phase (CEP) were carried out. In single-pulse measurements, the ability to control the emission direction of low energetic protons, i.e. the localization of the bound electron at one of the nuclei after dissociation, by the CEP was demonstrated. The coincident detection of the emitted protons and electrons and the measurement of their three-dimensional momentum vectors with a reaction microscope allowed to clarify the localization mechanism. Further control was achieved by a pump-control scheme with two timedelayed CEP-stabilized laser pulses. Here the neutral H{sub 2} molecule was ionized in the first pulse and dissociation was induced by the second pulse. Electron localization was shown to depend on the properties of the bound nuclear wave packet in H{sub 2}{sup +} at the time the control pulse is applied, demonstrating the ability to use the shape and dynamics of the nuclear wave packet as control parameters. Wave packet simulations were performed reproducing qualitatively the experimental results of the single and the two-pulse measurements. For both control schemes, intuitive models are presented, which qualitatively explain the main features of the obtained results. (orig.)

InterProScan Result: FS860732 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS860732 FS860732_6_ORF1 0375CFA2D74CE0C2 PRINTS PR01186 INTEGRINB 3.7e-20 T IPR015812 Integri...0)|Biological Process: integrin-mediated signaling pathway (GO:0007229)|Cellular Component: integrin complex (GO:0008305) ...

Effects of pulse duration on magnetostimulation thresholds

Energy Technology Data Exchange (ETDEWEB)

Saritas, Emine U., E-mail: saritas@ee.bilkent.edu.tr [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of Electrical and Electronics Engineering, Bilkent University, Bilkent, Ankara 06800 (Turkey); National Magnetic Resonance Research Center (UMRAM), Bilkent University, Bilkent, Ankara 06800 (Turkey); Goodwill, Patrick W. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Conolly, Steven M. [Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720-1762 (United States); Department of EECS, University of California, Berkeley, California 94720-1762 (United States)

2015-06-15

. Results: The magnetostimulation limits decreased with increasing pulse duration (T{sub pulse}). For T{sub pulse} < 18 ms, the thresholds were significantly higher than at the longest pulse durations (p < 0.01, paired Wilcoxon signed-rank test). The normalized magnetostimulation threshold (B{sub Norm}) vs duration curve at all three frequencies agreed almost identically, indicating that the observed effect is independent of the operating frequency. At the shortest pulse duration (T{sub pulse} ≈ 2 ms), the thresholds were approximately 24% higher than at the asymptotes. The thresholds decreased to within 4% of their asymptotic values for T{sub pulse} > 20 ms. These trends were well characterized (R{sup 2} = 0.78) by a stretched exponential function given by B{sub Norm}=1+αe{sup −(T{sub p}{sub u}{sub l}{sub s}{sub e}/β){sup γ}}, where the fitted parameters were α = 0.44, β = 4.32, and γ = 0.60. Conclusions: This work shows for the first time that the magnetostimulation thresholds decrease with increasing pulse duration, and that this effect is independent of the operating frequency. Normalized threshold vs duration trends are almost identical for a 20-fold range of frequencies: the thresholds are significantly higher at short pulse durations and settle to within 4% of their asymptotic values for durations longer than 20 ms. These results emphasize the importance of matching the human-subject experiments to the imaging conditions of a particular setup. Knowing the dependence of the safety limits to all contributing factors is critical for increasing the time-efficiency of imaging systems that utilize time-varying magnetic fields.

High incidence of rainbow glare after femtosecond laser assisted-LASIK using the upgraded FS200 femtosecond laser.

Science.gov (United States)

Zhang, Yu; Chen, Yue-Guo

2018-03-05

To compare the incidence of rainbow glare (RG) after femtosecond laser assisted-LASIK (FS-LASIK) using the upgraded FS200 femtosecond laser with different flap cut parameter settings. A consecutive series of 129 patients (255 eyes) who underwent FS-LASIK for correcting myopia and/or astigmatism using upgraded WaveLight FS200 femtosecond laser with the original settings was included in group A. Another consecutive series of 129 patients (255 eyes) who underwent FS-LASIK using upgraded WaveLight FS200 femtosecond laser with flap cut parameter settings changed (decreased pulse energy, spot and line separation) was included in group B. The incidence and fading time of RG, confocal microscopic image and postoperative clinical results were compared between the two groups. There were no differences between the two groups in age, baseline refraction, excimer laser ablation depth, postoperative uncorrected visual acuity and refraction. The incidence rate of RG in group A (35/255, 13.73%) was significantly higher than that in group B (4/255, 1.57%) (P  0.05).The confocal microscopic images showed wider laser spot spacing in group A than group B. The incidence of RG was significantly correlated with age and grouping (P laser with original flap cut parameter settings could increase the incidence of RG. The narrower grating size and lower pulse energy could ameliorate this side effect.

Structural relaxation and embrittlement of Cu/sub 59/Zr/sub 41/ and Fe/sub 80/B/sub 20/ glasses

International Nuclear Information System (INIS)

Deng, D.; Argon, A.S.

1986-01-01

The effect of physical aging at 0.92 T/sub c/, on phase separation, crystallization, distributed shear relaxations, hardness, and strain to fracture was investigated in Cu/sub 59/Zr/sub 41/ and Fe/sub 80/B/sub 20/ glasses. In Cu/sub 59/Zr/sub 41/ glass, aging resulted in phase separation prior to crystallization, rather than the expected polymorphous crystallization. In Fe/sub 80/B/sub 20/ in the as-quenched alloys a prominent second-order Curie transition was found at 613K, which was recovered by aging. Apart from a nearly four-fold acceleration of the aging process in Fe/sub 80/B/sub 20/ over the Cu/sub 59/Zr/sub 41/ alloy, their mechanical responses to the aging were very similar in alterations of the internal friction spectrum, evolution of hardness, and strain to fracture

FS laser processing of bio-polymer thin films for studying cell-to-substrate specific response

Energy Technology Data Exchange (ETDEWEB)

Daskalova, A., E-mail: a_daskalova@code.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria); Nathala, Chandra S.R. [Institute of General Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10/134, A-1040 Wien (Austria); Spectra-Physics Vienna, Fernkorngasse 10, 1100 Wien (Austria); Kavatzikidou, P.; Ranella, A. [Institute for Electronic Structure and Lasers-FORTH, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece); Szoszkiewicz, R. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Woloska Str., 02-507 Warsaw, Poland (Poland); Husinsky, W. [Institute of General Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10/134, A-1040 Wien (Austria); Fotakis, C. [Institute for Electronic Structure and Lasers-FORTH, P.O. Box 1385, Vassilika Vouton, 711 10 Heraklion, Crete (Greece)

2016-09-30

Highlights: • Systematic research in the field of fs laser interaction with biopolymers for application in tissue engineering. • Utilizing a new biopolymer blend of collagen/elastin material for studying the interaction process in the fs domain. • Obtaining of improved, circularly shaped, interconnected nanopores, with high reproducibility from collagen/elastin layer. • Observation of randomly arranged pattern outside modification zone due to formation of an impact wave over biofilm surface. • NIH/3T3 cell-interface interaction reveal a preferable cell migration on fs laser-modified surface array. - Abstract: The use of ultra-short pulses for nanoengineering of biomaterials opens up possibilities for biological, medical and tissue engineering applications. Structuring the surface of a biomaterial into arrays with micro- and nanoscale features and architectures, defines new roadmaps to innovative engineering of materials. Thin films of novel collagen/elastin composite and gelatin were irradiated by Ti:sapphire fs laser in air at central wavelength 800 nm, with pulse durations in the range of 30 fs. The size and shape as well as morphological forms occurring in the resulted areas of interaction were analyzed as a function of irradiation fluence and number of pulses by atomic force microscopy (AFM). The fs interaction regime allows generation of well defined micro porous surface arrays. In this study we examined a novel composite consisting of collagen and elastin in order to create a biodegradable matrix to serve as a biomimetic surface for cell attachment. Confocal microscopy images of modified zones reveal formation of surface fringe patterns with orientation direction alongside the area of interaction. Outside the crater rim a wave-like topography pattern is observed. Structured, on a nanometer scale, surface array is employed for cell-culture experiments for testing cell’s responses to substrate morphology. Mice fibroblasts migration was monitored

FS laser processing of bio-polymer thin films for studying cell-to-substrate specific response

International Nuclear Information System (INIS)

Daskalova, A.; Nathala, Chandra S.R.; Kavatzikidou, P.; Ranella, A.; Szoszkiewicz, R.; Husinsky, W.; Fotakis, C.

2016-01-01

Highlights: • Systematic research in the field of fs laser interaction with biopolymers for application in tissue engineering. • Utilizing a new biopolymer blend of collagen/elastin material for studying the interaction process in the fs domain. • Obtaining of improved, circularly shaped, interconnected nanopores, with high reproducibility from collagen/elastin layer. • Observation of randomly arranged pattern outside modification zone due to formation of an impact wave over biofilm surface. • NIH/3T3 cell-interface interaction reveal a preferable cell migration on fs laser-modified surface array. - Abstract: The use of ultra-short pulses for nanoengineering of biomaterials opens up possibilities for biological, medical and tissue engineering applications. Structuring the surface of a biomaterial into arrays with micro- and nanoscale features and architectures, defines new roadmaps to innovative engineering of materials. Thin films of novel collagen/elastin composite and gelatin were irradiated by Ti:sapphire fs laser in air at central wavelength 800 nm, with pulse durations in the range of 30 fs. The size and shape as well as morphological forms occurring in the resulted areas of interaction were analyzed as a function of irradiation fluence and number of pulses by atomic force microscopy (AFM). The fs interaction regime allows generation of well defined micro porous surface arrays. In this study we examined a novel composite consisting of collagen and elastin in order to create a biodegradable matrix to serve as a biomimetic surface for cell attachment. Confocal microscopy images of modified zones reveal formation of surface fringe patterns with orientation direction alongside the area of interaction. Outside the crater rim a wave-like topography pattern is observed. Structured, on a nanometer scale, surface array is employed for cell-culture experiments for testing cell’s responses to substrate morphology. Mice fibroblasts migration was monitored

Generation of a single-cycle optical pulse

International Nuclear Information System (INIS)

Shverdin, M.Y.; Walker, D.R.; Yavuz, D.D.; Yin, G.Y.; Harris, S.E.

2005-01-01

We make use of coherent control of four-wave mixing to the ultraviolet as a diagnostic and describe the generation of a periodic optical waveform where the spectrum is sufficiently broad that the envelope is approximately a single-cycle in length, and where the temporal shape of this envelope may be synthesized by varying the coefficients of a Fourier series. Specifically, using seven sidebands, we report the generation of a train of single-cycle optical pulses with a pulse width of 1.6 fs, a pulse separation of 11 fs, and a peak power of 1 MW

Ultrafast pulse amplification in mode-locked vertical external-cavity surface-emitting lasers

Energy Technology Data Exchange (ETDEWEB)

Böttge, C. N., E-mail: boettge@optics.arizona.edu; Hader, J.; Kilen, I.; Moloney, J. V. [College of Optical Sciences, The University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721 (United States); Koch, S. W. [College of Optical Sciences, The University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721 (United States); Department of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, 35032 Marburg (Germany)

2014-12-29

A fully microscopic many-body Maxwell–semiconductor Bloch model is used to investigate the influence of the non-equilibrium carrier dynamics on the short-pulse amplification in mode-locked semiconductor microlaser systems. The numerical solution of the coupled equations allows for a self-consistent investigation of the light–matter coupling dynamics, the carrier kinetics in the saturable absorber and the multiple-quantum-well gain medium, as well as the modification of the light field through the pulse-induced optical polarization. The influence of the pulse-induced non-equilibrium modifications of the carrier distributions in the gain medium and the saturable absorber on the single-pulse amplification in the laser cavity is identified. It is shown that for the same structure, quantum wells, and gain bandwidth the non-equilibrium carrier dynamics lead to two preferred operation regimes: one with pulses in the (sub-)100 fs-regime and one with multi-picosecond pulses. The recovery time of the saturable absorber determines in which regime the device operates.

Evolution of metastable state molecules N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) in a nanosecond pulsed discharge: A particle-in-cell/Monte Carlo collisions simulation

Energy Technology Data Exchange (ETDEWEB)

Gao Liang; Sun Jizhong; Feng Chunlei; Bai Jing; Ding Hongbin [School of Physics and Optical Electronic Technology, Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams, Chinese Ministry of Education, Dalian University of Technology, Dalian 116024 (China)

2012-01-15

A particle-in-cell plus Monte Carlo collisions method has been employed to investigate the nitrogen discharge driven by a nanosecond pulse power source. To assess whether the production of the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) can be efficiently enhanced in a nanosecond pulsed discharge, the evolutions of metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density and electron energy distribution function have been examined in detail. The simulation results indicate that the ultra short pulse can modulate the electron energy effectively: during the early pulse-on time, high energy electrons give rise to quick electron avalanche and rapid growth of the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density. It is estimated that for a single pulse with amplitude of -9 kV and pulse width 30 ns, the metastable state N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density can achieve a value in the order of 10{sup 9} cm{sup -3}. The N{sub 2}(A{sup 3}{Sigma}{sub u}{sup +}) density at such a value could be easily detected by laser-based experimental methods.

High pulse energy sub-nanosecond Tm-doped fiber laser

Science.gov (United States)

Cserteg, Andras; Guillemet, Sebastien; Hernandez, Yves; Giannone, Domenico

2012-02-01

We report a core pumped thulium-doped fiber amplifier that generates 1.4 μJ pulses at 1980 nm with a repetition rate of 3.6 MHz preserving the original spectral bandwidth of the oscillator. The amplifier chain is seeded by a passively modelocked fiber laser with 5 mW output power and the pulses are stretched to 800 picoseconds. The amplifier is core pumped by a single mode erbium fiber laser. The slope efficiency is 35%. To the best of our knowledge, this is the first demonstration of sub nanosecond pulses with energies higher than 1 μJ coming out of a thulium-doped fiber amplifier.

Graphene-gold supercapacitor as a voltage controlled saturable absorber for femtosecond pulse generation.

Science.gov (United States)

Baylam, Isinsu; Balci, Osman; Kakenov, Nurbek; Kocabas, Coskun; Sennaroglu, Alphan

2016-03-01

We report, for the first time to the best of our knowledge, use of a graphene-gold supercapacitor as a voltage controlled fast saturable absorber for femtosecond pulse generation. The unique design involving only one graphene electrode lowers the insertion loss of the device, in comparison with capacitor designs with two graphene electrodes. Furthermore, use of the high-dielectric electrolyte allows reversible, adjustable control of the absorption level up to the visible region with low bias voltages of only a few volts (0-2 V). The fast saturable absorber action of the graphene-gold supercapacitor was demonstrated inside a multipass-cavity Cr:forsterite laser to generate nearly transform-limited, sub-100 fs pulses at a pulse repetition rate of 4.51 MHz at 1.24 μm.

Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast

Directory of Open Access Journals (Sweden)

Marco Hornung

2015-12-01

Full Text Available We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a pulse duration of 120 fs. On the basis of initially ultra-high contrast seed pulses we expect a temporal intensity contrast better 10 17 200 ps before the peak of the main pulse. We analyzed the temporal intensity contrast from milliseconds to femtoseconds with a dynamic range covering more than 20 orders of magnitude. The pulses were focussed with a f/2-focussing parabola resulting in a peak intensity exceeding 10 20 W / cm 2 . The peak power and intensity are to the best of our knowledge the highest values for 515 nm-laser-pulses achieved so far.

Investigation of the structural, optical and dielectric properties of highly (1 0 0)-oriented (Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20})TiO{sub 3} thin films on LaNiO{sub 3} bottom electrode

Energy Technology Data Exchange (ETDEWEB)

Pontes, D.S.L. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Pontes, F.M., E-mail: fenelon@fc.unesp.br [Department of Chemistry, Universidade Estadual Paulista, P.O. Box 473, 17033-360 Bauru, São Paulo (Brazil); Chiquito, A.J. [NanO LaB, Transporte Eletrônico em Nanoestruturas, Department of Physics, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Longo, E. [Laboratorio Interdisciplinar de Eletroquimica e Cerâmica, Department of Chemistry, Universidade Federal de São Carlos, Via Washington Luiz, Km 235, P.O. Box 676, 13565-905 São Carlos, São Paulo (Brazil); Institute of Chemistry, Universidade Estadual Paulista, Araraquara, São Paulo (Brazil)

2014-07-01

Highlights: • Highly (h 0 0) oriented LNO and PCST thin films were grown on LAO(1 0 0) substrate. • PCST/LNO/LAO structure shown classic ferroelectric–paraelectric phase transition. • PCST/LNO/LAO structure shows superior dielectric properties. • PCST/LAO films showed a direct allowed optical transition. - Abstract: Highly (1 0 0)-oriented Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure was fabricated using a chemical deposition process via spin-coating technique. XRD revealed that both LNO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films grown on LAO(1 0 0) substrate and LNO/LAO(1 0 0) structure were crystallized to be highly (h 0 0)-oriented, respectively. AFM images revealed smooth surfaces, spherical-shaped grains and a crack-free surface with a roughness of about 3–7 nm. The tetragonal perovskite phase was confirmed by Raman spectroscopy for Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO and Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LAO structures. The optical transmittance of 340 nm thick Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3} films on a LAO(1 0 0) substrate exhibited an average transmittance above 80% in the wavelength range of 500–1000 nm and an optical band gap E{sub g} of 3.56 and 2.87 eV for the direct and indirect transition processes, respectively. The Au/Pb{sub 0.60}Ca{sub 0.20}Sr{sub 0.20}TiO{sub 3}/LNO/LAO structure has a hysteresis loop with remnant polarization, P{sub r}, of 12 μC/cm{sup 2}, and a coercive field, E{sub c}, of 46 kV/cm for an electric field at 370 kV/cm along with a dielectric constant over 1200.

Pulsed laser ablation and deposition of niobium carbide

International Nuclear Information System (INIS)

Sansone, M.; De Bonis, A.; Santagata, A.; Rau, J.V.; Galasso, A.; Teghil, R.

2016-01-01

Highlights: • We have deposited in vacuum niobium carbide films by fs and ns PLD. • We have compared PLD performed by ultra-short and short laser pulses. • The films deposited by fs PLD of NbC are formed by nanoparticles. • The structure of the films produced by fs PLD at 500 °C corresponds to NbC. - Abstract: NbC crystalline films have been deposited in vacuum by ultra-short pulsed laser deposition technique. The films have been characterized by transmission and scanning electron microscopies and by X-ray diffraction. To clarify the ablation–deposition mechanism, the plasma produced by the ablation process has been characterized by optical emission spectroscopy and fast imaging. A comparison of the results with those obtained by ns pulsed deposition of the same target has been carried out.

Suprathermal Electron Generation and Channel Formation by an Ultrarelativistic Laser Pulse in an Underdense Preformed Plasma

International Nuclear Information System (INIS)

Malka, G.; Gaillard, R.; Miquel, J.L.; Rousseaux, C.; Bonnaud, G.; Busquet, M.; Lours, L.; Fuchs, J.; Pepin, H.; Fuchs, J.; Amiranoff, F.; Baton, S.D.

1997-01-01

Relativistic electrons are produced, with energies up to 20MeV, by the interaction of a high-intensity subpicosecond laser pulse (1 μm , 300 fs , 10 19 W/cm 2 ) with an underdense plasma. Two suprathermal electron populations appear with temperatures of 1 and 3MeV. In the same conditions, the laser beam transmission is increased up to 20% 30%. We observe both features along with the evidence of laser pulse channeling. A fluid model predicts a strong self-focusing of the pulse. Acceleration in the enhanced laser field seems the most likely mechanism leading to the second electron population. copyright 1997 The American Physical Society

Low operating voltage InGaZnO thin-film transistors based on Al{sub 2}O{sub 3} high-k dielectrics fabricated using pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Geng, G. Z.; Liu, G. X.; Zhang, Q.; Shan, F. K. [Qingdao University, Qingdao (China); DongEui University, Busan (Korea, Republic of); Lee, W. J.; Shin, B. C. [DongEui University, Busan (Korea, Republic of); Cho, C. R. [Pusan National University, Busan (Korea, Republic of)

2014-05-15

Low-voltage-driven amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) with an Al{sub 2}O{sub 3} dielectric were fabricated on a Si substrate by using pulsed laser deposition. Both Al{sub 2}O{sub 3} and IGZO thin films are amorphous, and the thin films have very smooth surfaces. The Al{sub 2}O{sub 3} gate dielectric exhibits a very low leakage current density of 1.3 x 10{sup -8} A/cm{sup 2} at 5 V and a high capacitance density of 60.9 nF/cm{sup 2}. The IGZO TFT with a structure of Ni/IGZO/Al{sub 2}O{sub 3}/Si exhibits high performance with a low threshold voltage of 1.18 V, a high field effect mobility of 20.25 cm{sup 2}V{sup -1}s{sup -1}, an ultra small subthreshold swing of 87 mV/decade, and a high on/off current ratio of 3 x 10{sup 7}.

First-principles prediction of optical second-order harmonic generation in the endohedral N-C{sub 60} compound

Energy Technology Data Exchange (ETDEWEB)

Zhang, G. P.; Strubbe, David A.; Louie, Steven G.; George, Thomas F. [Department of Physics, Indiana State University, Terre Haute, Indiana 47809 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States) and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Chemistry and Biochemistry and Department of Physics and Astronomy, Office of the Chancellor and Center for Nanoscience, University of Missouri-St. Louis, St. Louis, Missouri 63121 (United States)

2011-08-15

Non-linear-optical properties in C{sub 60} have attracted enormous attention for over two decades. The endohedral complex N-C{sub 60}, with its remarkable thermal stability and spin-quartet ground state, is a candidate for future room-temperature quantum computing, but there has been no investigation of its non-linear-optical properties. Here, a first-principles calculation shows that N-C{sub 60} is a promising material for nanoscale and ultrafast modulations. Excitation by a pump laser pulse of the nitrogen-atom vibration inside the C{sub 60} cage transiently breaks inversion symmetry and can enable second-harmonic generation (SHG) from a probe pulse. Unlike the SHG observed in C{sub 60} thin films, this harmonic signal is switched on and off periodically every 345 fs. For an fcc crystal of N-C{sub 60}, the second-order susceptibility {chi}{sup (2)} is on the order of 10{sup -8} esu, similar to commercially used nonlinear materials.

Efficient terahertz wave generation from GaP crystals pumped by chirp-controlled pulses from femtosecond photonic crystal fiber amplifier

International Nuclear Information System (INIS)

Li, Jiang; Shi, Junkai; Xu, Baozhong; Xing, Qirong; Wang, Chingyue; Chai, Lu; Liu, Bowen; Hu, Minglie; Li, Yanfeng; Fedotov, Andrey B.; Zheltikov, Aleksei M.

2014-01-01

A chirp-tunable femtosecond 10 W, 42 MHz photonic-crystal-fiber oscillator-amplifier system that is capable of delivering sub-60 fs light pulses at 1040 nm is used to demonstrate high-efficiency terahertz radiation generation via optical rectification in GaP crystals only a few millimeters in length. The optimization of the chirp of the fiber-laser pulses is shown to radically enhance the terahertz output, indicating one possible way to more efficiently use these extended nonlinear crystals in compact fiber-pumped terahertz radiation sources

Comparison of SeaWiFS and MODIS time series of inherent optical properties for the Adriatic Sea

Directory of Open Access Journals (Sweden)

F. Mélin

2011-05-01

Full Text Available Time series of inherent optical properties (IOPs derived from SeaWiFS and MODIS are compared for the Adriatic Sea. The IOPs are outputs of the Quasi-Analytical Algorithm and include total absorption a, phytoplankton absorption a<sub>ph>, absorption associated with colored detrital material (CDM a<sub>cdm>, and particle backscattering coefficient b<sub>bp>. The average root-mean square difference Δ computed for log-transformed distributions decreases for $a$ from 0.084 at 412 nm to 0.052 at 490 nm, is higher for a<sub>ph>(443 (0.149 than for a<sub>cdm>(443 (0.071, and is approximately 0.165 for b<sub>bp> at various wavelengths. The SeaWiFS a at 443 and 490 nm, a<sub>ph> at 443 nm and b<sub>bp> are on average higher than the MODIS counterparts. Statistics show significant variations in space and time. There is an overall increasing gradient for Δ associated with the absorption terms from the open southern and central Adriatic to the northwest part of the basin, and a reversed gradient for the particulate backscattering coefficient. For time series analysis, only a(412 and a<sub>cdm>(443 currently present an unbiased continuity bridging the SeaWiFS and MODIS periods for the Adriatic Sea.

Ultrashort-pulse measurement using noninstantaneous nonlinearities: Raman effects in frequency-resolved optical gating

International Nuclear Information System (INIS)

DeLong, K.W.; Ladera, C.L.; Trebino, R.; Kohler, B.; Wilson, K.R.

1995-01-01

Ultrashort-pulse-characterization techniques generally require instantaneously responding media. We show that this is not the case for frequency-resolved optical gating (FROG). We include, as an example, the noninstantaneous Raman response of fused silica, which can cause errors in the retrieved pulse width of as much as 8% for a 25-fs pulse in polarization-gate FROG. We present a modified pulse-retrieval algorithm that deconvolves such slow effects and use it to retrieve pulses of any width. In experiments with 45-fs pulses this algorithm achieved better convergence and yielded a shorter pulse than previous FROG algorithms

High-energy few-cycle pulse compression through self-channeling in gases

International Nuclear Information System (INIS)

Hauri, C.; Merano, M.; Trisorio, A.; Canova, F.; Canova, L.; Lopez-Martens, R.; Ruchon, T.; Engquist, A.; Varju, K.; Gustafsson, E.

2006-01-01

Complete test of publication follows. Nonlinear spectral broadening of femtosecond optical pulses by intense propagation in a Kerr medium followed by temporal compression constitutes the Holy Grail for ultrafast science since it allows the generation of intense few-cycle optical transients from longer pulses provided by now commercially available femtosecond lasers. Tremendous progress in high-field and attosecond physics achieved in recent years has triggered the need for efficient pulse compression schemes producing few-cycle pulses beyond the mJ level. We studied a novel pulse compression scheme based on self-channeling in gases, which promises to overcome the energy constraints of hollow-core fiber compression techniques. Fundamentally, self-channeling at high laser powers in gases occurs when the self-focusing effect in the gas is balanced through the dispersion induced by the inhomogeneous refractive index resulting from optically-induced ionization. The high nonlinearity of the ionization process poses great technical challenges when trying to scale this pulse compression scheme to higher energies input energies. Light channels are known to be unstable under small fluctuations of the trapped field that can lead to temporal and spatial beam breakup, usually resulting in the generation of spectrally broad but uncompressible pulses. Here we present experimental results on high-energy pulse compression of self-channeled 40-fs pulses in pressure-gas cells. In the first experiment, performed at the Lund Laser Center in Sweden, we identified a particular self-channeling regime at lower pulse energies (0.8 mJ), in which the ultrashort pulses are generated with negative group delay dispersion (GDD) such that they can be readily compressed down to near 10-fs through simple material dispersion. Pulse compression is efficient (70%) and exhibits exceptional spatial and temporal beam stability. In a second experiment, performed at the LOA-Palaiseau in France, we

Femtosecond and nanosecond pulsed laser deposition of silicon and germanium

Energy Technology Data Exchange (ETDEWEB)

Reenaas, Turid Worren [Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Lee, Yen Sian [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Chowdhury, Fatema Rezwana; Gupta, Manisha; Tsui, Ying Yin [Department of Electrical and Computer Engineering, University of Alberta (Canada); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Ling [Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Kok, Soon Yie [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Shan, E-mail: seongshan@gmail.com [Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2015-11-01

Highlights: • Ge and Si were deposited by fs and ns laser at room temperature and at vacuum. • Ion of 10{sup 4} ms{sup −1} and 30–200 eV was obtained for ns ablation for Ge and Si. • Highly energetic ions of 10{sup 5} ms{sup −1} with 2–7 KeV were produced in fs laser ablation. • Nanocrystalline Si and Ge were deposited by using fs laser. • Nanoparticles < 10 nm haven been obtained by fs laser. - Abstract: 150 fs Ti:Sapphire laser pulsed laser deposition of Si and Ge were compared to a nanosecond KrF laser (25 ns). The ablation thresholds for ns lasers were about 2.5 J cm{sup −2} for Si and 2.1 J cm{sup −2} for Ge. The values were about 5–10 times lower when fs laser were used. The power densities were 10{sup 8}–10{sup 9} W cm{sup −2} for ns but 10{sup 12} W cm{sup −2} for fs. By using an ion probe, the ions emission at different fluence were measured where the emitting ions achieving the velocity in the range of 7–40 km s{sup −1} and kinetic energy in the range of 30–200 eV for ns laser. The ion produced by fs laser was measured to be highly energetic, 90–200 km s{sup −1}, 2–10 KeV. Two ion peaks were detected above specific laser fluence for both ns and fs laser ablation. Under fs laser ablation, the films were dominated by nano-sized crystalline particles, drastically different from nanosecond pulsed laser deposition where amorphous films were obtained. The ions characteristics and effects of pulse length on the properties of the deposited films were discussed.

Mechanical study of 20 MJ superconducting pulse coil

International Nuclear Information System (INIS)

Hattori, Yasuhide; Shimamoto, Susumu

1985-09-01

This paper describes calculation methods and computer codes of stress distribution in a circular-shaped superconducting pulsed coils. The stress problems of a large sized superconducting coil, for example, are discussed for 20 MJ pool-cooled pulse coil. Young's modulus of a stranded flat cable, low rigidity, is measured and evaluated. (author)

Polarization controlled deep sub-wavelength periodic features written by femtosecond laser on nanodiamond thin film surface

Energy Technology Data Exchange (ETDEWEB)

Kumar Kuntumalla, Mohan; Srikanth, Vadali V. S. S., E-mail: vvsssse@uohyd.ernet.in [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Rajamudili, Kuladeep; Rao Desai, Narayana [School of Physics, University of Hyderabad, Hyderabad 500046 (India)

2014-04-21

Deep sub-wavelength (Λ/λ = ∼0.22) periodic features are induced uniformly on a nanodiamond (ND) thin film surface using femtosecond (fs) laser irradiation (pulse duration = ∼110 fs and central wavelength of ∼800 nm). The topography of the surface features is controlled by the laser polarization. Orientation of features is perpendicular to laser polarization. Periodicity (spatial periodicity of < λ/4) of the surface features is less than the laser wavelength. This work gives an experimental proof of polarization controlled surface plasmon-fs laser coupling mechanism prompting the interaction between fs laser and solid matter (here ND thin film) which in turn is resulting in the periodic surface features. Scanning electron microscopy in conjunction with micro Raman scattering, X-ray diffraction, and atomic force microscopy are carried out to extract surface morphology and phase information of the laser irradiated regions. This work demonstrates an easy and efficient surface fabrication technique.

Experimental observation of pulse delay and speed-up in cascaded quantum well gain and absorber media

DEFF Research Database (Denmark)

Hansen, Per Lunnemann; Poel, Mike van der; Yvind, Kresten

2008-01-01

Slow-down and speed-up of 180 fs pulses in semiconductor waveguides beyond the existing models is obseved. Cascaded gain and absorbing sections is shown to provide significant temporal pulse shifting at near constant output pulse energy.......Slow-down and speed-up of 180 fs pulses in semiconductor waveguides beyond the existing models is obseved. Cascaded gain and absorbing sections is shown to provide significant temporal pulse shifting at near constant output pulse energy....

Stable structures for Al{sub 20} clusters

Energy Technology Data Exchange (ETDEWEB)

Yao Changhong [Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)]. E-mail: phych@zju.edu.cn; Song Bin [Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cao Peilin [Department of Physics and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang 310027 (China)

2005-06-20

The low-lying energy structures of Al{sub 20} cluster are obtained by full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO-MD) method. A set of new low-lying energy structures including a new lowest energy structure, were found in our calculation. The waist-capped double icosahedral structure, which was considered as the global minimum previously, is merely one of the low-lying structures. Comparison and discussion between Al{sub 20} and Si{sub 20} have been made.

Thickness dependence of dynamic and static magnetic properties of pulsed laser deposited La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films on SrTiO{sub 3}(001)

Energy Technology Data Exchange (ETDEWEB)

Monsen, Åsmund [Department of Physics, NTNU, 7491 Trondheim (Norway); Boschker, Jos E. [Department of Electronics and Telecommunications, NTNU, 7491 Trondheim (Norway); Macià, Ferran [Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Wells, Justin W. [Department of Physics, NTNU, 7491 Trondheim (Norway); Nordblad, Per [Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Kent, Andrew D. [Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Mathieu, Roland [Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Tybell, Thomas [Department of Electronics and Telecommunications, NTNU, 7491 Trondheim (Norway); Wahlström, Erik, E-mail: erik.wahlstrom@ntnu.no [Department of Physics, NTNU, 7491 Trondheim (Norway)

2014-11-15

We present a comprehensive study of the thickness dependence of static and magneto-dynamic magnetic properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3}. Epitaxial pulsed laser deposited La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/SrTiO{sub 3}(001) thin films in the range from 3 unit cell (uc) to 40 uc (1.2–16 nm) have been investigated through ferromagnetic resonance (FMR) spectroscopy and SQUID magnetometry at variable temperature. Magnetodynamically, three different thickness, d, regimes are identified: 20 uc ≲d uc where the system is bulk like, a transition region 8 uc ≤d≲20 uc where the FMR linewidth and the position depend on thickness and d=6 uc which displays significantly altered magnetodynamic properties, while still displaying bulk magnetization. Magnetization and FMR measurements are consistent with a nonmagnetic volume corresponding to ∼4 uc. We observe a reduction of Curie temperature (T{sub C}) with decreasing thickness, which is coherent with a mean field model description. The reduced ordering temperature also accounts for the thickness dependence of the magnetic anisotropy constants and resonance fields. The damping of the system is strongly thickness dependent, and is for thin films dominated by thickness dependent anisotropies, yielding both a strong two-magnon scattering close to T{sub c} and a low temperature broadening. For the bulk like samples a large part of the broadening can be linked to spread in magnetic anisotropies attributed to crystal imperfections/domain boundaries of the bulk like film. - Highlights: • Thickness dependent magnetodynamic anisotropy constants and line-widths have been measured. • For thicknesses >8nm the films are bulk-like. • Thin film line-widths are dominated by surface/interface imperfections. • Thick film line-widths are dominated by crystal imperfections/domain boundaries.

A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

Science.gov (United States)

Binh, P H; Trong, V D; Renucci, P; Marie, X

2013-08-01

We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

Photodissociation of H{sub 2}{sup +} by intense chirped pulses - beyond the effect of pulse duration and peak power

Energy Technology Data Exchange (ETDEWEB)

Lev, U; Prabhudesai, V; Natan, A; Bruner, B; Diner, A; Heber, O; Strasser, D; Schwalm, D; Silberberg, Y; Zajfman, D [Faculty of Physics, Weizmann Institute of Science, Rehovot 76100 (Israel); Ben-Itzhak, I; Hua, J J; Esry, B D, E-mail: uri.lev@Weizmann.ac.i [Department of Physics, Kansas State University, Manhattan, KS 66506 (United States)

2009-11-01

H{sub 2}{sup +} photodissociation, induced by intense short laser pulses, was measured by a full 3D imaging system. We have conducted a series of experiments, in which we systematically changed the linear chirp, using a pulse shaper, and observed the kinetic energy release spectra(KER). Distinct differences in the KER spectra are observed both in peak positions and angular distribution for laser pulses with similar duration and intensity but opposite chirp sign.

Growth and characterization of polycrystalline Ge{sub 1-x}C{sub x} by reactive pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Hernandez, M.P., E-mail: mayrap@fisica.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Zapata y G, P.O. Box 10400, Universidad de La Habana (Cuba); Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, Baja California (Mexico); Ulloa, L. [Universidad de Guadalajara, (CUCEI) Blvd. Marcelino Garcia Barragan 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Gallegos, J.A.; Yee-Madeiros, H. [Escuela Superior de Fisica y Matematicas-IPN, UP' ALM' , Colonia Lindavista 07738 (Mexico)

2011-03-15

Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T{sub s}, on C incorporation to substitutional sites (x) in Ge{sub 1-x}C{sub x} was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T{sub s} of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T{sub s} from 250 deg. C to 350 deg. C. At T{sub s} = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T{sub s} being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T{sub s} plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

Ultra-short laser processing of transparent material at the interface to liquid

International Nuclear Information System (INIS)

Boehme, R; Pissadakis, S; Ehrhardt, M; Ruthe, D; Zimmer, K

2006-01-01

Similarly to laser-induced backside wet etching (LIBWE) with nanosecond ultraviolet (ns UV) laser pulses, the irradiation of the solid/liquid interface of fused silica with sub-picosecond (sub-ps) UV and femtosecond near infrared (fs NIR) laser pulses results in etching of the fused silica surface and deposition of decomposition products from liquid. Furthermore, the etch threshold is reduced compared with both direct ablation with an fs laser in air and backside etching with UV ns pulses. Using 0.5 M pyrene/toluene as absorbing liquid, the thresholds were determined to be 70 mJ cm -2 (sub-ps UV) and 330 mJ cm -2 (fs NIR). Furthermore, an almost linear increase in the etch rate with increasing laser fluence was found. The roughness of surfaces backside etched with ultra-short pulses is higher in comparison with ns pulses but lower than that obtained using direct fs laser ablation. Hence a combination of processes involved in fs laser ablation and ns backside etching can be expected. The processes at the ultra-short pulse laser irradiated solid/liquid interface are discussed, considering the effects of ultra-fast heating, multi-photon absorption processes, as well as defect generation in the materials

Monolithic stabilized Yb-fiber All-PM laser directly delivering nJ-level femtosecond pulses

DEFF Research Database (Denmark)

Turchinovich, Dmitry; Liu, Xiaomin; Lægsgaard, Jesper

2008-01-01

We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality.......We present a monolithic, self-starting, all-PM, stabilized Yb-fiber laser, pulse-compressed in a hollow-core PM photonic crystal fiber, providing the 370 fs pulses of 4 nJ energy with high mode quality....

Study on Digital Pulse Shape Discrimination System in BF{sub 3} Detector

Energy Technology Data Exchange (ETDEWEB)

Kim, Jinhyeong; Kim, J. H.; Choi, H. D. [Seoul National Univ., Seoul (Korea, Republic of)

2013-10-15

In this study, we develop the digital PSD system and discriminate the background signal of BF{sub 3}. Spectrum shapes are different according to the t{sub start} setting method, and it is favorable to set it as the certain ratio of maximum height. In future, it will be performed to vary t{sub start} point to optimize the pulse discrimination. To quantify the performance, Figure Of Merit (FOM) will be determined. For the nuclear non-proliferation and safeguards, an accurate and reliable measurement of nuclear material is essential. The nuclear material emits neutron and γ-ray, simultaneously. For the accurate detection of the nuclear material, neutron should be discriminated from γ-ray or background radiation. In previous study, N. S. Jung developed pulse shape analysis method based on NIM and CAMAC system. However, applications of other discrimination methods based on different detection modules or changing parameters are time-and-money consuming procedures in analogue systems. Today, the performance of digitizers is improved and it replaces some radiation measurement systems which require simple and portable equipment. Digital Pulse Shape Discrimination (PSD) method by using a digital oscilloscope is developed and applied to a neutron detection system by using BF{sub 3} detector in this study.

Measurement of the B{sub s}{sup 0}-B{sup Macron }{sub s}{sup 0} oscillation frequency {Delta}m{sub s} in B{sub s}{sup 0}{yields}D{sub s}{sup -}(3){pi} decays

Energy Technology Data Exchange (ETDEWEB)

Aaij, R. [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands); Adeva, B. [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Adinolfi, M. [H.H. Wills Physics Laboratory, University of Bristol, Bristol (United Kingdom); Adrover, C. [CPPM, Aix-Marseille Universite, CNRS/IN2P3, Marseille (France); Affolder, A. [Oliver Lodge Laboratory, University of Liverpool, Liverpool (United Kingdom); Ajaltouni, Z. [Clermont Universite, Universite Blaise Pascal, CNRS/IN2P3, LPC, Clermont-Ferrand (France); Albrecht, J.; Alessio, F. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Alexander, M. [School of Physics and Astronomy, University of Glasgow, Glasgow (United Kingdom); Alkhazov, G. [Petersburg Nuclear Physics Institute (PNPI), Gatchina (Russian Federation); Alvarez Cartelle, P. [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Alves, A.A. [Sezione INFN di Roma La Sapienza, Roma (Italy); Amato, S. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro (Brazil); Amhis, Y. [Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland); Anderson, J. [Physik-Institut, Universitaet Zuerich, Zuerich (Switzerland); Appleby, R.B. [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom); Aquines Gutierrez, O. [Max-Planck-Institut fuer Kernphysik (MPIK), Heidelberg (Germany); Archilli, F. [Laboratori Nazionali dell' INFN di Frascati, Frascati (Italy); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Arrabito, L. [CC-IN2P3, CNRS/IN2P3, Lyon-Villeurbanne (France); Artamonov, A. [Institute for High Energy Physics (IHEP), Protvino (Russian Federation); and others

2012-03-19

The B{sub s}{sup 0}-B{sup Macron }{sub s}{sup 0} oscillation frequency {Delta}m{sub s} is measured with 36 pb{sup -1} of data collected in pp collisions at {radical}(s)=7 TeV by the LHCb experiment at the Large Hadron Collider. A total of 1381 B{sub s}{sup 0}{yields}D{sub s}{sup -}{pi}{sup +} and B{sub s}{sup 0}{yields}D{sub s}{sup -}{pi}{sup +}{pi}{sup -}{pi}{sup +} signal decays are reconstructed, with average decay time resolutions of 44 fs and 36 fs, respectively. An oscillation signal with a statistical significance of 4.6{sigma} is observed. The measured oscillation frequency is {Delta}m{sub s}=17.63{+-}0.11(stat){+-}0.02(syst) ps{sup -1}.

Absolute number density and kinetic analysis of CF, CF{sub 2} and C{sub 2}F{sub 4} molecules in pulsed CF{sub 4}/H{sub 2} rf plasmas

Energy Technology Data Exchange (ETDEWEB)

Stepanov, Sergey

2010-04-26

Tunable Diode Laser Absorption Spectroscopy in the mid InfraRed spectral range (IR-TDLAS) has been applied to investigate the behaviour of CF, CF{sub 2} and C{sub 2}F{sub 4} species produced in pulsed CF{sub 4}/H{sub 2} capacitively coupled radio frequency plasmas (13.56 MHz CCP). This experimental technique was shown to be suitable for temporally resolved measurements of the absolute number density of the target molecules in the studied fluorocarbon discharges. The temporal resolution of about 20..40 ms typically achieved in the standard data acquisition mode (''stream mode'') was sufficient for the real-time measurements of CF{sub 2} and C{sub 2}F{sub 4}, but not of CF whose kinetics was observed to be much faster. Therefore, a more sophisticated approach (''burst mode'') providing a temporal resolution of 0.94 ms was established and successfully applied to CF density measurements. In order to enable the TDLAS measurements of the target species, preliminary investigations on their spectroscopic data had been carried out. In particular, pure C{sub 2}F{sub 4} has been produced in laboratory by means of vacuum thermal decomposition (pyrolysis) of polytetrafluoroethylene and used as a reference gas. Therefore, an absorption structure consisting of several overlapping C{sub 2}F{sub 4} lines around 1337.11 cm{sup -1} was selected and carefully calibrated, which provided the first absolute measurements of the species by means of the applied experimental technique. The absolute number density traces measured for CF, CF{sub 2} and C{sub 2}F{sub 4} in the studied pulsed plasmas were then analysed, in which two differential balance equations were proposed for each of the species to describe their behaviour during both ''plasma on'' and ''plasma off'' phases. Analytical solutions of the balance equations were used to fit the experimental data and hence to deduce important information on the

Absolute number density and kinetic analysis of CF, CF{sub 2} and C{sub 2}F{sub 4} molecules in pulsed CF{sub 4}/H{sub 2} rf plasmas

Energy Technology Data Exchange (ETDEWEB)

Stepanov, Sergey

2010-04-26

Tunable Diode Laser Absorption Spectroscopy in the mid InfraRed spectral range (IR-TDLAS) has been applied to investigate the behaviour of CF, CF{sub 2} and C{sub 2}F{sub 4} species produced in pulsed CF{sub 4}/H{sub 2} capacitively coupled radio frequency plasmas (13.56 MHz CCP). This experimental technique was shown to be suitable for temporally resolved measurements of the absolute number density of the target molecules in the studied fluorocarbon discharges. The temporal resolution of about 20..40 ms typically achieved in the standard data acquisition mode (''stream mode'') was sufficient for the real-time measurements of CF{sub 2} and C{sub 2}F{sub 4}, but not of CF whose kinetics was observed to be much faster. Therefore, a more sophisticated approach (''burst mode'') providing a temporal resolution of 0.94 ms was established and successfully applied to CF density measurements. In order to enable the TDLAS measurements of the target species, preliminary investigations on their spectroscopic data had been carried out. In particular, pure C{sub 2}F{sub 4} has been produced in laboratory by means of vacuum thermal decomposition (pyrolysis) of polytetrafluoroethylene and used as a reference gas. Therefore, an absorption structure consisting of several overlapping C{sub 2}F{sub 4} lines around 1337.11 cm{sup -1} was selected and carefully calibrated, which provided the first absolute measurements of the species by means of the applied experimental technique. The absolute number density traces measured for CF, CF{sub 2} and C{sub 2}F{sub 4} in the studied pulsed plasmas were then analysed, in which two differential balance equations were proposed for each of the species to describe their behaviour during both ''plasma on'' and ''plasma off'' phases. Analytical solutions of the balance equations were used to fit the experimental data and hence to deduce important information on the kinetics of the studied molecules. In particular, during the ''plasma off'' phase

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

Energy Technology Data Exchange (ETDEWEB)

Bonse, J., E-mail: joern.bonse@bam.de [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Höhm, S. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S. [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J. [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

2016-06-30

Graphical abstract: - Highlights: • Large areas covered with sub-100 nm LIPSS (HSFL) were manufactured by fs-laser irradiation on titanium surfaces. • Tribological performance of HSFL covered areas was qualified in reciprocal sliding tests in two different lubricating oils. • HSFL on titanium do not endure the tribological tests. • For a beneficial tribological performance, the tribological sample deformation must be smaller than the LIPSS modulation depth. - Abstract: Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

International Nuclear Information System (INIS)

Bonse, J.; Höhm, S.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Rosenfeld, A.; Krüger, J.

2016-01-01

Graphical abstract: - Highlights: • Large areas covered with sub-100 nm LIPSS (HSFL) were manufactured by fs-laser irradiation on titanium surfaces. • Tribological performance of HSFL covered areas was qualified in reciprocal sliding tests in two different lubricating oils. • HSFL on titanium do not endure the tribological tests. • For a beneficial tribological performance, the tribological sample deformation must be smaller than the LIPSS modulation depth. - Abstract: Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

Electronic structure and high thermoelectric properties of a new material Ba{sub 3}Cu{sub 20}Te{sub 13}

Energy Technology Data Exchange (ETDEWEB)

Yang, Gui, E-mail: kuiziyang@126.com [College of Physics and Electrical Engineering, Anyang Normal University, Anyang, Henan, 455000 (China); Wu, Jinghe [Department of Physics and Electronic Engineering, Henan Institute of Education, Zhengzhou, 450046 (China); Zhang, Jing; Ma, Dongwei [College of Physics and Electrical Engineering, Anyang Normal University, Anyang, Henan, 455000 (China)

2016-09-05

The electronic structure and high thermoelectric properties of Ba{sub 3}Cu{sub 20}Te{sub 13} are studied using first principles calculations and the semiclassical Boltzmann theory. The coexistence of ionic and covalent bonding in Ba{sub 3}Cu{sub 20}Te{sub 13} indicates that it is a Zintl phase compound. The calculated band structure shows that the compound is a semiconductor with an indirect band gap ∼0.45 eV, which is an appropriate band for the high thermoelectric performance. The transport calculations based on the electronic structure indicate that it exhibits relatively large Seebeck coefficients, high electrical conductivities, and high power factor. For Ba{sub 3}Cu{sub 20}Te{sub 13}, the n-type doping may achieve a higher thermoelectric performance than that of p-type doping. It is worth noting that the thermoelectric parameters of Ba{sub 3}Cu{sub 20}Te{sub 13} are comparable or larger than that of Ca{sub 5}Al{sub 2}Sb{sub 6}, a typical Zintl compound representative with high thermoelectric performance. - Highlights: • The electronic structure and thermoelectric(TE) properties are firstly studied. • The heavy and light bands near the Fermi level benefit TE properties. • The comparison indicates Ba{sub 3}Cu{sub 20}Te{sub 13} is a potential high TE material.

Optical fiber link for transmission of 1-nJ femtosecond laser pulses at 1550 nm

DEFF Research Database (Denmark)

Eichhorn, Finn; Olsson, Rasmus Kjelsmark; Buron, Jonas Christian Due

2010-01-01

We report on numerical and experimental characterization of the performance of a fiber link optimized for the delivery of sub-100-fs laser pulses at 1550 nm over several meters of fiber. We investigate the power handling capacity of the link, and demonstrate all-fiber delivery of 1-nJ pulses over...... a distance of 5.3 m. The fiber link consists of dispersion-compensating fiber (DCF) and standard single-mode fiber. The optical pulses at different positions in the fiber link are measured using frequency-resolved optical gating (FROG). The results are compared with numerical simulations of the pulse...... propagation based on the generalized nonlinear Schrödinger equation. The high input power capacity of the fiber link allows the splitting and distribution of femtosecond pulses to an array of fibers with applications in multi-channel fiber-coupled terahertz time-domain spectroscopy and imaging systems. We...

Structural and luminescence properties of SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+},Nd{sup 3+} phosphor thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Wako, A.H., E-mail: wakoah@ufs.ac.za [Department of Physics, University of the Free State, QwaQwa Campus, Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, F.B. [Department of Physics, University of the Free State, QwaQwa Campus, Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA-9300 (South Africa)

2016-01-01

Thin films of Eu{sup 2+} doped and Dy{sup 3+},Nd{sup 3+} co-doped Strontium Aluminate (SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+},Nd{sup 3+}) phosphors were grown on Si(100) substrates by a pulsed laser deposition (PLD) technique using a 266 nm Nd:YAG pulsed laser under varying substrate temperature and the working atmosphere during the film deposition process. The effect of substrate temperatures and argon partial pressure on the structure and luminescence properties of the as-deposited SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+},Nd{sup 3+} phosphor thin films were analysed. XRD patterns showed that with increasing substrate temperature and argon partial pressure the peaks in the direction (220) shifted to the lower 2-theta angles. Photoluminescence (PL) data collected in air at room temperature revealed a slight shift in the peak wavelength of the PL spectra observed from the thin films when compared to the PL spectra of the phosphor in powder form, which is probably due to a change in the crystal field. The PL intensity of the samples was highest for 100 °C substrate temperature and 20 mTorr argon partial pressure. Due to this, the effect of argon partial pressure was studied at a constant substrate temperature of 100 °C while the effect of Substrate temperatures recorded at 20 mTorr argon pressure respectively.

Pulse radiolysis study of NaNO/sub 2/ and NaNO/sub 3/ solutions. [Electrons

Energy Technology Data Exchange (ETDEWEB)

Broszkiewicz, R K [Institute of Nuclear Research, Warsaw (Poland)

1976-01-01

The pulse radiolysis of aqueous solutions of NaNO/sub 2/ and NaNO/sub 3/ has been done. In the nitrate solutions the transient species NO/sup 2 -//sub 2/ and NO/sub 2/ have been observed, the former reacting with water to produce NO, the latter dimerizing to N/sub 2/O/sub 4/. In the presence of O/sub 2/ and unidentified species with absorption maximum at 280 nm, probably a peroxy compound, is being formed. The radiolytic processes occurring in the nitrite solution do not depend on /NO/sub 02// and no effect of the direct energy absorption by NO/sup -//sub 2/ has been noticed. Transient species in the diluted nitrate solution are NO/sup 2 -//sub 3/ and the pernitrous ion; in concentrated solutions NO/sub 3/ is the main transient product. NO/sub 3/ is formed by the direct energy absorption by NO/sup -//sub 3/. Participation in tha effect of the cation should not be disregarded. There is evidence that the 340 nm peak in the transient spectrum is probably connected with N/sub 2/O/sub 4/ and not with NO/sub 3/. The tranient spectra, extinction coefficients of products and rate constants of relevant reactions are given.

Study of nonlinear optical absorption properties of V{sub 2}O{sub 5} nanoparticles in the femtosecond excitation regime

Energy Technology Data Exchange (ETDEWEB)

Molli, Muralikrishna; Bhat Kademane, Abhijit; Pradhan, Prabin; Sai Muthukumar, V. [Sri Sathya Sai Institute of Higher Learning, Department of Physics, Puttaparthi, Andhra Pradesh (India)

2016-08-15

In this work, we report for the first time, the nonlinear optical absorption properties of vanadium pentoxide (V{sub 2}O{sub 5}) nanoparticles in the femtosecond excitation regime. V{sub 2}O{sub 5} nanoparticles were synthesized through solution combustion technique. The as-synthesized samples were further characterized using XRD, FESEM, EDAX, TEM and UV-visible spectroscopy. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies showed the size of the nanoparticles to be ∝200 nm. Open-aperture z-scan technique was employed to study the nonlinear optical absorption behavior of the synthesized samples using a 100-fs laser pulses at 800 nm from a regeneratively amplified Ti: sapphire laser. The mechanism of nonlinear absorption was found to be a three-photon absorption process which was explained using the density of states of V{sub 2}O{sub 5} obtained using density functional theory. These nanoparticles exhibit strong intensity-dependent nonlinear optical absorption and hence could be considered for optical-power-limiting applications. (orig.)

Pulse Compression of Phase-matched High Harmonic Pulses from a Time-Delay Compensated Monochromator

Directory of Open Access Journals (Sweden)

Ito Motohiko

2013-03-01

Full Text Available Pulse compression of single 32.6-eV high harmonic pulses from a time-delay compensated monochromator was demonstrated down to 11±3 fs by compensating the pulse front tilt. The photon flux was intensified up to 5.7×109 photons/s on target by implementing high harmonic generation under a phase matching condition in a hollow fiber used for increasing the interaction length.

Efficient compression of the femtosecond pulses of an ytterbium laser in a gas-filled capillary

International Nuclear Information System (INIS)

Konyashchenko, Aleksandr V; Losev, Leonid L; Tenyakov, S Yu

2011-01-01

A 290-fs radiation pulse of an ytterbium laser system with a central wavelength of 1028 nm and an energy of 145 μJ was compressed to a 27-fs pulse with an energy of 75 μJ. The compression was realised on the basis of the effect of pulse spectrum broadening in a xenon-filled glass capillary for a pulse repetition rate of 3kHz. (control of laser radiation parameters)

Reduction of damage threshold in dielectric materials induced by negatively chirped laser pulses

International Nuclear Information System (INIS)

Louzon, E.; Henis, Z.; Pecker, S.; Ehrlich, Y.; Fisher, D.; Fraenkel, M.; Zigler, A.

2005-01-01

The threshold fluence for laser induced damage in wide band gap dielectric materials, fused silica and MgF 2 , is observed to be lower by up to 20% for negatively (down) chirped pulses than for positively (up) chirped, at pulse durations ranging from 60 fs to 1 ps. This behavior of the threshold fluence for damage on the chirp direction was not observed in semiconductors (silicon and GaAs). Based on a model including electron generation in the conduction band and Joule heating, it is suggested that the decrease in the damage threshold for negatively chirped pulse is related to the dominant role of multiphoton ionization in wide gap materials

ARPES and NMTO Wannier Orbital Theory of Li{sub 0.9}Mo{sub 6}O{sub 17}

Energy Technology Data Exchange (ETDEWEB)

Dudy, L. [Physikalisches Institut, Universitaet Wuerzburg, D- 97074 Wuerzburg (Germany); Allen, J.W. [University of Michigan, Ann Arbor, MI (United States); Denlinger, J.D. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); He, J. [Clemson University, Clemson, SC (United States); Greenblatt, M. [Rutgers University, Piscataway, NJ (United States); Haverkort, M.W. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Andersen, O.K.; Nohara, Y. [Max-Planck-Institut fuer Festkoerperphysik, Stuttgart (Germany)

2015-07-01

Li{sub 0.9}Mo{sub 6}O{sub 17} displays theoretically interesting metallic quasi-one dimensional (1D) behavior that is unusually robust against 3D crossover with decreasing temperature, and is characterized by a large value of anomalous exponent α∼ 0.6. We present very high resolution, low temperature (T=6K-30K) angle resolved photoemission spectroscopy (ARPES) of its band structure and Fermi surface (FS), analyzed with N-th order muffin tin orbital (NMTO) Wannier function band theory. We confirm a previous conclusion that LDA band theory is unusually successful, implying a small Hubbard U, and find in ARPES the dispersion and FS warping and splitting expected for predicted small and long range hoppings (t {sub perpendicular} {sub to} ∼ 10-15 meV) between chains.

Enhanced piezoelectricity in plastically deformed nearly amorphous Bi{sub 12}TiO{sub 20}-BaTiO{sub 3} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Yu, Dan; Zhao, Minglei, E-mail: zhaoml@sdu.edu.cn; Wang, Chunlei; Wang, Lihai; Su, Wenbin; Gai, Zhigang; Wang, Chunming; Li, Jichao; Zhang, Jialiang [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

2016-07-18

Bulk Bi{sub 12}TiO{sub 20}-BaTiO{sub 3} (BTO-BT) nanocomposites are fabricated through the high-temperature interfacial reaction between nanometer-sized BaTiO{sub 3} particles and melting Bi{sub 12}TiO{sub 20}. Although the obtained BTO-BT nanocomposites are nearly amorphous and display very weak ferroelectricity, they exhibit relatively strong piezoelectricity without undergoing the electrical poling process. The volume fraction of crystalline Bi{sub 12}TiO{sub 20} is reduced to less than 10%, and the piezoelectric constant d{sub 33} is enhanced to 13 pC/N. Only the presence of the macroscopic polar amorphous phases can explain this unusual thermal stable piezoelectricity. Combining the results from X-ray diffraction, Raman spectroscopy, and thermal annealing, it can be confirmed that the formation of macroscopic polar amorphous phases is closely related to the inhomogeneous plastic deformation of the amorphous Bi{sub 12}TiO{sub 20} during the sintering process. These results highlight the key role of plastically deformed amorphous Bi{sub 12}TiO{sub 20} in the Bi{sub 12}TiO{sub 20}-based polar composites, and the temperature gradient driven coupling between the plastic strain gradient and polarization in amorphous phases is the main poling mechanism for this special type of bulk polar material.

The affect of erbium hydride on the conversion efficience to accelerated protons from ultra-shsort pulse laser irradiated foils

Energy Technology Data Exchange (ETDEWEB)

Offermann, Dustin Theodore [The Ohio State Univ., Columbus, OH (United States)

2008-01-01

This thesis work explores, experimentally, the potential gains in the conversion efficiency from ultra-intense laser light to proton beams using erbium hydride coatings. For years, it has been known that contaminants at the rear surface of an ultra-intense laser irradiated thin foil will be accelerated to multi-MeV. Inertial Confinement Fusion fast ignition using proton beams as the igniter source requires of about 10¹⁶ protons with an average energy of about 3MeV. This is far more than the 10¹² protons available in the contaminant layer. Target designs must include some form of a hydrogen rich coating that can be made thick enough to support the beam requirements of fast ignition. Work with computer simulations of thin foils suggest the atomic mass of the non-hydrogen atoms in the surface layer has a strong affect on the conversion efficiency to protons. For example, the 167amu erbium atoms will take less energy away from the proton beam than a coating using carbon with a mass of 12amu. A pure hydrogen coating would be ideal, but technologically is not feasible at this time. In the experiments performed for my thesis, ErH<sub>3sub> coatings on 5 μm gold foils are compared with typical contaminants which are approximately equivalent to CH<sub>1.7sub>. It will be shown that there was a factor of 1.25 ± 0.19 improvement in the conversion efficiency for protons above 3MeV using erbium hydride using the Callisto laser. Callisto is a 10J per pulse, 800nm wavelength laser with a pulse duration of 200fs and can be focused to a peak intensity of about 5 x 10¹⁹W/cm². The total number of protons from either target type was on the order of 10¹⁰. Furthermore, the same experiment was performed on the Titan laser, which has a 500fs pulse duration, 150J of energy and can be focused to about 3 x 10²⁰ W/cm². In this experiment 10¹² protons were seen from both erbium hydride and

Generation of Attosecond Light Pulses from Gas and Solid State Media

Directory of Open Access Journals (Sweden)

Stefanos Chatziathanasiou

2017-03-01

Full Text Available Real-time observation of ultrafast dynamics in the microcosm is a fundamental approach for understanding the internal evolution of physical, chemical and biological systems. Tools for tracing such dynamics are flashes of light with duration comparable to or shorter than the characteristic evolution times of the system under investigation. While femtosecond (fs pulses are successfully used to investigate vibrational dynamics in molecular systems, real time observation of electron motion in all states of matter requires temporal resolution in the attosecond (1 attosecond (asec = 10−18 s time scale. During the last decades, continuous efforts in ultra-short pulse engineering led to the development of table-top sources which can produce asec pulses. These pulses have been synthesized by using broadband coherent radiation in the extreme ultraviolet (XUV spectral region generated by the interaction of matter with intense fs pulses. Here, we will review asec pulses generated by the interaction of gas phase media and solid surfaces with intense fs IR laser fields. After a brief overview of the fundamental process underlying the XUV emission form these media, we will review the current technology, specifications and the ongoing developments of such asec sources.

Fabrication of TiNb{sub 2}O{sub 7} thin film electrodes for Li-ion micro-batteries by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Daramalla, V. [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India); Penki, Tirupathi Rao; Munichandraiah, N. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengalore 560012 (India); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India)

2016-11-15

Graphical abstract: The TiNb{sub 2}O{sub 7} thin film electrodes as anode material in Li-ion rechargeable micro-batteries are successfully demonstrated. The pulsed laser deposited TiNb{sub 2}O{sub 7} thin film electrode delivers high discharge specific capacity of 143 μAh μm{sup −1} cm{sup −2} at 50 μA cm{sup −2} current density, with 92% coulombic efficiency. The thin films are very stable in crystal structure, with good fast reversible reaction at average Li-insertion voltage 1.65 V. - Highlights: • TiNb{sub 2}O{sub 7} thin films fabricated by pulsed laser deposition. • TiNb{sub 2}O{sub 7} as anode thin films demonstrated successfully. • High discharge specific capacity with 92% coulombic efficiency. • Excellent crystal stability and good reversible reaction. - Abstract: Pulsed laser deposited TiNb{sub 2}O{sub 7} thin films are demonstrated as anode materials in rechargeable Li-ion micro-batteries. The monoclinic and chemically pure TiNb{sub 2}O{sub 7} films in different morphologies were successfully deposited at 750 °C. The single phase formation was confirmed by grazing incident X-ray diffraction, micro-Raman spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The oxygen partial pressure during the deposition significantly influenced the properties of TiNb{sub 2}O{sub 7} films. The TiNb{sub 2}O{sub 7} thin films exhibited excellent stability with fast kinetics reversible reaction. The TiNb{sub 2}O{sub 7} films showed initial discharge specific capacity of 176, 143 μAh μm{sup −1} cm{sup −2} at 30, 50 μA cm{sup −2} current densities respectively with 92% coulombic efficiency in a non-aqueous electrolyte consisting of Li{sup +} ions. The high discharge specific capacity of TiNb{sub 2}O{sub 7} thin films may be attributed to nanometer grain size with high roughness which offers high surface area for Li-diffusion during charge and discharge

Design of a 2 kA, 30 fs Rf-Photoinjector for Waterbag Compression

Science.gov (United States)

van der Geer, S. B.; Luiten, O. J.; de Loos, M. J.

Because uniformly filled ellipsoidal ‘waterbag’ bunches have linear self-fields in all dimensions, they do not suffer from space-charge induced brightness degradation. This in turn allows very efficient longitudinal compression of high-brightness bunches at sub or mildly relativistic energies, a parameter regime inaccessible up to now due to detrimental effects of non-linear space-charge forces. To demonstrate the feasibility of this approach, we investigate ballistic bunching of 1 MeV, 100 pC waterbag electron bunches, created in a half-cell rf-photogun, by means of a two-cell booster-compressor. Detailed GPT simulations of this table-top set-up are presented, including realistic fields, 3D space-charge effects, path-length differences and image charges at the cathode. It is shown that with a single 10MW S-band klystron and fields of 100 MV/m, 2kA peak current is attainable with a pulse duration of only 30 fs at a transverse normalized emittance of 1.5 μm.

EST Table: FS891235 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS891235 E_FL_ftes_02B20_R_0 11/12/09 GO hit GO:0003779(actin binding)|GO:0007010(cytoskeleton... organization)|GO:0015629(actin cytoskeleton)|GO:0030036(actin cytoskeleton organization) 10/09/2

Impact of pumping configuration on all-fibered femtosecond chirped pulse amplification

Science.gov (United States)

Lecourt, Jean-Bernard; Duterte, Charles; Bertrand, Anthony; Liégeois, Flavien; Hernandez, Yves; Giannone, Domenico

2008-04-01

We experimentally compared the co- and counter-propagative pumping scheme for the amplification of ultra-short optical pulses. According to pumping direction we show that optical pulses with a duration of 75 fs and 100mW of average output power can be obtained for co-propagative pumping, while pulse duration is never shorter than 400 fs for the counter-propagative case. We show that the impact of non-linear effects on pulse propagation is different for the two pumping configurations. We assume that Self Phase Modulation (SPM) is the main effect in the copropagative case, whereas the impact of Stimulated Raman Scattering is bigger for the counter-propagative case.

Trapping and breaking of in vivo nicked DNA during pulsed-field gel electrophoresis

Science.gov (United States)

Khan, Sharik R.; Kuzminov, Andrei

2013-01-01

Pulsed field gel electrophoresis (PFGE) offers a high-resolution approach to quantify chromosomal fragmentation in bacteria, measured as percent of chromosomal DNA entering the gel. The degree of separation in PFG depends upon the size of DNA, as well as various conditions of electrophoresis, such as electric field strength (FS), time of electrophoresis, switch time and buffer composition. Here we describe a new parameter, the structural integrity of the sample DNA itself, that influences its migration through PFGs. We show that sub-chromosomal fragments containing both spontaneous and DNA damage-induced nicks are prone to breakage during PFGE. Such breakage at single strand interruptions results in artefactual decrease in molecular weight of linear DNA making accurate determination of the number of double strand breaks difficult. While breakage of nicked sub-chromosomal fragments is FS-independent, some high molecular weight sub-chromosomal fragments are also trapped within wells under the standard PFGE conditions. This trapping can be minimized by lowering the field strength and increasing the time of electrophoresis. We discuss how breakage of nicked DNA may be mechanistically linked to trapping. Our results suggest how to optimize conditions for PFGE when quantifying chromosomal fragmentation induced by DNA damage. PMID:23770235

Hydrogenation study of suction-cast Ti{sub 40}Zr{sub 40}Ni{sub 20} quasicrystal

Energy Technology Data Exchange (ETDEWEB)

Huang, Huogen; Li, Rong; Yin, Chen; Zheng, Shaotao; Zhang, Pengcheng [National Key Laboratory for Surface Physics and Chemistry, P.O. Box 718-35, Mian Yang 621907, Sichuan (China)

2008-09-15

Suction casting was predicted to be an usable method for improving the hydriding kinetics of Ti/Zr-based icosahedral quasicrystals (IQCs) in our previous work. To further determine it, a suction-cast Ti{sub 40}Zr{sub 40}Ni{sub 20} IQC alloy was used for hydrogenation studies by Pressure Composition Isotherm (PCI) and Temperature Programmed Desorption (TPD) techniques. The results showed that, this alloy absorbed hydrogen rapidly with obvious hydrogen pressure plateau and some reversibility, however, displayed very limited hydrogen capacity (about 0.7 wt.%) and low equilibrium pressure. After several hydrogenation/dehydrogenation cycles, the IQC structure transformed into two hydride phases, ZrH{sub 2-x} and one unknown, both of which decomposed at above 600 C, suggesting high thermo-stability for them. On the whole, indeed the suction-casting method can increase the hydrogen absorption rate of Ti/Zr-based IQCs, however, the hydrogenation properties of the Ti{sub 40}Zr{sub 40}Ni{sub 20} IQC alloy still need a mighty advancement. (author)

Fs–ns double-pulse Laser Induced Breakdown Spectroscopy of copper-based-alloys: Generation and elemental analysis of nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Guarnaccio, A.; Parisi, G.P.; Mollica, D. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); De Bonis, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy); Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Teghil, R. [Dipartimento di Scienze, Università degli Studi della Basilicata, Via dell' Ateneo Lucano 10, 85100 Potenza (Italy); Santagata, A. [CNR-ISM, U.O.S. Tito Scalo, Zona Industriale, 85050 Tito Scalo, PZ (Italy)

2014-11-01

Evolution of nanoparticles ejected during ultra-short (250 fs) laser ablation of certified copper alloys and relative calibration plots of a fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration is presented. All work was performed in air at atmospheric pressure using certified copper-based-alloy samples irradiated by a fs laser beam and followed by a delayed perpendicular ns laser pulse. In order to evaluate possible compositional changes of the fs induced nanoparticles, it was necessary to consider, for all samples used, comparable features of the detected species. With this purpose the induced nanoparticles black-body-like emission evolution and their relative temperature decay have been studied. These data were exploited for defining the distance between the target surface and the successive ns laser beam to be used. The consequent calibration plots of minor constituents (i.e. Sn, Pb and Zn) of the certified copper-based-alloy samples have been reported by taking into account self-absorption effects. The resulting linear regression coefficients suggest that the method used, for monitoring and ruling the fs laser induced nanoparticles, could provide a valuable approach for establishing the occurrence of potential compositional changes of the detected species. All experimental data reveal that the fs laser induced nanoparticles can be used for providing a coherent composition of the starting target. In the meantime, the fs–ns double-pulse Laser Induced Breakdown Spectroscopy orthogonal configuration here used can be considered as an efficient technique for compositional determination of the nanoparticles ejected during ultra-short laser ablation processes. - Highlights: • Laser induced NP continuum black-body-like emission was used for T determination. • Invariable composition of generated NPs was assumed in the range of 20 μs. • Fs-ns DP-LIBS was employed for the compositional characterization of NPs. • NPs obtained by fs

EST Table: FS758854 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS758854 E_FL_fcaL_09I20_F_0 10/09/28 35 %/195 aa ref|XP_001842174.1| sensitized chromosome inheritance... modifier 19 [Culex quinquefasciatus] gb|EDS39679.1| sensitized chromosome inheritance m

Multiferroic and visible light photocatalytic properties of six-layered perovskite oxide Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20}

Energy Technology Data Exchange (ETDEWEB)

Cheng, Xiangyi; Yang, Hongshun; Ruan, Keqing; Xu, Xiaoliang [University of Science and Technology of China, Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and School of Physical Sciences, Hefei (China); Meng, Dechao [University of Science and Technology of China, Hefei National Laboratory for Physical Sciences at Microscale, Hefei (China)

2017-04-15

The layered perovskite-related oxide Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20} was prepared by incorporating NdFeO{sub 3} in the host Nd{sub 2}Ti{sub 2}O{sub 7} using floating-zone melting technique. XRD and HRTEM results suggested that the material has a layered structure of n = 6 type. Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20} exhibited spin glass-like behavior, and its magnetic behavior was affected by magnetic Nd{sup 3+} ions strongly at low temperature. The ferromagnetic and ferroelectric properties were observed by magnetic and PFM measurements at the room temperature. UV-Vis absorption spectroscopy revealed that the compound is a visible light absorbing photocatalyst with a direct band gap of 2.2 eV. In addition, the photocatalytic behaviors of bulk Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20} were evaluated by photodegradation of rhodamine B under visible light irradiation. (orig.)

2.5 TW, two-cycle IR laser pulses via frequency domain optical parametric amplification.

Science.gov (United States)

Gruson, V; Ernotte, G; Lassonde, P; Laramée, A; Bionta, M R; Chaker, M; Di Mauro, L; Corkum, P B; Ibrahim, H; Schmidt, B E; Legaré, F

2017-10-30

Broadband optical parametric amplification in the IR region has reached a new milestone through the use of a non-collinear Frequency domain Optical Parametric Amplification system. We report a laser source delivering 11.6 fs pulses with 30 mJ of energy at a central wavelength of 1.8 μm at 10 Hz repetition rate corresponding to a peak power of 2.5 TW. The peak power scaling is accompanied by a pulse shortening of about 20% upon amplification due to the spectral reshaping with higher gain in the spectral wings. This source paves the way for high flux soft X-ray pulses and IR-driven laser wakefield acceleration.

Repetitively pulsed TEA CO{sub 2} laser and its application for second harmonic generation in ZnGeP{sub 2} crystal

Energy Technology Data Exchange (ETDEWEB)

Koval' chuk, L V; Grezev, A N; Niz' ev, V G; Yakunin, V P [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation); Mezhevov, V S [Kaluga Laser Innovation and Technology Centre, Obninsk, Kaluga region (Russian Federation); Goryachkin, D A [Russian State Scientific Center for Robotics and Technical Cybernetics, St. Petersburg (Russian Federation); Sergeev, V V; Kalintsev, A G [Open Joint Stock Company S.I.Vavilov State Optical Institute, St. Petersburg (Russian Federation)

2015-10-31

Experimental results are presented on the development of a radiation source emitting at a wavelength of 4.775 μm with a pulse energy up to 50 mJ and an average power up to several watts in short pulse trains. A TEA CO{sub 2} laser and a nonlinear converter based on a ZnGeP{sub 2} crystal, which are specially designed for these experiments, are described. The main limitations of nonlinear conversion and possible ways to overcome these limitations are considered. (lasers)

SeaWiFS

Data.gov (United States)

Washington University St Louis — SEAWiFS_US is a high resolution (1km) satellite dataset derived from the eight wavelength SEAWiFS sensor. The dataset also includes the aerosol reflectance over the...

Optimization of electrodeposited p-doped Sb{sub 2}Te{sub 3} thermoelectric films by millisecond potentiostatic pulses

Energy Technology Data Exchange (ETDEWEB)

Schumacher, Christian; Akinsinde, Lewis; Zastrow, Sebastian; Heiderich, Sonja; Toellner, William; Nielsch, Kornelius; Bachmann, Julien [Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany); Reinsberg, Klaus G.; Broekaert, Jose A.C. [Institute of Applied and Inorganic Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg (Germany); Rampelberg, Geert; Detavernier, Christophe [Department of Solid State Sciences, University of Ghent, Krijgslaan 281/S1, 9000 Ghent (Belgium)

2012-03-15

A systematic optimization of p-type Sb{sub 2}Te{sub 3} thermoelectric films made by potentiostatic electrodeposition on Au and stainless steel substrates is presented. The influence of the preparative parameters of deposition voltage, concentration, and the deposition method are investigated in a nitric acid solution. As a postdeposition step, the influence of annealing the films is investigated. The use of a potential-controlled millisecond-pulsed deposition method could improve both the morphology and the composition of the films. The samples are characterized in terms of composition, crystallinity, Seebeck coefficient, and electrical resistivity. Pulsed-deposited films exhibit Seebeck coefficients of up to 160 {mu}V K{sup -1} and an electrical conductivity of 280 S cm{sup -1} at room temperature, resulting in power factors of about 700 {mu}W m{sup -1} K{sup -2}. After annealing, power factors of maximum 852 {mu}W m{sup -1} K{sup -2} are achieved. Although the annealing of DC-deposited films significantly increased the power factor, they do not reach the values of the pulsed-deposited films in the preannealing state. Structural analysis is performed with X-ray diffraction and shows the crystalline structure of Sb{sub 2}Te{sub 3} films. The performance is tuned by annealing of deposited films up to 300 C under He atmosphere while performing in-situ X-ray diffraction and resistivity measurements. The chemical analysis of the films is performed by inductively coupled plasma optical emission spectroscopy (ICP-OES) as well as scanning electron microscope energy dispersive X-ray analysis (SEM-EDX). (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Study and realisation of a femtosecond dye laser operating at different wavelengths. Ultrashort pulses compression and amplification; Etude et realisation d'un laser a colorant femtoseconde fonctionnant a differentes longueurs d'onde. Compression et amplification d'impulsions ultrabreves

Energy Technology Data Exchange (ETDEWEB)

Georges, Patrick

1989-12-21

We present the study and the realization of a passively mode-locked dye laser producing pulses shorter than 100 femto-seconds (10{sup -13} s). In a ring cavity with an amplifier medium (Rhodamine 60) and a saturable absorber (DODCI), a sequence of four prisms controls the group velocity dispersion and allows the generation of very short pulses. Then we have studied the production of femtosecond pulses at other wavelengths directly from the femtosecond dye laser. For the first rime, 60 fs pulses at 685 nm and pulses shorter than 50 fs between 775 nm and 800 nm have been produced by passive mode locking. These near infrared pulses have been used to study the absorption saturation kinetics in semiconductors multiple quantum wells GaAs/GaAlAs. We have observed a singular behavior of the laser operating at 685 nm and analyzed the produced pulses in terms of optical solitons. To perform time resolved spectroscopy with shortest pulses, we have studied a pulse compressor and a multipass amplifier to increase the pulses energy. Pulses of 20 fs and 10 micro-joules (peak power: 0.5 GW) have been obtained at low repetition rate (10 Hz) and pulses of 16 fs and 0.6 micro-joules pulses have been generated at high repetition rate (11 kHz) using a copper vapor laser. These pulses have been used to study the absorption saturation kinetics of an organic dye (the Malachite Green). (author) [French] Ce memoire presente l'etude et la realisation d'un laser a colorant a verrouillage de modes passif produisant des impulsions de 100 femtosecondes (10- 13 s). Dans une cavite en anneau contenant un milieu amplificateur (Rhodamine 60) et un absorbant saturable (DODCI), un systeme de prismes permettant de controler la dispersion de vitesse de groupe realise une mise en phase de toutes les frequences du spectre des impulsions. Nous avons ensuite etudie la possibilite de produire des impulsions femtosecondes a d'autres longueurs d'onde directement avec l'oscillateur. Des impulsions de 60 fs a

Short pulse absorption dynamics in a p-i-n InGaAsP MQW waveguide saturable absorber

DEFF Research Database (Denmark)

Romstad, Francis Pascal; Öhman, Filip; Mørk, Jesper

2002-01-01

The saturation properties and absorption dynamics of an InGaAsP MQW waveguide saturable absorber is measured using short 200-fs and 1-ps pulses. The dependence on the pulse energy and reverse bias is characterized.......The saturation properties and absorption dynamics of an InGaAsP MQW waveguide saturable absorber is measured using short 200-fs and 1-ps pulses. The dependence on the pulse energy and reverse bias is characterized....

High impact ionization rate in silicon by sub-picosecond THz electric field pulses (Conference Presentation)

DEFF Research Database (Denmark)

Tarekegne, Abebe Tilahun; Iwaszczuk, Krzysztof; Hirori, Hideki

2017-01-01

Summary form only given. Metallic antenna arrays fabricated on high resistivity silicon are used to localize and enhance the incident THz field resulting in high electric field pulses with peak electric field strength reaching several MV/cm on the silicon surface near the antenna tips. In such high...... electric field strengths high density of carriers are generated in silicon through impact ionization process. The high density of generated carriers induces a change of refractive index in silicon. By measuring the change of reflectivity of tightly focused 800 nm light, the local density of free carriers...... near the antenna tips is measured. Using the NIR probing technique, we observed that the density of carriers increases by over 8 orders of magnitude in a time duration of approximately 500 fs with an incident THz pulse of peak electric field strength 700 kV/cm. This shows that a single impact...

Morphology and structural studies of WO{sub 3} films deposited on SrTiO{sub 3} by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Kalhori, Hossein, E-mail: h.kalhori@ph.iut.ac.ir [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Department of Physics, Isfahan University of Technology, Isfahan 84156-8311 (Iran, Islamic Republic of); Porter, Stephen B.; Esmaeily, Amir Sajjad; Coey, Michael [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Ranjbar, Mehdi; Salamati, Hadi [Department of Physics, Isfahan University of Technology, Isfahan 84156-8311 (Iran, Islamic Republic of)

2016-12-30

Highlights: • Highly oriented WO{sub 3} stoichiometric films were determined using pulsed laser deposition method. • Effective parameters on thin films including temperature, oxygen partial pressure and laser energy fluency was studied. • A phase transition was observed in WO{sub 3} films at 700 °C from monoclinic to tetragonal. - Abstract: WO{sub 3} films have been grown by pulsed laser deposition on SrTiO{sub 3} (001) substrates. The effects of substrate temperature, oxygen partial pressure and energy fluence of the laser beam on the physical properties of the films were studied. Reflection high-energy electron diffraction (RHEED) patterns during and after growth were used to determine the surface structure and morphology. The chemical composition and crystalline phases were obtained by XPS and XRD respectively. AFM results showed that the roughness and skewness of the films depend on the substrate temperature during deposition. Optimal conditions were determined for the growth of the highly oriented films.

Stress-induced buried waveguides in the 0.8CaSiO{sub 3}–0.2Ca{sub 3}(PO{sub 4}){sub 2} eutectic glass doped with Nd{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Sola, D., E-mail: dsola@unizar.es [Centro de Física de Materiales, CSIC-UPV/EHU, P° Manuel de Lardizabal, 5, 20.018 San Sebastián (Spain); Martínez de Mendibil, J. [Departamento de Física de Materiales, C-04, Facultad de Ciencias, Universidad Autónoma de Madrid, 28.049 Madrid (Spain); Vázquez de Aldana, J.R. [Grupo de Óptica, Facultad de Ciencias, Universidad de Salamanca, 37.008 Salamanca (Spain); Lifante, G. [Departamento de Física de Materiales, C-04, Facultad de Ciencias, Universidad Autónoma de Madrid, 28.049 Madrid (Spain); Balda, R. [Centro de Física de Materiales, CSIC-UPV/EHU, P° Manuel de Lardizabal, 5, 20.018 San Sebastián (Spain); Departamento de Física Aplicada I, E.T.S. Ingeniería de Bilbao, UPV/EHU, Alda. de Urquijo s/n, 48.013 Bilbao (Spain); Aza, A.H. de; Pena, P. [Instituto de Cerámica y Vidrio, CSIC, C/Kelsen 5, 28.049 Madrid (Spain); Fernández, J. [Centro de Física de Materiales, CSIC-UPV/EHU, P° Manuel de Lardizabal, 5, 20.018 San Sebastián (Spain); Departamento de Física Aplicada I, E.T.S. Ingeniería de Bilbao, UPV/EHU, Alda. de Urquijo s/n, 48.013 Bilbao (Spain)

2013-08-01

In this work the fabrication of buried optical waveguides by femtosecond laser inscription in the 0.8CaSiO{sub 3}–0.2Ca{sub 3}(PO{sub 4}){sub 2} eutectic glass doped with Nd{sup 3+} ions is reported. The glass samples were prepared by melting the eutectic powder mixture in a Pt–10 wt.% Rh crucible at 1600 °C and pouring it in a preheated brass mould. Afterwards, the glass was annealed to release the inner stresses. Buried waveguides were fabricated by focusing beneath the surface a pulsed Ti:sapphire laser with a pulsewidth of 120 fs working at 1 kHz. Two adjacent parallel tracks were written to define a region where an increase in the refractive index occurs. The effects produced by the variation of the laser pulse energy as well as the lateral separation between tracks, scanning speed and focusing distance were studied. After the laser processing, the near-field intensity distribution at 633 nm of the waveguide's modes was studied demonstrating the confinement of both, the TE as the TM polarizations. In order to diminish the losses induced by colour centres absorption, heat treatments were carried out in the samples. The waveguide's modes were compared with respect to the samples without heat treatments. The spectroscopic properties of the neodymium ions have been characterized to evaluate in what extent their optical properties could be modified by the waveguide fabrication process and to elucidate the potential application of such waveguides as integrated laser sources.

Effect of annealing on structural and optical properties of Cu{sub 2}ZnSnS{sub 4} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Surgina, G.D., E-mail: silvereye@bk.ru [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Nevolin, V.N. [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); Sipaylo, I.P.; Teterin, P.E. [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); Medvedeva, S.S. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Lebedinsky, Yu.Yu.; Zenkevich, A.V. [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation)

2015-11-02

In this work, we compare the effect of different types of thermal annealing on the morphological, structural and optical properties of Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films grown by reactive Pulsed Laser Deposition in H{sub 2}S flow. Rutherford backscattering spectrometry, atomic force microscopy, X-ray diffraction, Raman spectroscopy and optical spectrophotometry data reveal dramatic increase of the band gap and the crystallite size without the formation of secondary phases upon annealing in N{sub 2} at the optimized conditions. - Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films were grown at room temperature. • Reactive Pulsed Laser Deposition in H{sub 2}S flow was used as a growth method. • Effect of annealing conditions on CZTS structural and optical properties is revealed. • Both the grain size and the band gap of CZTS film increase following the annealing. • Annealing in N{sub 2} effectively inhibits the formation of Sn{sub x}S secondary phases.

Epitaxial growth of Sc{sub 2}O{sub 3} films on Gd{sub 2}O{sub 3}-buffered Si substrates by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Paulraj, Joseph; Wang, Rongping; Sellars, Matthew; Luther-Davies, Barry [Australian National University, Laser Physics Centre, Research School of Physics and Engineering, Acton, Canberra, ACT (Australia)

2016-04-15

We investigated the optimal conditions to prepare high-quality Sc{sub 2}O{sub 3} films on Gd{sub 2}O{sub 3}-buffered Si wafers using pulsed laser deposition technique with an aim at developing waveguide devices that can transform the performance of the gradient echo quantum memory based on bulk crystals. Under the optimal conditions, only oxide and Si (2 2 2) peaks appeared in the X-ray diffraction pattern. The Sc{sub 2}O{sub 3} (2 2 2) diffraction peak was located at 2θ=31.5 with a full width at half maxima (FWHM) of 0.16 , and its rocking curve had a FWHM of 0.10 . In-plane epitaxial relationship was confirmed by X-ray pole figure where Sc{sub 2}O{sub 3} (1 1 1) was parallel to Si (1 1 1). High-resolution TEM images indicated clear interfaces and perfect lattice images with sharp electron diffraction dots. All these results confirm that the oxide films on Si were single crystalline with high quality. (orig.)

Moessbauer spectroscopy on amorphous Fe/sub x/Ni/sub 80-x/B/sub 20/ after neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Sitek, J.; Miglierini, M. (Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia))

1985-05-16

Amorphous Fe/sub x/Ni/sub 80-x/B/sub 20/ glassy alloys (x = 40, 50, 60, and 70) irradiated with fast neutrons in a fluence range of 10/sup 14/ to 10/sup 19/ cm/sup -2/ were investigated by Moessbauer spectroscopy. There were some significant changes in the Moessbauer spectrum parameters of the 10/sup 19/ cm/sup -2/ irradiated samples except Fe/sub 40/Ni/sub 40/B/sub 20/. This corresponds to a change in the direction of the easy axis of magnetization. The measurements show that the resistance of the Fe-Ni-B system against neutron irradiation improves with increasing Ni content up to a certain point.

Picosecond ion pulses from an EN tandem created by a femtosecond Ti:sapphire laser

International Nuclear Information System (INIS)

Carnes, K.D.; Cocke, C.L.; Chang, Z.; Ben-Itzhak, I.; Needham, H.V.; Rankin, A.

2007-01-01

As the James R. Macdonald Laboratory at Kansas State University continues its transformation from an ion collisions facility to an ultrafast laser/ion collisions facility, we are looking for novel ways to combine our traditional accelerator expertise with our new laser capabilities. One such combination is to produce picosecond pulses of stripping gas ions in the high energy accelerating tube of our EN tandem by directing ∼100 fs, sub-milliJoule laser pulses up the high energy end of the tandem toward a focusing mirror at the terminal. Ion pulses from both stripping and residual gas have been produced and identified, with pulse widths thus far on the order of a nanosecond. This width represents an upper limit, as it is dominated by pulse-to-pulse jitter in the ion time-of-flight (TOF) and is therefore not a true representation of the actual pulse width. In this paper, we describe the development process and report on the results to date. Conditions limiting the minimum temporal pulse width, such as tandem terminal ripple, thermal motion of the gas and space charge effects, are also outlined

Frequency conversion of high-intensity, femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Banks, P S

1997-06-01

Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

Out-of-plane coercive field of Ni{sub 80}Fe{sub 20} antidot arrays

Energy Technology Data Exchange (ETDEWEB)

Chunhong, Gao [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Ke, Chen [Chongqing Electric Power College, Chongqing (China); Ling, Lue; Jianwei, Zhao [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Chen Peng, E-mail: pchen@swu.edu.c [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China)

2010-11-15

The out-of-plane magnetic anisotropy and out-of-plane magnetization reversal process of nanoscale Ni{sub 80}Fe{sub 20} antidot arrays deposited by magnetron sputtering technique on an anodic aluminum oxide (AAO) membrane are investigated. The angular dependence of out-of-plane remanent magnetization of Ni{sub 80}Fe{sub 20} antidot arrays shows that the maximum remanence is in-plane and the squareness of the out-of-plane hysteresis loop follow a |cos {theta}| dependence. The angular dependence of out-of-plane coercivity of Ni{sub 80}Fe{sub 20} antidot arrays shows that the maximum coercivity lies on the surface of a cone with its symmetric axis normal to the sample plane, which indicates a transition of magnetic reversal from curling to coherent rotation when changing the angle between the applied magnetic field and the sample plane.

Visible continuum pulses based on enhanced dispersive wave generation for endogenous fluorescence imaging.

Science.gov (United States)

Cui, Quan; Chen, Zhongyun; Liu, Qian; Zhang, Zhihong; Luo, Qingming; Fu, Ling

2017-09-01

In this study, we demonstrate endogenous fluorescence imaging using visible continuum pulses based on 100-fs Ti:sapphire oscillator and a nonlinear photonic crystal fiber. Broadband (500-700 nm) and high-power (150 mW) continuum pulses are generated through enhanced dispersive wave generation by pumping femtosecond pulses at the anomalous dispersion region near zero-dispersion wavelength of high-nonlinear photonic crystal fibers. We also minimize the continuum pulse width by determining the proper fiber length. The visible-wavelength two-photon microscopy produces NADH and tryptophan images of mice tissues simultaneously. Our 500-700 nm continuum pulses support extending nonlinear microscopy to visible wavelength range that is inaccessible to 100-fs Ti:sapphire oscillators and other applications requiring visible laser pulses.

Pulse height measurements and electron attachment in drift chambers operated with Xe,CO{sub 2} mixtures

Energy Technology Data Exchange (ETDEWEB)

Andronic, A. E-mail: a.andronic@gsi.de; Appelshaeuser, H.; Blume, C.; Braun-Munzinger, P.; Bucher, D.; Busch, O.; Ramirez, A.C.A. Castillo; Catanescu, V.; Ciobanu, M.; Daues, H.; Devismes, A.; Emschermann, D.; Fateev, O.; Garabatos, C.; Herrmann, N.; Ivanov, M.; Mahmoud, T.; Peitzmann, T.; Petracek, V.; Petrovici, M.; Reygers, K.; Sann, H.; Santo, R.; Schicker, R.; Sedykh, S.; Shimansky, S.; Simon, R.S.; Smykov, L.; Soltveit, H.K.; Stachel, J.; Stelzer, H.; Tsiledakis, G.; Vulpescu, B.; Wessels, J.P.; Windelband, B.; Winkelmann, O.; Xu, C.; Zaudtke, O.; Zanevsky, Yu.; Yurevich, V

2003-02-11

We present pulse height measurements in drift chambers operated with Xe,CO{sub 2} gas mixtures. We investigate the attachment of primary electrons on oxygen and SF{sub 6} contaminants in the detection gas. The measurements are compared with simulations of properties of drifting electrons. We present two methods to check the gas quality: gas chromatography and {sup 55}Fe pulse height measurements using monitor detectors.

Vertical Bridgman growth and characterization of Cd<sub>0.95-xsub>Mn_xZn>0.05sub>Te (x=0.20, 0.30) single-crystal ingots

Energy Technology Data Exchange (ETDEWEB)

Bolotnikov, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Kopach, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Kopach, O. [Brookhaven National Lab. (BNL), Upton, NY (United States); Shcherbak, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fochuk, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Filonenko, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); James, R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2017-08-01

Solid-liquid phase transitions in Cd<sub>0.95-xsub>Mn_xZn>0.05sub>Te alloys with x = 0.20 and 0.30 were investigated by differential thermal analysis (DTA). The heating/cooling rates were 5 and 10 K/min with a melt dwell time of 10, 30 and 60 minutes. Cd<sub>0.95-xsub>Mn_xZn>0.05sub>Te (x=0.20, 0.30) single-crystal ingots were grown by the vertical Bridgman method guided using the DTA results. Te inclusions (1-20 microns), typical for CdTe and Cd(Zn)Te crystals, were observed in the ingots by infrared transmission microscopy. The measured X-ray diffraction patterns showed that all compositions are found to be in a single phase. Using current-voltage (I-V) measurements, the resistivity of the samples from each ingot was estimated to be about 10⁵ Ohm·cm. The optical transmission analysis demonstrated that the band-gap width of the investigated ingots increased from 1.77 to 1.88 eV with the increase of the MnTe content from 20 to 30 mol. %.

Measuring the electric field of few-cycle laser pulses by attosecond cross correlation

International Nuclear Information System (INIS)

Bandrauk, Andre D.; Chelkowski, Szczepan; Shon, Nguyen Hong

2002-01-01

A new technique for directly measuring the electric field of linearly polarized few-cycle laser pulses is proposed. Based on the solution of the time-dependent Schroedinger equation (TDSE) for an H atom in the combined field of infrared (IR) femtosecond (fs) and ultraviolet (UV) attosecond (as) laser pulses we show that, as a function of the time delay between two pulses, the difference (or equivalently, asymmetry) of photoelectron signals in opposite directions (along the polarization vector of laser pulses) reproduces very well the profile of the electric field (or vector potential) in the IR pulse. Such ionization asymmetry can be used for directly measuring the carrier-envelope phase difference (i.e., the relative phase of the carrier frequency with respect to the pulse envelope) of the IR fs laser pulse

Design and implementation of a fs-resolved transmission electron microscope based on thermionic gun technology

Energy Technology Data Exchange (ETDEWEB)

Piazza, L., E-mail: luca.piazza@epfl.ch [Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), ICMP, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Masiel, D.J. [Integrated Dynamic Electron Solutions, Inc., 455 Bolero Drive, Danville, CA 94526 (United States); LaGrange, T.; Reed, B.W. [Condensed Matter and Materials Division Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Barwick, B. [Department of Physics, Trinity College, 300 Summit St., Hartford, CT 06106 (United States); Carbone, Fabrizio [Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES), ICMP, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland)

2013-09-23

Highlights: • We present the implementation of a femtosecond-resolved ultrafast TEM. • This is the first ultrafast TEM based on a thermionic gun geometry. • An additional condenser lens has been used to maximize the electron count. • We achieved a time resolution of about 300 fs and an energy resolution of 1 eV. - Abstract: In this paper, the design and implementation of a femtosecond-resolved ultrafast transmission electron microscope is presented, based on a thermionic gun geometry. Utilizing an additional magnetic lens between the electron acceleration and the nominal condenser lens system, a larger percentage of the electrons created at the cathode are delivered to the specimen without degrading temporal, spatial and energy resolution significantly, while at the same time maintaining the femtosecond temporal resolution. Using the photon-induced near field electron microscopy effect (PINEM) on silver nanowires the cross-correlation between the light and electron pulses was measured, showing the impact of the gun settings and initiating laser pulse duration on the electron bunch properties. Tuneable electron pulses between 300 fs and several ps can be obtained, and an overall energy resolution around 1 eV was achieved.

Synthesis and Structure Determination of a New Au<sub>20sub> Nanocluster Protected by Tripodal Tetraphosphine Ligands

Energy Technology Data Exchange (ETDEWEB)

Chen, Jing [Brown Univ., Providence, RI (United States); Zhang, Qianfan [Brown Univ., Providence, RI (United States); Williard, Paul G. [Brown Univ., Providence, RI (United States); Wang, Lai-Sheng [Brown Univ., Providence, RI (United States)

2014-03-31

We report the synthesis and structure determination of a new Au<sub>20sub> nanocluster coordinated by four tripodal tetraphosphine (PP<sub>3sub>) ligands {PP<sub>3sub> = tris[2-(diphenylphosphino)ethyl]phosphine}. Single-crystal Xray crystallography and electrospray ionization mass spectrometry show that the cluster assembly can be formulated as [Au<sub>20sub>(PP>3sub>)>4sub>]Cl>4sub>. The Au<sub>20sub> cluster consists of an icosahedral Au<sub>13sub> core and a seven-Au-atom partial outer shell arranged in a local C<sub>3sub> symmetry. One PP<sub>3sub> ligand coordinates to four Au atoms in the outer shell, while the other three PP<sub>3sub> ligands coordinate to one Au atom from the outer shell and three Au atoms from the surface of the Au<sub>13sub> core, giving rise to an overall chiral 16-electron Au cluster core with C3 symmetry.

Femtosecond pulsed laser ablation of GaAs

International Nuclear Information System (INIS)

Trelenberg, T.W.; Dinh, L.N.; Saw, C.K.; Stuart, B.C.; Balooch, M.

2004-01-01

The properties of femtosecond-pulsed laser deposited GaAs nanoclusters were investigated. Nanoclusters of GaAs were produced by laser ablating a single crystal GaAs target in vacuum or in a buffer gas using a Ti-sapphire laser with a 150 fs minimum pulse length. For in-vacuum deposition, X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) revealed that the average cluster size was approximately 7 nm for laser pulse lengths between 150 fs and 25 ps. The average cluster size dropped to approximately 1.5 nm at a pulse length of 500 ps. It was also observed that film thickness decreased with increasing laser pulse length. A reflective coating, which accumulated on the laser admission window during ablation, reduced the amount of laser energy reaching the target for subsequent laser shots and developed more rapidly at longer pulse lengths. This observation indicates that non-stoichiometric (metallic) ablatants were produced more readily at longer pulse lengths. The angular distribution of ejected material about the target normal was well fitted to a bi-cosine distribution of cos 47 θ+ cos 4 θ for ablation in vacuum using 150 fs pulses. XPS and AES revealed that the vacuum-deposited films contained excess amorphous Ga or As in addition to the stoichiometric GaAs nanocrystals seen with XRD. However, films containing only the GaAs nanocrystals were produced when ablation was carried out in the presence of a buffer gas with a pressure in excess of 6.67 Pa. At buffer gas pressure on the order of 1 Torr, it was found that the stoichiometry of the ablated target was also preserved. These experiments indicate that both laser pulse length and buffer gas pressure play important roles in the formation of multi-element nanocrystals by laser ablation. The effects of gas pressure on the target's morphology and the size of the GaAs nanocrystals formed will also be discussed

Development of subpicosecond pulse radiolysis system

International Nuclear Information System (INIS)

Kozawa, T.; Saeki, A.; Okamoto, K.; Numata, Y.; Kaseda, K.; Yamamoto, T.; Suemine, S.; Yoshida, Y.; Tagawa, S.

2000-01-01

Subpicosecond pulse radiolysis system was developed to elucidate the primary processes of radiation chemistry in the time region of femtosecond. The system consists of a femtosecond electron linac as an irradiation source, a femtosecond laser as an analyzing light and a jitter compensation system which was designed to reduce the effect of jitter between an electron pulse and a laser pulse on the time resolution. The time resolution of 800 fs was achieved. (author)

Fs-laser processing of medical grade polydimethylsiloxane (PDMS)

Energy Technology Data Exchange (ETDEWEB)

Atanasov, P.A., E-mail: paatanas@ie.bas.bg [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784 (Bulgaria); Stankova, N.E.; Nedyalkov, N.N. [Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsaridradsko shose Blvd., Sofia 1784 (Bulgaria); Fukata, N. [International Centre for Materials for NanoArchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1Namiki, Tsukuba 305-0044 (Japan); Hirsch, D.; Rauschenbach, B. [Leibniz Institute of Surface Modification (IOM), Permoserstrasse 15, D-04318 Leipzig (Germany); Amoruso, S.; Wang, X. [Dipartimento di Fisica Università degli Studi di Napoli Federico II and CNR-SPIN, Complesso Universitario di Monte S.Angelo, Via Cintia, I-80126 Napoli (Italy); Kolev, K.N.; Valova, E.I.; Georgieva, J.S.; Armyanov, St.A. [Rostislaw Kaischew Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Block 11, Sofia 1113 (Bulgaria)

2016-06-30

Highlights: • Fs-laser (263, 527 and 1055 nm) processing of PDMS-elastomer is studied. • High quality trenches are produced on the PDMS surface. • The trenches are analyzed by Laser Microscope and by μ-Raman spectrometry. • Selective Ni metallization of the trenches is accomplished via electro-less plating. • The metalized trenches are studied by SEM. - Abstract: Medical grade polydimethylsiloxane (PDMS) elastomer is a biomaterial widely used in medicine and high-tech devices, e.g. MEMS and NEMS. In this work, we report an experimental investigation on femtosecond laser processing of PDMS-elastomer with near infrared (NIR), visible (VIS) and ultraviolet (UV) pulses. High definition trenches are produced by varying processing parameters as laser wavelength, pulse duration, fluence, scanning speed and overlap of the subsequent pulses. The sample surface morphology and chemical composition are investigated by Laser Microscopy, SEM and Raman spectroscopy, addressing the effects of the various processing parameters through comparison with the native materials characteristics. For all the laser pulse wavelengths used, the produced tracks are successfully metalized with Ni via electro-less plating method. We observe a negligible influence of the time interval elapsed between laser treatment and metallization process. Our experimental findings suggest promising perspectives of femtosecond laser pulses in micro- and nano-fabrication of hi-tech PDMS devices.

Achieving few-femtosecond time-sorting at hard X-ray free-electron lasers

Science.gov (United States)

Harmand, M.; Coffee, R.; Bionta, M. R.; Chollet, M.; French, D.; Zhu, D.; Fritz, D. M.; Lemke, H. T.; Medvedev, N.; Ziaja, B.; Toleikis, S.; Cammarata, M.

2013-03-01

Recently, few-femtosecond pulses have become available at hard X-ray free-electron lasers. Coupled with the available sub-10 fs optical pulses, investigations into few-femtosecond dynamics are not far off. However, achieving sufficient synchronization between optical lasers and X-ray pulses continues to be challenging. We report a `measure-and-sort' approach, which achieves sub-10 fs root-mean-squared (r.m.s.) error measurement at hard X-ray FELs, far beyond the 100-200 fs r.m.s. jitter limitations. This timing diagnostic, now routinely available at the Linac Coherent Light Source (LCLS), is based on ultrafast free-carrier generation in optically transparent materials. Correlation between two independent measurements enables unambiguous demonstration of ~6 fs r.m.s. error in reporting the optical/X-ray delay, with single shot error suggesting the possibility of reaching few-femtosecond resolution.

Synthesis and thermoelectric properties of Sb{sub 0.20}CoSb{sub 2.80} skutterudite

Energy Technology Data Exchange (ETDEWEB)

Figueirêdo, C.A., E-mail: camila_fig@hotmail.com [Universidade Federal do Rio Grande do Sul, PGCIMAT, Instituto de Física, 91501-970 Porto Alegre, RS (Brazil); Gallas, M.R. [Universidade Federal do Rio Grande do Sul, PGCIMAT, Instituto de Física, 91501-970 Porto Alegre, RS (Brazil); Institute for Multiscale Simulations, Friedrich-Alexander-Universität, Nägelsbachstrasse 49b, 91052 Erlangen (Germany); Zorzi, J.E. [Universidade de Caxias do Sul, Instituto de Materiais Cerâmicos, 95765-000 Bom Princípio, RS (Brazil); Perottoni, C.A. [Universidade Federal do Rio Grande do Sul, PGCIMAT, Instituto de Física, 91501-970 Porto Alegre, RS (Brazil); Universidade de Caxias do Sul, Instituto de Materiais Cerâmicos, 95765-000 Bom Princípio, RS (Brazil)

2014-06-15

Highlights: • A HP-HT Sb{sub 0.20}CoSb{sub 2.80} phase was prepared by processing cobalt antimonide at 7.7 GPa and 550 °C, for (at least) 5 min. • The mechanism of formation of this phase involves (i) decomposition of cobalt antimonide into CoSb{sub 2} and Sb, and (ii) insertion of Sb into the remaining cobalt antimonide. • The mechanism of formation is qualitatively different from that responsible for the formation of the high pressure (greater than 20 GPa) phase. - Abstract: Polycrystalline samples of cobalt antimonide (CoSb{sub 2.79}) were submitted to different conditions of pressure, temperature and processing time, in a high-pressure toroidal-type chamber, aiming to maximize the production of the high pressure phase previously observed in experiments with a diamond anvil cell. Rietveld refinements of X-ray powder diffraction data were performed to determine the phase composition and structural parameters. The maximum yield, 89(2) wt.% of Sb{sub x}CoSb{sub 3−x} phase, was obtained at 7.7 GPa, 550 °C and (at least) 5 min of processing time. The mechanism behind the formation of Sb{sub x}CoSb{sub 3−x} at high pressure and high temperature is actually not the same as that previously inferred from experiments at higher pressures (20 GPa) and room temperature with the diamond anvil cell. Indeed, evidences suggest that, at high pressure and high temperature, Sb{sub x}CoSb{sub 3−x} is formed by insertion of Sb resulting from decomposition of cobalt antimonide. Thermal conductivity, Seebeck coefficient and electrical conductivity were estimated for CoSb{sub 2.79} and Sb{sub 0.20}CoSb{sub 2.80}. The thermoelectric figure of merit at room temperature for Sb{sub 0.20}CoSb{sub 2.80} resulted 33% greater than that for CoSb{sub 2.79}.

Improving tribological properties of (Zn–Ni)/nano Al{sub 2}O{sub 3} composite coatings produced by ultrasonic assisted pulse plating

Energy Technology Data Exchange (ETDEWEB)

Ataie, Sayed Alireza, E-mail: ataie_s_alireza@metaleng.iust.ac.ir; Zakeri, Alireza

2016-07-25

In this study pulse electroplating was used to deposit the composite coating of (Zn–Ni) strengthened by Al{sub 2}O{sub 3} nanoparticles on mild steel plate. The effect of Al{sub 2}O{sub 3} fraction and ultrasonic irradiation on the properties of the composite coating was also investigated. Scanning electron microscopy and energy dispersive spectroscopy techniques were employed to characterize the morphology and composition of the coating. Topography and surface roughness were investigated by atomic force microscopy. Also in order to evaluate the mechanical properties of the coating micro hardness and wear tests were conducted. It was found that coating hardness was increased from 538 HV to 750 HV and friction coefficient was decreased from 0.588 to 0.392. Results revealed that tribological properties of coating could be improved significantly by using suitable ultrasonic intensity simultaneously with pulse plating. - Highlights: • SEM indicated on the elimination of cracks and pores when ultrasounds were used. • XRD result showed nano sized grains of Zn–Ni matrix was developed in this research. • Simultaneous pulse plating and ultrasonic conditions improved the properties of the coating. • A (Zn–Ni)/nano alumina uniform composite coating for especial applications was developed. • Micro hardness and wear behavior of the coating was modified by intensifying the ultrasound.

Manipulating femtosecond spin-orbit torques with laser pulse sequences to control magnetic memory states and ringing

Science.gov (United States)

Lingos, P. C.; Wang, J.; Perakis, I. E.

2015-05-01

Femtosecond (fs) coherent control of collective order parameters is important for nonequilibrium phase dynamics in correlated materials. Here, we propose such control of ferromagnetic order based on using nonadiabatic optical manipulation of electron-hole (e -h ) photoexcitations to create fs carrier-spin pulses with controllable direction and time profile. These spin pulses are generated due to the time-reversal symmetry breaking arising from nonperturbative spin-orbit and magnetic exchange couplings of coherent photocarriers. By tuning the nonthermal populations of exchange-split, spin-orbit-coupled semiconductor band states, we can excite fs spin-orbit torques that control complex magnetization pathways between multiple magnetic memory states. We calculate the laser-induced fs magnetic anisotropy in the time domain by using density matrix equations of motion rather than the quasiequilibrium free energy. By comparing to pump-probe experiments, we identify a "sudden" out-of-plane magnetization canting displaying fs magnetic hysteresis, which agrees with switchings measured by the static Hall magnetoresistivity. This fs transverse spin-canting switches direction with magnetic state and laser frequency, which distinguishes it from the longitudinal nonlinear optical and demagnetization effects. We propose that sequences of clockwise or counterclockwise fs spin-orbit torques, photoexcited by shaping two-color laser-pulse sequences analogous to multidimensional nuclear magnetic resonance (NMR) spectroscopy, can be used to timely suppress or enhance magnetic ringing and switching rotation in magnetic memories.

Flavour oscillations and CP asymmetry in semileptonic B<sub>s>⁰ decays

Energy Technology Data Exchange (ETDEWEB)

Beale, Steven Thomas [York Univ., Toronto, ON (Canada)

2010-01-01

The B⁰ <sub>s> meson spontaneously transforms into its antiparticle ($\\bar{B}$ ⁰<sub> ssub> ). These ‘flavour oscillations’ occur periodically with a frequency that may be measured. The oscillation frequency is related to the fundamental parameters of the electroweak interaction. Measuring the frequency provides a constraint on the electroweak quark coupling parameter V<sub>ts> and improves the constraint on V<sub>td>. Furthermore, the amplitude of the oscillation process may be slightly different in B⁰ <sub>s> and $\\bar{B}$ ⁰ <sub>s> mesons due to CP violating nature of the weak interaction. This ‘asymmetry’ is expected to be small (a^SM,s <sub>fs> = (2.06 ± 0.57) x 10 ⁵), but may be enhanced (a^s <sub>fs> ≅ O(1%)) by new sources of CP violation. This thesis describes a search for B0 s flavour oscillations and charge asymmetry in the B⁰ <sub>s> → D^- <sub>s> μ⁺v<sub>μ> X (D^- <sub>s> → K^{* 0}K^- ) decay mode using 5.0 fb ^-1 of D0 data. A lower limit is placed on the oscillation frequency, Δm<sub>s> > 9.9 ps ^-1 with an expected sensitivity to oscillations below 14.8 ps ^-1. The charge asymmetry is measured to be a^s <sub>fs> 0.018 ± 0.025(stat) ± 0.002(syst). A combination of these measurements with other decay modes is also presented.

Femtosecond laser ablation of silver foil with single and double pulses

CSIR Research Space (South Africa)

Roberts, DE

2009-01-01

Full Text Available The average ablation depth per pulse of silver foil by 130 fs laser pulses has been measured in vacuum over a range of three orders of magnitude of pulse fluence up to 900 J cm-2. In addition, double pulses with separations up to 3.4 ns have been...

Temporal Airy pulses control cell poration

Directory of Open Access Journals (Sweden)

S. Courvoisier

2016-07-01

Full Text Available We show that spectral phase shaping of fs-laser pulses can be used to optimize laser-cell membrane interactions in water environment. The energy and peak intensity thresholds required for cell poration with single pulse in the nJ range can be significantly reduced (25% reduction in energy and 88% reduction in peak intensity by using temporal Airy pulses, controlled by positive third order dispersion, as compared to bandwidth limited pulses. Temporal Airy pulses are also effective to control the morphology of the induced pores, with prospective applications from cellular to tissue opto-surgery and transfection.

Controllable delay of ultrashort pulses in a quantum dot optical amplifier

DEFF Research Database (Denmark)

Poel, Mike van der; Mørk, Jesper; Hvam, Jørn Märcher

2005-01-01

Optical and electrical tuning of the propagation time of 170 fs pulses in a quantum dot semiconductor amplifier at room temperature is demonstrated. Both pulse slowdown and advancement is possible and we achieve fractional delays (delay divided with pulse duration) of up to 40%. The results...

Electrical behaviors of c-axis textured 0.975Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}–0.025BiCoO{sub 3} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Guo, Feifei [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Yang, Bin, E-mail: binyang@hit.edu.cn [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Zhang, Shantao, E-mail: stzhang@mail.nju.edu.cn [Department of Materials Science and Engineering and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China); Liu, Danqing [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150080 (China); Wu, Fengmin [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Wang, Dali [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150080 (China); Cao, Wenwu [Department of Physics, Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150080 (China); Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States)

2013-10-15

The thin films of 0.975Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}–0.025BiCoO{sub 3} (BNT-BC) have been successfully deposited on (1 1 1) Pt/Ti/SiO{sub 2}/Si (1 0 0) substrates by pulse laser deposition and their ferroelectric, dielectric, local piezoelectric properties and temperature dependent leakage current behaviors have been investigated systematically. X-ray diffraction indicates the films are single phased and c-axis oriented. The thin films exhibit ferroelectric polarization–electric field (P–E) hysteresis loop with a remnant polarization (P{sub r}) of 10.0 μC/cm{sup 2} and an excellent fatigue resistance property up to 5 × 10{sup 9} switching cycles. The dielectric constant and dielectric loss are 500 and 0.22 at 1 kHz, respectively. The tunability of the dielectric constant is about 12% at 20 kV/mm. The piezo-phase response hysteresis loop and piezo-amplitude response butterfly curve are observed by switching spectroscopy mode of piezoelectric force microscope (SS-PFM) and the piezoelectric coefficient d{sub 33} is about 19–63 pm/V, which is comparable to other reports. The dominant leakage current conduction mechanisms are ohmic conduction at low electric field and Schottky emission at high electric field, respectively. Our results may be helpful for further work on BNT-based thin films with improved electric properties.

Optimization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin film by pulsed laser deposition for spin injection

Energy Technology Data Exchange (ETDEWEB)

Jain, Sourabh, E-mail: sourabhjain@ee.iitb.ac.in [Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Sharma, Himanshu [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Kumar Shukla, Amit [Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Tomy, C.V. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Palkar, V.R.; Tulapurkar, Ashwin [Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India)

2014-09-01

We have investigated low temperature magnetic properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) thin films on SrTiO{sub 3} (STO) substrate deposited by pulsed laser deposition (PLD). We observed a large change in the Curie temperature T{sub C} when the LSMO film thickness is reduced from 4 nm (T{sub C}∼280 K) to 2 nm (T{sub C} ∼100 K), which is a result of high strain present at the STO–LSMO interface. The presence of the strain is confirmed by a grazing angle X-ray diffraction (XRD) technique where a particular peak is shifted away from the bulk peak position as we decrease the thickness. In a LSMO/Pb[Zr{sub y}Ti{sub 1−y}]O{sub 3} (PZT)/LSMO magnetic tunnel junction (MTJ), these LSMO thin films can be used for spin injection into the tunnel barrier. Here spin current can be manipulated by changing the strain present at the LSMO–PZT interface by using piezoelectric properties of PZT.

Effects of moderate pump and Stokes chirp on chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering thermometry

KAUST Repository

Gu, Mingming

2018-01-08

The effects of moderate levels of chirp in the pump and Stokes pulses on chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) were investigated. The frequency chirp in the pump and Stokes pulses was introduced by placing SF11 glass disks with thicknesses of 10 mm or 20 mm in the optical path for these beams. The magnitude of the chirp in the probe beam was much greater and was induced by placing a 30-cm rod of SF10 glass in the beam path. The temperature measurements were performed in hydrogen/air non-premixed flames stabilized on a Hencken burner at equivalence ratios of 0.3, 0.5, 0.7, and 1.0. We performed measurements with no disks in pump and Stokes beam paths, and then with disks of 10 mm and 20 mm placed in both beam paths. The spectrum of the nonresonant background four-wave mixing signal narrowed considerably with increasing pump and Stokes chirp, while the resonant CARS signal was relatively unaffected. Consequently, the interference of the nonresonant background with the resonant CARS signal in the frequency-spread dephasing region of the spectrum was minimized. The increased rate of decay of the resonant CARS signal with increasing temperature was thus readily apparent. We have started to analyze the CPP fs CARS thermometry data and initial results indicate improved accuracy and precision are obtained due to moderate chirp in the pump and Stokes laser pulses.

Properties of CoSb{sub 3} films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Christen, H M; Mandrus, D G; Norton, D P; Boatner, L A; Sales, B C

1997-07-01

Polycrystalline CoSb{sub 3} films were grown on a variety of electrically insulating substrates by pulsed laser ablation from a stoichiometric hot-pressed target. These films are fully crystallized in the skutterudite structure, and the grains exhibit a strongly preferred alignment of the cubic [310]-axis perpendicular to the substrate surface. The film quality is studied for different single-crystal substrates and as a function of growth temperature and background gas. Hall measurements show that the films are p-type semiconducting with a room-temperature carrier density of 3 x 10{sup 20} holes/cm{sup 3}. The Hall mobility is found to be 50 to 60 cm{sup 2}/Vs, which is high for such a heavily-doped material. The Seebeck coefficient and the resistivity are measured as a function of temperature and are compared to bulk measurements.

Broadband pump-probe spectroscopy with sub-10-fs resolution for probing ultrafast internal conversion and coherent phonons in carotenoids

International Nuclear Information System (INIS)

Polli, D.; Antognazza, M.R.; Brida, D.; Lanzani, G.; Cerullo, G.; De Silvestri, S.

2008-01-01

We use pump-probe spectroscopy with broadband detection to study electronic energy relaxation and coherent vibrational dynamics in carotenoids. A fast optical multichannel analyzer combined with a non-collinear optical parametric amplifier allows simultaneous acquisition of the differential transmission dynamics on the 500-700 nm wavelength range with sub-10-fs temporal resolution. The broad spectral coverage enables on the one hand a detailed study of the ultrafast bright-to-dark state internal conversion process; on the other hand, the tracking of the motion of the vibrational wavepacket launched on the ground state multidimensional potential energy surface. We present results on all-trans β-carotene and on a long-chain polyene in solution. The developed experimental setup enables the straightforward acquisition and analysis of coherent vibrational dynamics, highlighting time-frequency domain features with extreme resolution

Infrared Observations of FS CMa Stars

Science.gov (United States)

Sitko, Michael L.; Russell, R. W.; Lynch, D. K.; Grady, C. A.; Hammel, H. B.; Beerman, L. C.; Day, A. N.; Huelsman, D.; Rudy, R. J.; Brafford, S. M.; Halbedel, E. M.

2009-01-01

A subset of non-supergiant B[e] stars has recently been recognized as forming a fairly unique class of objects with very strong emission lines, infrared excesses, and locations not associated with star formation. The exact evolutionary state of these stars, named for the prototype FS CMa, is uncertain, and they have often been classified as isolated Herbig AeBe stars. We present infrared observations of two of these stars, HD 45677 (FS CMa), HD 50138 (MWC 158), and the candidate FS CMa star HD 190073 (V1295 Aql) that span over a decade in time. All three exhibit an emission band at 10 microns due to amorphous silicates, confirming that much (if not all) of the infrared excess is due to dust. HD 50138 is found to exhibit 20% variability between 3-13 microns that resembles that found in pre-main sequence systems (HD 163296 and HD 31648). HD 45677, despite large changes at visual wavelengths, has remained relatively stable in the infrared. To date, no significant changes have been observed in HD 190073. This work is supported in part by NASA Origins of Solar Systems grant NAG5-9475, NASA Astrophysics Data Program contract NNH05CD30C, and the Independent Research and Development program at The Aerospace Corporation.

Angular distribution of species in pulsed laser deposition of La{sub x}Ca{sub 1−x}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Ojeda-G-P, Alejandro [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Schneider, Christof W., E-mail: christof.schneider@psi.ch [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Lippert, Thomas; Wokaun, Alexander [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland)

2015-05-01

Highlights: • The angular distribution of species was analyzed for different pressures. • Results show a non-congruent transfer of composition from target to substrate. • Film thickness and composition show different angular distributions. - Abstract: The angular distribution of species from a La{sub 0.4}Ca{sub 0.6}MnO{sub 3} target irradiated with a 248 nm nanosecond pulsed laser was investigated by Rutherford backscattering spectrometry for four different Ar pressures. The film thickness angular distribution was also analyzed using profilometry. Depending on the background gas pressure, the target to substrate distance, and the angular location the film thickness and composition varies considerably. In particular the film composition could vary by up to 17% with respect to the composition of the target material.

Magnetostriction of the polycrystalline Fe{sub 80}Al{sub 20} alloy doped with boron

Energy Technology Data Exchange (ETDEWEB)

Bormio-Nunes, Cristina, E-mail: cristina@demar.eel.usp.br [Escola de Engenharia de Lorena, Dep. de Eng. de Materiais, Universidade de S.Paulo, Lorena, SP (Brazil); Teodoro dos Santos, Claudio; Botani de Souza Dias, Mateus [Escola de Engenharia de Lorena, Dep. de Eng. de Materiais, Universidade de S.Paulo, Lorena, SP (Brazil); Doerr, Mathias; Granovsky, Sergey; Loewenhaupt, Michael [Institut fuer Festkoerperphysik, TU Dresden, D-01062 Dresden (Germany)

2012-10-25

Highlights: Black-Right-Pointing-Pointer Fe{sub 80}Al{sub 20} polycrystalline alloy magnetostriction 40 ppm increased to 80 ppm due to 2% of B doping. Black-Right-Pointing-Pointer B stabilizes {alpha}-FeAl phase and a coexistence of {alpha}-FeAl + Fe{sub 3}Al improves magnetostriction. Black-Right-Pointing-Pointer Presence of Fe{sub 2}B phase causes domain rearrangement revealed by the decrease of the volume magnetostriction. - Abstract: The doping of Fe{sub 80}Al{sub 20} polycrystalline alloy with 2% of boron increased the total magnetostriction twofold compared to a sample without boron. A value close to 80 ppm was achieved at 300 K. The microstructures of the boron-doped alloys show a dendritically solidified matrix with interdendritic {alpha}-FeAl and/or Fe{sub 3}Al and Fe{sub 2}B eutectic between the grains. The XRD analysis reveals an increase in the volume fraction of {alpha}-FeAl and a correspondent decrease of the Fe{sub 3}Al phase volume fraction as the boron content increases. The increase of the volume fraction of this tetragonal Fe{sub 2}B phase in the samples doped with boron causes the decrease of the strong volume magnetostriction that was observed in the alloy without boron. There is some evidence that the improvement of the magnetostriction magnitude due to the addition of boron to the Fe{sub 80}Al{sub 20} alloy could reach the maximal magnetostriction if the 1:1 optimal ratio of the volume fractions of the {alpha}-FeAl and Fe{sub 3}Al phases could be reached.

Transmission of reactive pulsed laser deposited VO{sub 2} films in the THz domain

Energy Technology Data Exchange (ETDEWEB)

Émond, Nicolas; Hendaoui, Ali; Ibrahim, Akram; Al-Naib, Ibraheem; Ozaki, Tsuneyuki; Chaker, Mohamed, E-mail: chaker@emt.inrs.ca

2016-08-30

Highlights: • Synthesis of vanadium dioxide (VO{sub 2}) thin films as a function of oxygen pressure (2–25 mTorr) using Reactive Pulsed Laser Deposition (RPLD). • Characterization of RPLD-grown VO{sub 2} thin films in the THz frequency range. • THz switches and/or sensors require VO{sub 2} films deposited at low oxygen pressure (i.e. low transition temperature, large amplitude contrast of THz transmission, narrow hysteresis width). • THz optical memory applications require VO{sub 2} films deposited at high oxygen pressure (broad hysteresis width). - Abstract: This work reports on the characteristics of the insulator-to-metal transition (IMT) of reactive pulsed laser deposited vanadium dioxide (VO{sub 2}) films in the terahertz (THz) frequency range, namely the transition temperature T{sub IMT}, the amplitude contrast of the THz transmission over the IMT ΔA, the transition sharpness ΔT and the hysteresis width ΔH. XRD analysis shows the sole formation of VO{sub 2} monoclinic structure with an enhancement of (011) preferential orientation when varying the O{sub 2} pressure (P{sub O2}) during the deposition process from 2 to 25 mTorr. THz transmission measurements as a function of temperature reveal that VO{sub 2} films obtained at low P{sub O2} exhibit low T{sub IMT}, large ΔA, and narrow ΔH. Increasing P{sub O2} results in VO{sub 2} films with higher T{sub IMT}, smaller ΔA, broader ΔH and asymmetric hysteresis loop. The good control of the VO{sub 2} IMT features in the THz domain could be further exploited for the development of advanced smart devices, such as ultrafast switches, modulators, memories and sensors.

NMR of the Shastry-Sutherland lattice SrCu{sub 2}(BO{sub 3}){sub 2} in pulsed magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Stern, R. [National Institute of Chemical Physics and Biophysics, 12618 Tallinn (Estonia); Kohlrautz, J.; Haase, J. [Universitaet Leipzig, Faculty of Physics and Earth Sciences, 04103 Leipzig (Germany); Kuehne, H.; Green, E.L.; Wosnitza, J. [Hochfeld-Magnetlabor Dresden (HLD), Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany)

2015-07-01

SrCu{sub 2}(BO{sub 3}){sub 2} is a quasi-two-dimensional spin system consisting of Cu{sup 2+} ions which form orthogonal spin-singlet dimers, also known as the Shastry-Sutherland lattice. This system has been studied extensively using a variety of techniques to probe the spin-triplet excitations, including recent magnetization measurements over 100 T. Spectroscopic techniques, such as nuclear magnetic resonance (NMR), can provide further insight into the spin-coupling mechanisms and excitations. We present {sup 11}B NMR spectra measured in pulsed magnetic fields up to 54 T, and compare those with prior results obtained in static magnetic fields at 41 T. Herewith, we prove the feasibility and efficacy of this technique, yielding the capability for extended studies at highest magnetic fields up to the 100 T regime that determine the spin structure in the 1/3 magnetization plateau and beyond.

Observation of small sub-pulses out of the delayed-interference signal-wavelength converter

DEFF Research Database (Denmark)

Sakaguchi, J.; Nielsen, Mads Lønstrup; Ohira, T.

2005-01-01

The generation of small sub-pulses in the delayed-interference signal-wavelength converter (DISC), which has been studied for use in future 160-Gb/s optical time division multiplexing-wavelength division multiplexing (OTDM-WDM) communication systems, was recently predicted as a potential problem....... In this work, we have experimentally verified the generation of such pulses and its mechanism. In the experiments we used 3.8-ps-long 1.56-mu m input pulses with repetition frequencies from 12.5 to 25.0 GHz and a cross-correlation monitoring system with a time resolution of approximately 2 ps....

Thermal expansion and magnetostriction measurements on PrIr{sub 2}Zn{sub 20}

Energy Technology Data Exchange (ETDEWEB)

Woerl, Andreas; Stingl, Christian; Sakai, Akito; Gegenwart, Philipp [Experimentalphysics VI, Center for Electronic Correlations and Magnetism, University of Augsburg (Germany); Matsumoto, Keisuke T.; Onimaru, Takahiro [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima (Japan); Takabatake, Toshiro [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima (Japan); Institute for Advanced Materials Research, Hiroshima University, Higashi-Hiroshima (Japan)

2016-07-01

Strong hybridization between electric quadrupole moments and conduction electrons gives rise to interesting physical phenomena such as new quantum phases and novel metallic properties. Non-fermi-liquid behavior based on the two channel Kondo effect is predicted by theory. PrIr{sub 2}Zn{sub 20} crystallizes in the CeCr{sub 2}Al{sub 20}-type structure, where the Pr{sup 3+} ions are surrounded by the highly symmetric cubic crystal field of 16 Zn atoms. The ground state is the non-magnetic Γ{sub 3} doublet and carries only electric quadrupole and a magnetic octupole moment. At T{sub Q}=0.11 K the electric quadrupole moments order in a antiferroquadrupolar way. A superconducting transition occurs at T{sub c}=0.05 K. The phase transition at T{sub Q}=0.11 K can be suppressed by high magnetic fields parallel to the [100] direction. We investigate the thermal expansion and magnetostriction at low temperatures. By applying high magnetic fields the system is tuned towards a quadrupolar quantum critical point. Furthermore the reaction of the system on breaking the cubic symmetry by compressive stress is explored.

High power pulse electron beam modification and ion implantation of Hg{sub 1-x}Cd{sub x}Te crystals

Energy Technology Data Exchange (ETDEWEB)

Vojtsekhovskij, A V; Remnev, G E [Tomsk Polytechnic Univ. (Russian Federation). Nuclear Physics Inst.; Opekunov, M S; Kokhanenko, A P; Korotaev, A G; Denisov, Yu A; Oucherenko, D A [Tomsk State Univ. (Russian Federation). Dept. of Radiophysics

1997-12-31

Hg{sub 1-x}Cd{sub x}Te (MCT) samples (x = 0.21 - 0.22) were irradiated by pulse electron beams at doses of 10{sup 13} to 10{sup 17} cm{sup -2}. The electron beams possessed the following parameters: 500 keV electron energy (30-40 A/cm{sup 2} electron current density, 60-80 ns current pulse); 200 keV electron energy (8- 10 A/cm{sup 2} electron current density, 100-200 ns current pulse). The electric conductivity and recombination of modified samples were investigated by the Hall effect and photoconductivity methods. For the 200 keV electron energy beam irradiation, the n-type surface regions were obtained under threshold mechanisms of donor defect generation. For the 500 keV electron energy beam irradiation, the maximum value of charge carrier lifetimes occur in the p- to n-type conductivity conversion range for the initial p-type crystals due to the conductivity compensation. MCT samples (x = 0.21 - 0.22) were implanted with Al ions at doses of 10{sup 12}-10{sup 16} cm{sup -2}. The ion beams possessed the following parameters: (1-10) A/cm{sup 2} ion current density, (100-200) ns current pulse; (150-450) keV Al ion (Al{sup +},Al{sup ++}, Al{sup +++}). The ion distribution and doping profiles were investigated by PIGE and Hall effect methods. Comparison between MCT samples after power pulse ion implantation and after standard ion implantation demonstrates differences in ion distribution, doping profiles and defect formation radiation mechanisms. (author). 3 figs., 8 refs.

Evidence of the semiconductor-metal transition in V{sub 2}O{sub 5} thin films by the pulsed laser photoacoustic method

Energy Technology Data Exchange (ETDEWEB)

Perez-Pacheco, A.; Acosta-Najarro, D. R.; Cruz-Manjarrez, H.; Rodriguez-Fernandez, L.; Pineda-Santamaria, J. C; Aguilar-Franco, M. [Instituto de Fisica-Universidad Nacional Autonoma de Mexico, Mexico DF (Mexico); Castaneda-Guzman, R. [Laboratorio de Fotofisica y Peliculas Delgadas, CCADET-UNAM, Mexico DF (Mexico)

2013-05-14

In this work, the pulsed photoacoustic technique was used to investigate the semiconductor-metal transition of thin vanadium pentoxide films (V{sub 2}O{sub 5}) under increasing temperature. The V{sub 2}O{sub 5} thin films were simultaneously deposited by RF magnetron sputtering at room temperature, on corning glass and SnO{sub 2}:F/glass substrates, in order to compare the photoacoustic response. The elemental and structural analysis of the V{sub 2}O{sub 5} films was performed by Rutherford backscattering spectroscopy and X-ray diffraction. The optical transmission and band gap were determined using UV-Vis spectroscopy. The electrical properties were measured using four-point probe measurements with the Van der Pauw geometry.

New class of compact diode pumped sub 10 fs lasers for biomedical applications

DEFF Research Database (Denmark)

Le, T.; Mueller, A.; Sumpf, B.

2016-01-01

Diode-pumping Ti: sapphire lasers promises a new approach to low-cost femtosecond light sources. Thus in recent years much effort has been taken just to overcome the quite low power and low beam qualities of available green diodes to obtain output powers of several hundred milliwatts from a fs-la...

Development of Cr{sub 3}C{sub 2}-25(Ni20Cr) nanostructured coatings; Desenvolvimento de revestimentos nanostruturados de Cr{sub 3}C{sub 2}-25(Ni20Cr)

Energy Technology Data Exchange (ETDEWEB)

Cunha, Cecilio Alvares da

2012-07-01

This study is divided in two parts. The first part is about the preparation of nanostructured Cr{sub 3}C{sub 2}-25(Ni20Cr) powders by high energy milling followed by characterization of the milled and the as received powder. Analyses of some of the data obtained were done using a theoretical approach. The second part of this study is about the preparation and characterization of coatings prepared with the nanostructured as well as the as received Cr{sub 3}C{sub 2}-25(Ni20Cr) powders. The high temperature erosion-oxidation (E-O) behavior of the coatings prepared with the two types of powders has been compared based on a technological approach. The average crystallite size of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powder decreased rapidly from 145 nm to 50 nm in the initial stages of milling and thereafter decreased slowly to a steady state value of around 10 nm with further increase in milling time. This steady state corresponds to the beginning of a dynamic recovery process. The maximum lattice strain ({epsilon} = 1,17%) was observed in powders milled for 16 hours, and this powders critical crystallite size was 28 nm. In contrast, the lattice parameter attained a minimum for powders milled for 16 hours. Upon reaching the critical crystallite size, the dislocation density attained a steady state regime and all plastic deformation introduced in the material there after was in the form of events occurring at the grain boundaries, due mainly to grain boundary sliding. The deformation energy stored in the crystal lattice of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powders milled for different times was determined from enthalpy variation measurements. These results indicated that the maximum enthalpy variation ({delta}H = 722 mcal) also occurred for powders milled for 16 hours. In a similar manner, the maximum specific heat variation ({delta}C{sub p} = 0,278 cal/gK) occurred for powders milled for 16 hours. The following mechanical properties of Cr{sub 3}C{sub 2}-25(Ni20Cr) coatings

Plasmonic angular tunability of gold nanoparticles generated by fs laser ablation

Energy Technology Data Exchange (ETDEWEB)

Pace, M.L.; Guarnaccio, A.; Ranù, F. [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy); Trucchi, D. [CNR, ISM UOS Montelibretti, Via Salaria km 29.300, Monterotondo Scalo, (RM) 00015 (Italy); Orlando, S., E-mail: stefano.orlando@ism.cnr.it [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy); Mollica, D.; Parisi, G.P. [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy); Medici, L.; Lettino, A. [CNR, IMAA, Area della Ricerca di Potenza -Zona Industriale, Tito Scalo, (PZ) 85050 (Italy); De Bonis, A.; Teghil, R. [Dipart. di Scienze,Università della Basilicata, Viale dell’Ateneo Lucano 10, Potenza, 85100 (Italy); Santagata, A. [CNR, ISM UOS Tito Scalo, Zona Industriale, Tito Scalo (PZ) 85050 (Italy)

2016-06-30

Highlights: • fs pulsed laser ablation as a technique to produce nanoparticles. • Nanoparticle distribution as an evidence for plasmonic tunable resonances. • Correlation between angular distribution of deposited nanoparticles and specific plasmonic resonances. - Abstract: With the aim to study the influence of deposition parameters on the plasmonic properties of gold (Au) nanoparticles (NPs) deposited by ultra-short ablation, we have focused our attention in evaluating how their size distribution can be varied. In this work, the role played by the NPs’ angular distribution, agglomeration and growth is related to the resulting optical properties. UV–vis-NIR absorption spectra together with Scanning Electron Microscopy, Transmission Electron Microscopy and X-ray microdiffraction observations are presented in order to show how the angular distribution of fs laser ablation and deposition of Au NPs provides different plasmonic properties which can be beneficial for several aims, from optoelectronic to biosensor applications.

Application of the ultrashort pulses in bovine dental enamel

International Nuclear Information System (INIS)

Todescan, Carla de Rago

2003-01-01

The interaction of lasers with the hard structures of the teeth, has found the excess of heat as a problem for its utilization. This study analyzes, in vitro, the interaction of the ultrashort pulse laser of Ti:safire (830 nm) with the bovine dental enamel. The system consisted in one main oscillator integrated with an amplifier (CPA). The pulses extracted before the temporal compression inside the amplifier had 30 ps, 1000 Hz and ∼1 mJ. The pulses extracted after the compression had 60 fs, 1000 Hz and ∼0,7 mJ. The M 2 was 1,3, the focal lens 2,5 cm, the focal distance 29,7 and a computerized translation stage x,y,z. We evaluated the amount of tissue removed per pulse,the resulting cavities and the surrounding tissues not irradiated, under OM and SEM. The fluency was the major factor for differentiating the two regimens studied, therefore, the intensity was not so important as we expected in this process. We found: one ablation region in 'cat tongue', one ablation length, one fluency ∼0,7 J/cm 2 for 30 ps and ∼0,5 J/cm 2 for 60 fs (50% of high speed burr), smooth edge for 30 ps and high precision of the sharp edge cut of submicrometric order for 60 fs. (author)

Heat treatment and thickness-dependent electrical study of Se{sub 50}Te{sub 20}S{sub 30} thin film

Energy Technology Data Exchange (ETDEWEB)

Abd-Elrahman, M.I.; Hafiz, M.M.; Qasem, Ammar; Abdel-Rahim, M.A. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt)

2016-08-15

Chalcogenide Se{sub 50}Te{sub 20}S{sub 30} thin film of different thickness was deposited using thermal evaporation technique. The thermogram of the chalcogenide bulk Se{sub 50}Te{sub 20}S{sub 30} was obtained using a differential scanning calorimetry (DSC) with heating rate of 7.5 K/min. The glass transition temperature T{sub g}, crystallization temperature T{sub c} and peak crystallization temperature T{sub p} were identified. The X-ray diffraction (XRD) examination indicates the amorphous nature of the as-deposited film and polycrystalline structure of the thermal annealed ones. The dark electrical resistivity (ρ) measurements were taken in temperature range (300-500 K) and thickness range (200-450 nm). Analysis of the electrical resistivity results revealed two types of conduction mechanisms: conduction due to extended states in the temperature range (T > T{sub c}) and variable range hopping in the temperature range (T < T{sub c}). The effect of the heat treatment and thickness on the density of localized states at the Fermi level N(E{sub F}) and hopping parameters were studied. (orig.)

Broadband spectral shaping in regenerative amplifier based on modified polarization-encoded chirped pulse amplification

Science.gov (United States)

Wang, Xinliang; Lu, Xiaoming; Liu, Yanqi; Xu, Yi; Wang, Cheng; Li, Shuai; Yu, Linpeng; Liu, Xingyan; Liu, Keyang; Xu, Rongjie; Leng, Yuxin

2018-06-01

We present an intra-cavity spectral shaping method to suppress the spectral narrowing in a Ti:sapphire (Ti:Sa) regenerative amplifier. The spectral shaping is realized by manipulating the stored energies of two Ti:Sa crystals with orthogonal c-axes, changing the length of a quartz plate, and rotating a broadband achromatic half-wave plate. Using this method, in our proof-of-concept experiment, an 84-nm-(FWHM)-broadband amplified pulse with an energy gain larger than 106 is obtained, which supports a 17.8 fs Fourier-transform-limited pulse duration. The pulse is compressed to 18.9 fs.

Breaking the Attosecond, Angstrom and TV/m Field Barriers with Ultrafast Electron Beams

International Nuclear Information System (INIS)

Rosenzweig, J. B.; Andonian, G.; Fukasawa, A.; Hemsing, E.; Marcus, G.; Marinelli, A.; Musumeci, P.; O'Shea, B.; O'Shea, F.; Pellegrini, C.; Schiller, D.; Travish, G.; Bucksbaum, P.; Hogan, M.; Krejcik, Patrick; Ferrario, M.; Muggli, Patric

2010-01-01

Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This scheme uses very low charge beams, which may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the Stanford X-ray FEL (LCLS, first of its kind, built with essential UCLA leadership) have produced ∼2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments at UCLA in cryogenic undulator technology, to create compact accelerator/undulator systems that can lase below 0.15 Angst , or be used to permit 1.5 Angst operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications. We discuss the experimental issues associated with this initiative.

A pulse synthesis of beta-FeSi sub 2 layers on silicon implanted with Fe sup + ions

CERN Document Server

Batalov, R I; Terukov, E I; Kudoyarova, V K; Weiser, G; Kuehne, H

2001-01-01

The synthesis of thin beta-FeSi sub 2 films was performed by means of the Fe sup + ion implantation into Si (100) and the following nanosecond pulsed ion treatment of implanted layer. Using the beta-FeSi sub 2 beta-FeSi sub 2 e X-ray diffraction it is shown that the pulsed ion treatment results in the generation of the mixture of two phases: FeSi and beta-FeSi sub 2 with stressed crystal lattices. The following short-time annealing leads to the total transformation of the FeSi phase into the beta-FeSi sub 2 one. The Raman scattering data prove the generation of the beta-FeSi sub 2 at the high degree of the silicon crystallinity. The experimental results of the optical absorption testify to the formation of beta-FeSi sub 2 layers and precipitates with the straight-band structure. The photoluminescence signal at lambda approx = 1.56 mu m observes up to 210 K

EST Table: FS733278 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS733278 E_FL_bmmt_20O16_F_0 10/09/28 77 %/113 aa ref|XP_974421.1| PREDICTED: similar to synoviolin.../09/10 70 %/106 aa gnl|Amel|GB14313-PA 10/09/10 77 %/113 aa gi|91087035|ref|XP_974421.1| PREDICTED: similar to synoviolin [Tribolium castaneum] DC547331 bmmt ...

An ultra short pulse reconstruction software applied to the GEMINI high power laser system

Energy Technology Data Exchange (ETDEWEB)

Galletti, Mario, E-mail: mario.gall22@gmail.com [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Galimberti, Marco [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Hooker, Chris [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); University of Oxford, Oxford (United Kingdom); Chekhlov, Oleg; Tang, Yunxin [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Bisesto, Fabrizio Giuseppe [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Curcio, Alessandro [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Sapienza – University of Rome, P.le Aldo Moro, 2, 00185 Rome (Italy); Anania, Maria Pia [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Giulietti, Danilo [Physics Department of the University and INFN, Pisa (Italy)

2016-09-01

The GRENOUILLE traces of Gemini pulses (15 J, 30 fs, PW, shot per 20 s) were acquired in the Gemini Target Area PetaWatt at the Central Laser Facility (CLF), Rutherford Appleton Laboratory (RAL). A comparison between the characterizations of the laser pulse parameters made using two different types of algorithms: Video Frog and GRenouille/FrOG (GROG), was made. The temporal and spectral parameters came out to be in great agreement for the two kinds of algorithms. In this experimental campaign it has been showed how GROG, the developed algorithm, works as well as VideoFrog algorithm with the PetaWatt pulse class. - Highlights: • Integration of the diagnostic tool on high power laser. • Validation of the GROG algorithm in comparison to a well-known commercial available software. • Complete characterization of the GEMINI ultra-short high power laser pulse.

Epitaxial thin-film growth of Ruddlesden-Popper-type Ba{sub 3}Zr{sub 2}O{sub 7} from a BaZrO{sub 3} target by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina [University of Engineering and Technology, Laser and Optronics Centre, Department of Physics, Lahore (Pakistan); Awan, M.S. [Ibn-e-Sina Institute of Science and Technology (ISIT), Islamabad (Pakistan); Bashir, Shazia [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Iqbal, Nida [Universiti Teknologi Malaysia, Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Johor Bahru, Johor (Malaysia)

2016-07-15

Ruddlesden-Popper Ba{sub 3}Zr{sub 2}O{sub 7} thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba{sub 3}Zr{sub 2}O{sub 7} phase from BaZrO{sub 3} target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba{sub 3}Zr{sub 2}O{sub 7} thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba{sub 3}Zr{sub 2}O{sub 7} phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba{sub 3}Zr{sub 2}O{sub 7} Ruddlesden-Popper-type perovskite structure. (orig.)

Structural comparison between La{sub 0.60}Y{sub 0.07}Ca{sub 0.33}MnO{sub 3-{delta}} bulk and pulsed laser deposited thin films

Energy Technology Data Exchange (ETDEWEB)

Teodorescu, V.S. E-mail: teoval@alpha1.infim.ro; Nistor, L.C.; Valeanu, M.; Ghica, C.; Sandu, C.; Mihailescu, I.N.; Ristoscu, C.; Deville, J.P.; Werckmann, J

2000-03-01

This work is a comparative study of the structural and magneto-transport properties of La{sub 0.60}Y{sub 0.07}Ca{sub 0.33}MnO{sub 3-{delta}} (LYCMO) as bulk and thin film. The bulk samples were prepared by solid-state reaction between the corresponding metallic oxides mixed in stoichiometric ratios. The thin film was deposited by pulsed laser deposition on an MgO single crystal using an excimer laser. We show that the structure and stoichiometry of the bulk target are perfectly reproduced in the thin film. We measured the magnetoresistive effect on both the LYCMO pellet and the thin film by using the four-probe technique. The maximum of the MR effect is 680% on the polycrystalline thin film in a 2 T magnetic field.

Growth of LiMn{sub 2}O{sub 4} thin films by pulsed-laser deposition and their electrochemical properties in lithium microbatteries

Energy Technology Data Exchange (ETDEWEB)

Julien, C. [Univ. Pierre et Marie Curie, Paris (France). LMDH; Haro-Poniatowski, E. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico); Camacho-Lopez, M.A. [LMDH, UMR 7603, Universite Pierre et Marie Curie, 4 place Jussieu, 75252, Paris (France); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico (Mexico); Jimenez-Jarquin, J. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico)

2000-03-01

Films of LiMn{sub 2}O{sub 4} were grown by pulsed-laser deposition (PLD) onto silicon wafers using sintered targets which consisted in the mixture of LiMn{sub 2}O{sub 4} and Li{sub 2}O powders. The film formation has been studied as a function of the preparation conditions, i.e. composition of the target, substrate temperature, and oxygen partial pressure in the deposition chamber. Composition, morphology and structural properties of PLD films have been investigated using Rutherford backscattering spectroscopy, scanning electron microscopy, X-ray diffraction and Raman scattering spectroscopy. The films deposited from target LiMn{sub 2}O{sub 4}+15% Li{sub 2}O have an excellent crystallinity when deposited onto silicon substrate maintained at 300 C in an oxygen partial pressure of 100 mTorr. It is found that such a film crystallizes in the spinel structure (Fd3m symmetry) as evidenced by X-ray diffraction. Well-textured polycrystalline films exhibit crystallite size of 300 nm. Pulsed-laser deposited LiMn{sub 2}O{sub 4} thin films obtained with a polycrystalline morphology were successfully used as cathode materials in lithium microbatteries. The Li//LiMn{sub 2}O{sub 4} thin film cells have been tested by cyclic voltammetry and galvanostatic charge-discharge techniques in the potential range 3.0-4.2 V. Specific capacity as high as 120 mC/cm{sup 2} {mu}m was measured on polycrystalline films. The chemical diffusion coefficients for the Li{sub x}Mn{sub 2}O{sub 4} thin films appear to be in the range of 10{sup -11}-10{sup -12} cm{sup 2}/s. Electrochemical measurements show a good cycleability of PLD films when cells are charged-discharged at current densities of 5-25 {mu}A/cm{sup 2}. (orig.)

Growth and annealing effect of SrTiO{sub 3} thin films grown by pulsed laser deposition using fourth harmonic Nd:YAG pulsed laser

Energy Technology Data Exchange (ETDEWEB)

Takamura, Koji; Fujiwara, Takumi; Yokota, Akinobu; Nakamura, Motonori; Yoshimoto, Ken' ichi [National Institute of Technology, Asahikawa College, 2-2-1-6 Shunkodai, Asahikawa 071-8142 (Japan)

2017-06-15

SrTiO{sub 3} homoepitaxial films were grown by pulsed laser deposition (PLD) using a fourth harmonic Nd:YAG pulsed laser. The substrate temperature was kept constant at 600, 700, or 800 C. The laser energy was set at 9-25 mJ on the polycrystal SrTiO{sub 3} target. Post-procedure annealing was performed in the air for 24 h. The X-ray diffraction measurement results showed that the lattice constant of the film was only 0.010 Aa larger than that of the substrate and was not dependent on the annealing temperature. We demonstrated the possibility of growing near-stoichiometric SrTiO{sub 3} film by PLD using an Nd:YAG laser. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Pulse shape discrimination properties of Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B single crystal in comparison with CsI:Tl

Energy Technology Data Exchange (ETDEWEB)

Rawat, S. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Tyagi, Mohit [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Netrakanti, P.K.; Kashyap, V.K.S.; Mitra, A. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Singh, A.K.; Desai, D.G. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kumar, G. Anil [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Gadkari, S.C. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2016-12-21

Single crystals of Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B and CsI:Tl were grown by Czochralski and Bridgman techniques, respectively. While both the crystals exhibited similar emission at about 550 nm, their scintillation decay times showed significantly different characteristics. The average scintillation decay time of Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B crystal was found to be about 284 ns for alpha excitation compared to 108 ns measured for a gamma source. On the other hand in CsI:Tl crystals, the alpha excitation resulted in a lower average decay time of 600 ns compared to 1200 ns with gamma excitation. Their pulse shape discrimination (PSD) for gamma and alpha radiations were studied by coupling the scintillators with photomultiplier tube or SiPM and employing an advanced digitizer as well as a conventional zero-crossing setup. In spite of having a poor α/γ light yield ratio, the PSD figure of merit and the difference of zero-crossing time in Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:Ce,B crystals were found to be superior in comparison to CsI:Tl crystals.

Generation of MoS{sub 2} quantum dots by laser ablation of MoS{sub 2} particles in suspension and their photocatalytic activity for H{sub 2} generation

Energy Technology Data Exchange (ETDEWEB)

Baldoví, Herme G.; Latorre-Sánchez, Marcos; Esteve-Adell, Iván [Universitat Politècnica de València, Instituto Universitario de Tecnología Química CSIC-UPV and Departamento de Química (Spain); Khan, Anish; Asiri, Abdullah M. [King Abdulaziz University, Center of Excellence for Advanced Materials Research (Saudi Arabia); Kosa, Samia A. [King Abdulaziz University, Chemistry Department, Faculty of Science (Saudi Arabia); Garcia, Hermenegildo, E-mail: hgarcia@qim.upv.es [Universitat Politècnica de València, Instituto Universitario de Tecnología Química CSIC-UPV and Departamento de Química (Spain)

2016-08-15

MoS{sub 2} quantum dots (QDs) have been obtained in colloidal suspensions by 532 nm laser ablation (7 ns fwhp/pulse, 50 mJ/pulse) of commercial MoS{sub 2} particles in acetonitrile. High-resolution transmission electron microscopy images show a lateral size distribution from 5 to 20 nm, but a more homogeneous particle size of 20 nm can be obtained by silica gel chromatography purification in acetonitrile. MoS{sub 2} QDs obtained by laser ablation are constituted by 3–6 MoS{sub 2} layers (1.8–4 nm thickness) and exhibit photoluminescence whose λ{sub PL} varies from 430 to 530 nm depending on the excitation wavelength. As predicted by theory, the confinement effect and the larger periphery in MoS{sub 2} QDs increasing the bandgap and having catalytically active edges are reflected in an enhancement of the photocatalytic activity for H{sub 2} generation upon UV–Vis irradiation using CH{sub 3}OH as sacrificial electron donor due to the increase in the reduction potential of conduction band electrons and the electron transfer kinetics.

Femtosecond resolution timing jitter correction on a TW scale Ti:sapphire laser system for FEL pump-probe experiments.

Science.gov (United States)

Csatari Divall, Marta; Mutter, Patrick; Divall, Edwin J; Hauri, Christoph P

2015-11-16

Intense ultrashort pulse lasers are used for fs resolution pump-probe experiments more and more at large scale facilities, such as free electron lasers (FEL). Measurement of the arrival time of the laser pulses and stabilization to the machine or other sub-systems on the target, is crucial for high time-resolution measurements. In this work we report on a single shot, spectrally resolved, non-collinear cross-correlator with sub-fs resolution. With a feedback applied we keep the output of the TW class Ti:sapphire amplifier chain in time with the seed oscillator to ~3 fs RMS level for several hours. This is well below the typical pulse duration used at FELs and supports fs resolution pump-probe experiments. Short term jitter and long term timing drift measurements are presented. Applicability to other wavelengths and integration into the timing infrastructure of the FEL are also covered to show the full potential of the device.

Energetic mid-IR femtosecond pulse generation by self-defocusing soliton-induced dispersive waves in a bulk quadratic nonlinear crystal

DEFF Research Database (Denmark)

Zhou, Binbin; Guo, Hairun; Bache, Morten

2015-01-01

Generating energetic femtosecond mid-IR pulses is crucial for ultrafast spectroscopy, and currently relies on parametric processes that, while efficient, are also complex. Here we experimentally show a simple alternative that uses a single pump wavelength without any pump synchronization and with...... by using large-aperture crystals. The technique can readily be implemented with other crystals and laser wavelengths, and can therefore potentially replace current ultrafast frequency-conversion processes to the mid-IR....... and without critical phase-matching requirements. Pumping a bulk quadratic nonlinear crystal (unpoled LiNbO3 cut for noncritical phase-mismatched interaction) with sub-mJ near-IR 50-fs pulses, tunable and broadband (∼ 1,000 cm−1) mid-IR pulses around 3.0 μm are generated with excellent spatio-temporal pulse...... quality, having up to 10.5 μJ energy (6.3% conversion). The mid-IR pulses are dispersive waves phase-matched to near-IR self-defocusing solitons created by the induced self-defocusing cascaded nonlinearity. This process is filament-free and the input pulse energy can therefore be scaled arbitrarily...

Roughness generation during Si etching in Cl{sub 2} pulsed plasma

Energy Technology Data Exchange (ETDEWEB)

Mourey, Odile; Petit-Etienne, Camille; Cunge, Gilles, E-mail: gilles.cunge@cea.fr; Darnon, Maxime; Despiau-Pujo, Emilie; Brichon, Paulin; Lattu-Romain, Eddy; Pons, Michel; Joubert, Olivier [Univ. Grenoble Alpes, CNRS, CEA-Leti Minatec, LTM, F-38054 Grenoble Cedex (France)

2016-07-15

Pulsed plasmas are promising candidates to go beyond limitations of continuous waves' plasma. However, their interaction with surfaces remains poorly understood. The authors investigated the silicon etching mechanism in inductively coupled plasma (ICP) Cl{sub 2} operated either in an ICP-pulsed mode or in a bias-pulsed mode (in which only the bias power is pulsed). The authors observed systematically the development of an important surface roughness at a low duty cycle. By using plasma diagnostics, they show that the roughness is correlated to an anomalously large (Cl atoms flux)/(energetic ion flux) ratio in the pulsed mode. The rational is that the Cl atom flux is not modulated on the timescale of the plasma pulses although the ion fluxes and energy are modulated. As a result, a very strong surface chlorination occurs during the OFF period when the surface is not exposed to energetic ions. Therefore, each energetic ion in the ON period will bombard a heavily chlorinated silicon surface, leading to anomalously high etching yield. In the ICP pulsed mode (in which the ion energy is high), the authors report yields as high as 40, which mean that each individual ion impacts will generate a “crater” of about 2 nm depth at the surface. Since the ion flux is very small in the pulsed ICP mode, this process is stochastic and is responsible for the roughness initiation. The roughness expansion can then be attributed partly to the ion channeling effect and is probably enhanced by the formation of a SiClx reactive layer with nonhomogeneous thickness over the topography of the surface. This phenomenon could be a serious limitation of pulsed plasma processes.

Possibility of gas sensor based on C{sub 20} molecular devices

Energy Technology Data Exchange (ETDEWEB)

Zhao, Wenkai [School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 (China); Yang, Chuanlu, E-mail: yangchuanlu@126.com [School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 (China); Zou, Dongqing [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Sun, Zhaopeng [School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025 (China); Ji, Guomin [Electrical and Computer Engineering, The University of Oklahoma, Norman, Tulsa, OK 74078 (United States)

2017-06-09

We theoretically investigate the possibility of diatomic gas detection (NO, CO, O{sub 2}) by making use of the transport properties of the C{sub 20} molecular junctions. The calculations are performed by using nonequilibrium Green's function (NEGF) formalism in combination with density functional theory (DFT). In this work, we systematically study the most stable adsorption structural configurations, adsorption energy, and the transport properties on C{sub 20} molecular junctions with these diatomic gas molecules. It is found that NO and O{sub 2} gas molecule can be detected selectively. We suggest its possibility of nanosensors for highly sensitive and selective based on C{sub 20} molecular junction systems. - Highlights: • The most favorable adsorption site is investigated. • The mechanism of gas sensors is revealed. • NO and O{sub 2} gas molecules can be detected by C{sub 20} selectively.

Detection of carbon monoxide (CO) in sooting hydrocarbon flames using femtosecond two-photon laser-induced fluorescence (fs-TPLIF)

Science.gov (United States)

Wang, Yejun; Kulatilaka, Waruna D.

2018-01-01

Ultrashort-pulse, femtosecond (fs)-duration, two-photon laser-induced fluorescence (fs-TPLIF) measurements of carbon monoxide (CO) are reported in rich, sooting hydrocarbon flames. CO-TPLIF detection using conventional nanosecond or picosecond lasers are often plagued by photochemical interferences, specifically under fuel-rich flames conditions. In the current study, we investigate the commonly used CO two-photon excitation scheme of the B1Σ+ ← X1Σ+ electronic transition, using approximately 100-fs-duration excitation pulses. Fluorescence emission was observed in the Ångström band originating from directly populated B1Σ+ upper state, as well as, in the third positive band from collisionally populated b3Σ+ upper state. The current work was focused on the Ångström band emission. Interference from nascent C2 emissions originating from hot soot particles in the flame could be reduced to a negligible level using a narrower detection gate width. In contrast, avoiding interferences from laser-generated C2 Swan-band emissions required specific narrowband spectral filtering in sooting flame conditions. The observed less than quadratic laser pulse energy dependence of the TPLIF signal suggests the presence of strong three-photon ionization and stimulated emission processes. In a range of CH4/air and C2H4/air premixed flames investigated, the measured CO fluorescence signals agree well with the calculated equilibrium CO number densities. Reduced-interference CO-TPLIF imaging in premixed C2H4/O2/N2 jet flames is also reported.

Study of the ionization of H{sup +}{sub 2} ions in strong laser fields; Untersuchung der Ionisation von H{sup +}{sub 2}-Ionen in starken Laserfeldern

Energy Technology Data Exchange (ETDEWEB)

Odenweller, Matthias

2010-07-01

In the framework of this thesis it has been succeeded to develop a worldwide unique measurement apparatur, by which hydrogen-molecule ions can be ionized by means of short laser pulses and the reaction product kinematically completely measured. For this a detection method following the Coltrims technique, in which both protons and electrons can be detected over the complete spatial angle. The H{sup +}{sub 2} ions origin from a high-frequency ion source and are accelerated to 400 keV. This ion beam is overlapped with a 780-nm laser pulse othe pulse length 40 fs. After the reaction the molecule ions fragments either via the dissociation channel H{sup +}{sub 2}+nh{nu}{yields}H+H{sup +} or via an ionization followed by a Coulomb explosion: H{sup +}{sub 2}+nh{nu}{yields}H{sup +}+H{sup +}+e{sup -}. The projectiles are detected after a drift path of about 3 m on an ion detector. For the detection of the electrons a special spectrometer was concipated. In the reaction it comes by the comparatively long pulse length already at low intensities to dissociation processes. The dissociating molecule reaches still during the increasing side of the laser pulse in this way distances, in which the charge-resonance-enhanced-ionization (CREI) can take place. Also the angular distribution of the measured protons lying in a very small angular range around the polarization direction of the laser suggests that CREI is the dominant ionization process. At circular polarization however a netto-acceleration of the electrons perpendicularly to the direction of the electric field at the ionization time takes place, so that the measurement of the electron momenta represents a suited measurement quantity for the study of the ionization process. By this way angular distributions of the electrons relatively to the internuclear axis within the polarization plane could be measured.

Ultrawide spectral broadening and compression of single extremely short pulses in the visible, uv-vuv, and middle infrared by high-order stimulated Raman scattering

International Nuclear Information System (INIS)

Kalosha, V. P.; Herrmann, J.

2003-01-01

We present the results of a comprehensive analytical and numerical study of ultrawide spectral broadening and compression of isolated extremely short visible, uv-vuv and middle infrared (MIR) pulses by high-order stimulated Raman scattering in hollow waveguides. Spectral and temporal characteristics of the output pulses and the mechanism of pulse compression using dispersion of the gas filling and output glass window are investigated without the slowly varying envelope approximation. Physical limitations due to phase mismatch, velocity walk off, and pump-pulse depletion as well as improvements through the use of pump-pulse sequences and dispersion control are studied. It is shown that phase-locked pulses as short as ∼2 fs in the visible and uv-vuv, and 6.5 fs in the MIR can be generated by coherent scattering in impulsively excited Raman media without the necessity of external phase control. Using pump-pulse sequences, shortest durations in the range of about 1 fs for visible and uv-vuv probe pulses are predicted

Extension of supercontinuum spectrum generated in photonic crystal fiber by using chirped femtosecond pulses

Science.gov (United States)

Vengelis, Julius; Jarutis, Vygandas; Sirutkaitis, Valdas

2017-08-01

We present results of experimental and numerical investigation of supercontinuum generation in polarization maintaining photonic crystal fiber (PCF) using chirped femtosecond pulses. The initial unchirped pump pulse source was a mode-locked Yb:KGW laser generating 52 nJ energy 110 fs duration pulses at 1030 nm with 76 MHz repetition rate. The nonlinear medium was a 32 cm long polarization maintaining PCF manufactured by NKT Photonics A/S. We demonstrated the influence of pump pulse chirp on spectral characteristics of supercontinuum. We showed that by chirping pump pulses positively or negatively one can obtain broader supercontinuum spectrum than in case of unchirped pump pulses at the same peak power. Moreover, the extension can be controlled by changing the amount of pump pulse chirp. In our case the supercontinuum spectrum width was extended by up to 115 nm (at maximum chirp value of +10500 fs2 that we could achieve in our setup) compared to the case of unchirped pump at the same peak power.

Time-resolved investigations of the fragmentation dynamic of H2 (D2) in and with ultra-short laser pulses

International Nuclear Information System (INIS)

Ergler, T.

2006-01-01

In course of this work pump-probe experiments aimed to study ultrafast nuclear motion in H 2 (D 2 ) fragmentation by intense 6-25 fs laser pulses have been carried out. In order to perform time-resolved measurements, a Mach-Zehnder interferometer providing two identical synchronized laser pulses with the time-delay variable from 0 to 3000 fs with 300 as accuracy and long-term stability has been built. The laser pulses at the intensities of up to 10 15 W/cm 2 were focused onto a H 2 (D 2 ) molecular beam leading to the ionization or dissociation of the molecules, and the momenta of all charged reactions fragments were measured with a reaction microscope. With 6-7 fs pulses it was possible to probe the time evolution of the bound H + 2 (D + 2 ) nuclear wave packet created by the first (pump) laser pulse, fragmenting the molecule with the second (probe) pulse. A fast delocalization, or ''collapse'', and subsequent ''revival'' of the vibrational wave packet have been observed. In addition, the signatures of the ground state vibrational excitation in neutral D 2 molecule have been found, and the dominance of a new, purely quantum mechanical wave packet preparation mechanism (the so-called ''Lochfrass'') has been proved. In the experiments with 25 fs pulses the theoretically predicted enhancement of the ionization probability for the dissociating H + 2 molecular ion at large internuclear distances has been detected for the first time. (orig.)

Abrupt symmetry decrease in the ThT{sub 2}Al{sub 20} alloys (T = 3d transition metal)

Energy Technology Data Exchange (ETDEWEB)

Uziel, A.; Bram, A.I. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 8410501 (Israel); Venkert, A. [Nuclear Research Center-Negev, POB 9001, Beer-Sheva (Israel); Kiv, A.E.; Fuks, D. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501 (Israel); Meshi, L., E-mail: louisa@bgu.ac.il [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501 (Israel); Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva, 8410501 (Israel)

2015-11-05

Th-T-Al system, where T-3d transition metals, was studied at ThT{sub 2}Al{sub 20} stoichiometry to establish the influence of T on the structural stability of ternary aluminide formed. Different alloys were prepared, varying T in the row from Ti to Fe. Using electron microscopy and X-ray diffraction methods it was found that ThT{sub 2}Al{sub 20} phase adopts CeCr{sub 2}Al{sub 20} structure type when T = Ti, V, and Cr. Starting from Mn, the symmetry of the stable Al-rich phase, which forms in the alloys with the same composition, decreases from cubic to orthorhombic. The results of Density Functional Theory (DFT) calculations coincide with experiments. Concepts of the Theory of Coordination Compounds and Jahn–Teller effect were used to explain the observed abrupt change of the symmetry. These considerations were supported by DFT calculations. - Highlights: • Type of transition metal influences symmetry change in the ThT{sub 2}Al{sub 20} alloys. • It was found that cubic ThT{sub 2}Al{sub 20} phase is stable for T = Ti, V and Cr. • When T = Mn, Fe–Al + orthorhombic ThT{sub 2}Al{sub 10} are formed, lowering the symmetry. • Experimental results and DFT calculations were in full agreement. • TCC and of Jahn–Teller effect were used for explanation of the results.

Compact sub-nanosecond pulse seed source with diode laser driven by a high-speed circuit

Science.gov (United States)

Wang, Xiaoqian; Wang, Bo; Wang, Junhua; Cheng, Wenyong

2018-06-01

A compact sub-nanosecond pulse seed source with 1550 nm diode laser (DL) was obtained by employing a high-speed circuit. The circuit mainly consisted of a short pulse generator and a short pulse driver. The short pulse generator, making up of a complex programmable logic device (CPLD), a level translator, two programmable delay chips and an AND gate chip, output a triggering signal to control metal-oxide-semiconductor field-effect transistor (MOSFET) switch of the short pulse driver. The MOSFET switch with fast rising time and falling time both shorter than 1 ns drove the DL to emit short optical pulses. Performances of the pulse seed source were tested. The results showed that continuously adjustable repetition frequency ranging from 500 kHz to 100 MHz and pulse duration in the range of 538 ps to 10 ns were obtained, respectively. 537 μW output was obtained at the highest repetition frequency of 100 MHz with the shortest pulse duration of 538 ps. These seed pulses were injected into an fiber amplifier, and no optical pulse distortions were found.

Time-resolved plasma spectroscopy of thin foils heated by a relativistic-intensity short-pulse laser

International Nuclear Information System (INIS)

Audebert, P.; Gauthier, J.-C.; Shepherd, R.; Fournier, K.B.; Price, D.; Lee, R.W.; Springer, P.; Peyrusse, O.; Klein, L.

2002-01-01

Time-resolved K-shell x-ray spectra are recorded from sub-100 nm aluminum foils irradiated by 150-fs laser pulses at relativistic intensities of Iλ 2 =2x10 18 W μm 2 /cm 2 . The thermal penetration depth is greater than the foil thickness in these targets so that uniform heating takes place at constant density before hydrodynamic motion occurs. The high-contrast, high-intensity laser pulse, broad spectral band, and short time resolution utilized in this experiment permit a simplified interpretation of the dynamical evolution of the radiating matter. The observed spectrum displays two distinct phases. At early time, ≤500 fs after detecting target emission, a broad quasicontinuous spectral feature with strong satellite emission from multiply excited levels is seen. At a later time, the He-like resonance line emission is dominant. The time-integrated data is in accord with previous studies with time resolution greater than 1 ps. The early time satellite emission is shown to be a signature of an initial large area, high density, low-temperature plasma created in the foil by fast electrons accelerated by the intense radiation field in the laser spot. We conclude that, because of this early time phenomenon and contrary to previous predictions, a short, high-intensity laser pulse incident on a thin foil does not create a uniform hot and dense plasma. The heating mechanism has been studied as a function of foil thickness, laser pulse length, and intensity. In addition, the spectra are found to be in broad agreement with a hydrodynamic expansion code postprocessed by a collisional-radiative model based on superconfiguration average rates and on the unresolved transition array formalism

Controllable nonlocal behaviour by cascaded second-harmonic generation of fs pulses

DEFF Research Database (Denmark)

Bache, Morten; Bang, Ole; Krolikowski, Wieslaw

2008-01-01

Second-harmonic generation (SHG) of ultra-short pulses can act as a prototypical nonlocal nonlinear model, since the strength and nature of the temporal nonlocality can be controlled through the phase-mismatch parameter. The presence of a group-velocity mismatch namely implies that when the phase...... mismatch is small the nonlocal response function becomes oscillatory, while for large phase mismatch it becomes localized. In the transition between the two regimes the strength of the nonlocality diverges, and the system goes from a weakly nonlocal to a strongly nonlocal state. When simulating soliton...... compression to few-cycle pulses in the cascaded quadratic soliton compressor, the spectral content of the full coupled SHG model is predicted by the nonlocal model even when few-cycle pulses are interacting....

Calibration of SeaWiFS after two years on orbit

Science.gov (United States)

Barnes, Robert A.; McClain, Charles R.

1999-12-01

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) was launched on 1 August 1997, and the first Earth images were taken on 4 September 1997. Regular, daily measurements of the sun, via the onboard diffuser, started on 9 September 1997 and regular, monthly measurements of the moon on November 14, 1997. These lunar measurements, as first reported at EUROPTO'98, provide a highly sensitive method for determining the change in the radiometric sensitivity of SeaWiFS. The prelaunch radiometric calibration used by SeaWiFS was performed in the Spring of 1997 at the spacecraft manufacturer's facility. The calibration measurements were made by a team from the National Institute of Standards and Technology (NIST) and the SeaWiFS Project. The uncertainties in this calibration range from 2% to 3% for the eight SeaWiFS bands. In addition, a set of outdoor measurements of the sun were made at the instrument manufacturer's facility in November 1993, just before the delivery of SeaWiFS to the spacecraft manufacturer. These solar measurements, using the instrument's diffuser, were combined with a separate set of solar radiometer measurements to determine the transmittance of the atmosphere. At the start of on-orbit measurements by SeaWiFS, solar measurements were made again by the instrument. These two sets of measurements make up the transfer-to-orbit experiment. From the ground measurements, the outputs of the SeaWiFS bands on orbit were predicted. For each band, the output from the initial on-orbit measurements agree with the predicted values by 21/2% or less. The uncertainties for the transfer-to-orbit experiment are estimated to be approximately 3% to 4%. From 14 November 1997 to 29 June 1999, SeaWiFS has made 20 measurements of the moon. The analysis of lunar measurements presented here has minor modifications to that presented at EUROPTO'98. The trend lines from the current analysis have been extrapolated back from 14 November 1997 to 4 September 1997 to describe the changes

408-fs SESAM mode locked Cr:ZnSe laser

Science.gov (United States)

Bu, Xiangbao; Shi, Yuhang; Xu, Jia; Li, Huijuan; Wang, Pu

2018-01-01

We report self-starting femtosecond operation of a 127-MHz SESAM mode locked Cr:ZnSe laser around 2420 nm. A thulium doped double clad fiber laser at 1908 nm was used as the pumping source. In the normal dispersion regime, stable pulse pairs with constant phase differences in the multipulse regime were observed. The maximum output power was 342 mW with respect to incident pump power of 4.8 W and the corresponding slope efficiency was 10.4%. By inserting a piece of sapphire plate, dispersion compensation was achieved and the intra-cavity dispersion was moved to the anomalous regime. A maximum output power of 403 mW was obtained and the corresponding slope efficiency was 12.2%. Pulse width was measured to be 408 fs by a collinear autocorrelator using two-photon absorption in an InGaAs photodiode. The laser spectrum in multipulse operation showed a clear periodic modulation.

Bulk and surface electron transport in topological insulator candidate YbB{sub 6-δ}

Energy Technology Data Exchange (ETDEWEB)

Glushkov, Vladimir V.; Demishev, Sergey V.; Sluchanko, Nikolay E. [Prokhorov General Physics Institute of RAS, Vavilov str. 38, 119991, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Institutskii per. 9, 141700, Dolgoprudny, Moscow Region (Russian Federation); Bozhko, Alexey D.; Bogach, Alexey V.; Semeno, Alexey V.; Voronov, Valeriy V. [Prokhorov General Physics Institute of RAS, Vavilov str. 38, 119991, Moscow (Russian Federation); Dukhnenko, Anatoliy V.; Filipov, Volodimir B.; Shitsevalova, Natalya Yu. [Frantsevich Institute for Problems of Materials Science NAS, Krzhyzhanovsky str. 3, 03680, Kiev (Ukraine); Kondrin, Mikhail V. [Vereshchagin Institute of High Pressure Physics of RAS, 142190, Troitsk, Moscow (Russian Federation); Kuznetsov, Alexey V.; Sannikov, Ilia I. [National Research Nuclear University ' ' MEPhI' ' , Kashirskoe Shosse 31, 115409, Moscow (Russian Federation)

2016-04-15

We report the study of transport and magnetic properties of the YbB{sub 6-δ}single crystals grown by inductive zone melting. A strong disparity in the low temperature resistivity, Seebeck and Hall coefficients is established for the samples with the different level of boron deficiency. The effective parameters of the charge transport in YbB{sub 6-δ} are shown to depend on the concentration of intrinsic defects, which is estimated to range from 0.09% to 0.6%. The pronounced variation of Hall mobility μ{sub H} found for bulk holes is induced by the decrease of transport relaxation time from τ ∼ 7.7 fs for YbB{sub 5.994} to τ ∼ 2.2 fs for YbB{sub 5.96}. An extra contribution to conductivity from electrons with μ{sub H}∼ -1000 cm{sup 2} V{sup -1} s{sup -1} and the very low concentration n /n{sub Yb}∼ 10{sup -6} discovered below 20 K for all the single crystals under investigation is suggested to arise from the surface electron states appeared in the inversion layer due to the band bending. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Sr{sub 2}MgMoO{sub 6−δ} thin films fabricated using pulsed-laser deposition with high concentrations of oxygen vacancies

Energy Technology Data Exchange (ETDEWEB)

Shigematsu, K. [Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Chikamatsu, A., E-mail: chikamatsu@chem.s.u-tokyo.ac.jp; Fukumura, T. [Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); JST-CREST, Bunkyo-ku, Tokyo 113-0033 (Japan); Toyoda, S. [Department of Materials Science and Engineering, Kyoto University, Yoshida-honmachi, Kyoto 606-8501 (Japan); Ikenaga, E. [JASRI/SPring-8, Mikazuki-cho, Hyogo 679-5198 (Japan); Hasegawa, T. [Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); JST-CREST, Bunkyo-ku, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki, Kanagawa 213-0012 (Japan)

2014-06-30

We fabricated epitaxial thin films of oxygen-vacant Sr{sub 2}MgMoO{sub 6−δ} using pulsed laser deposition. The films showed low resistivity of the order of 10{sup −2} Ω cm at 300 K. X-ray diffraction analyses revealed that Mg and Mo ions in the Sr{sub 2}MgMoO{sub 6−δ} films were considerably disordered, compared to those in bulk Sr{sub 2}MgMoO{sub 6−δ}. The proportion of oxygen vacancies estimated through hard x-ray photoemission measurements was as large as 0.37, and correlated well with the Mg/Mo ordering.

Dependence of Parameters of Laser-Produced Au Plasmas on the Incident Laser Energy of Sub-Nanosecond and Picosecond Laser Pulses

International Nuclear Information System (INIS)

Woryna, E.; Badziak, J.; Makowski, J.; Parys, P.; Vankov, A.B.; Wolowski, J.; Krasa, J.; Laska, L.; Rohlena, K.

2001-01-01

The parameters of Au plasma as functions of laser energy for ps pulses are presented and compared with the ones for sub-ns pulses at nearly the same densities of laser energy. The experiments were performed at the IPPLM with the use of CPA (chirped pulse amplification) Nd:glass laser system. Thick Au foil targets were irradiated by normally incident focused laser beams with maximum intensities of 8x10 16 and 2x10 14 W/cm 2 for ps and sub-ns laser pulses, respectively. The characteristics of ion streams were investigated with the use of ion diagnostics methods based on the time-of flight technique. In these experiments the laser energies were changed in the range from 90 to 700 mJ and the measurements were performed at a given focus position FP = 0 and along the target normal for both the laser pulses. The charge carried by the ions, the maximum ion velocities of fast and thermal ion groups, the maximum ion current density as well as the area of photopeak in dependence on the incident laser energy for sub-ns and ps pulses were investigated and discussed. (author)

UV-C irradiation of HSV-1 infected fibroblasts (HSV-FS) enhances human natural killer (NK) cell activity against these targets

International Nuclear Information System (INIS)

Pettera, L.; Fitzgerald-Bocarsly, P.

1991-01-01

Expression of Herpes Simplex Virus Type 1 (HSV-1) immediate early gene products has been bound to be sufficient for NK cell mediated lysis of HSV-1 infected FS. To block the targets at various stages in the infectious cycle, HSV-FS were irradiated with UV light for 1 min at 2, 6, and 20 hr post-infection. NK mediated lysis of 2 hr and 5 hr UV treated HSV-FS was 2-fold higher than non-UV treated HSV-FS despite a >99% inhibition in virus yield. In contrast, 20 hr infected targets were lysed less well than 2 and 6 hr targets despite strong glycoprotein expression and induction of high levels of interferon-alpha (IFN-α) production by effector PBMC's; this lysis was not enhanced by UV treatment. Since NK lysis of HSV-FS has been found to be dependent on an HLA-DR + accessory cell (AC), lysis of irradiated HSV-FS by PBMC's depleted of AC was measured. Such depletion eradicated NK lysis of the UV treated HSV-FS indicating that irradiation does not overcome the AC requirement for NK lysis. UV irradiation of another HLA-DR + dependent target, Vesicular Stomatitis Virus (VSV) infected FS led to a dramatic reduction in both NK lysis and IFN-α induction. HSV-1 is a DNA virus whose genes are expressed in a cascade fashion whereas VSV is an RNA virus. The authors hypothesize that the enhancement in AC dependent NK activity observed for UV irradiated HSV-FS, but not VSV-FS, targets is due to overproduction of either a cellular or viral gene product which specifically occurs early in the HSV-1 infectious cycle and is downregulated by 20 hr post-infection

Up-conversion luminescent properties of La{sub (0.80−x)}VO{sub 4}:Yb{sub x}, Er{sub 0.20} phosphors

Energy Technology Data Exchange (ETDEWEB)

Choi, Dong Hwa; Kang, Deok Hwa [Department of Materials Science and Engineering, Silla University, Busan 617-736 (Korea, Republic of); Yi, Soung Soo, E-mail: ssyi@silla.ac.kr [Department of Materials Science and Engineering, Silla University, Busan 617-736 (Korea, Republic of); Jang, Kiwan [Department of Physics, Changwon National University, Changwon 641-773 (Korea, Republic of); Jeong, Jung Hyun [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

2015-11-15

Highlights: • A novel green and red emitting LaVO{sub 4}:Yb{sub x}{sup 3+}, Er{sub 0.20}{sup 3+} phosphors were synthesized. • Their structures, luminescent properties have also been investigated. • Major laser transition for Er{sup 3+} ion is {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2} (525 nm). • These results suggest the possibility as photonic devices. - Abstract: Yb{sup 3+}, Er{sup 3+} co-doped LaVO{sub 4} phosphors were synthesized by solid state reaction method. Yb{sup 3+} concentrations were changed from 0.01 to 0.20 mol for the fixed Er{sup 3+} concentration at 0.2 mol. The crystalline structure of samples was investigated by X-ray diffraction (XRD). The composition was investigated by X-ray photoelectron spectroscopy (XPS) analysis. The surface morphology was observed by scanning electron microscope (SEM). The red and green up-conversion emissions were observed in Yb{sup 3+}, Er{sup 3+} co-doped LaVO{sub 4} phosphors under the excitation of 980 nm laser diode. Several emissions in green and red regions of the spectrum were observed near 525 nm, 553 nm and 659 nm radiated by {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}, {sup 4}S{sub 3/2} → {sup 4}I{sub 15/2}, and {sup 4}F{sub 3/2} → {sup 4}I{sub 15/2} transitions, respectively.

Magnesium doped gallium phosphonates Ga{sub 1-x}Mg{sub x}[H{sub 3+x}(O{sub 3}PCH{sub 2}){sub 3}N] (x = 0, 0.20) and the influence on proton conductivity

Energy Technology Data Exchange (ETDEWEB)

Homburg, Thomas; Reinsch, Helge; Stock, Norbert [Institut fuer Anorganische Chemie, Christian-Albrechts-Universitaet, Kiel (Germany); Tschense, Carsten B.L.; Senker, Juergen [Dept. of Inorganic Chemistry III, University of Bayreuth (Germany); Wolkersdoerfer, Konrad; Wark, Michael [Institut fuer Chemie, Carl von Ossietzky Universitaet Oldenburg (Germany); Toebbens, Daniel; Zander, Stefan [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany)

2018-02-01

In our contribution to the development of new proton conductive coordination polymers (CPs) we focus on the impact of a partial replacement of Ga{sup 3+} by Mg{sup 2+}. This approach should come along with the introduction of additional protons due to charge balances. In a first step we have synthesized an isostructural compound to the literature known compound AlH{sub 3}P3N [H{sub 6}P3N = nitrilotris(methylene)triphosphonic acid], where Al{sup 3+} is replaced by Ga{sup 3+}, since all attempts to incorporate Mg{sup 2+} ions directly into AlH{sub 3}P3N were not successful. The relative amount of Mg{sup 2+} and Ga{sup 3+} was established by EDX analysis. Rietveld refinement of the synchrotron data located the Ga{sup 3+} and Mg{sup 2+} ions on a split position, proving the disordered incorporation of the Mg{sup 2+} ions. Solid-state NMR spectroscopy confirms a disordered protonation of the phosphonate groups as well and shows that all amine groups are protonated. In order to investigate the effect on the proton conductivity the compounds Ga[H{sub 3}(O{sub 3}PCH{sub 2}){sub 3}N], denoted GaH{sub 3}P3N as well as Ga{sub 0.80}Mg{sub 0.20}[H{sub 3.20}(O{sub 3}PCH{sub 2}){sub 3}N], denoted GaMgH{sub 3.20}P3N, were characterized by electrochemical impedance spectroscopy (EIS). Arrhenius behavior in the investigated temperature range (70-130 C) was found for both compounds (activation energies of E{sub a} = 0.15 eV for GaH{sub 3}P3N and 0.17 eV for GaMgH{sub 3.20}P3N). The GaMgH{sub 3.20}P3N sample shows a reduced proton mobility (σ = 1.2 x 10{sup -4} S.cm{sup -1}) of about one order of magnitude in comparison to GaH{sub 3}P3N (σ = 1.0 x 10{sup -3} S.cm{sup -1}). (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Incubation and nanostructure formation on n- and p-type Si(1 0 0) and Si(1 1 1) at various doping levels induced by sub-nanojoule femto- and picosecond near-infrared laser pulses

International Nuclear Information System (INIS)

Schüle, M.; Afshar, M.; Feili, D.; Seidel, H.; König, K.; Straub, M.

2014-01-01

Highlights: • Nanorifts, ripples of period 130 nm and randomly nanoporous surface structures were generated. • Such nanostructures emerged on heavily and lightly n- and p-doped Si(1 0 0) and Si(1 1 1) surfaces. • Strong incubation occurred irrespective of dopant type and concentration or surface orientation. • Incubation is attributed to photoexcitation from laser-induced defect states in the bandgap. • Aggregation of defects results in nanocracks, which turn into nanorift and nanoripple patterns. • Ablation involved predominantly single-photon processes but also multiphoton absorption. - Abstract: N- and p-doped Si(1 0 0) and Si(1 1 1) surfaces with dopant concentrations of 2 × 10 14 –1 × 10 19 cm −3 were irradiated by tightly focused 85-MHz repetition rate Ti:sapphire laser light (central wavelength 800 nm, bandwidth 120 nm) at pulse durations of 12 fs to 1.6 ps. Dependent on pulse peak intensity and exposure time nanorifts, ripples of period 130 nm as well as sponge-like randomly nanoporous surface structures were generated with water immersion and, thereafter, laid bare by etching off aggregated oxide nanoparticles. The same structure types emerged in air or water with transform-limited 100-fs pulses. At a pulse length of 12 fs pronounced incubation occurred with incubation coefficients S = 0.66–0.85, whereas incubation was diminished for picosecond pulses (S > 0.95). The ablation threshold strongly rose with dopant concentration. At similar doping level it was higher for n-type than for p-type samples and for Si(1 0 0) compared to Si(1 1 1) surfaces. These observations are attributed to laser-induced defect states in the bandgap which participate in photoexcitation, deactivation of dopants by complex formation, and different densities of interface states at the boundary with the ultrathin native silicon dioxide surface layer. The threshold increase with pulse length revealed predominant single-photon excitation as well as multiphoton

Pulse compression system for the ANL 20 MeV linac

International Nuclear Information System (INIS)

Mavrogenes, G.; Norem, J.; Simpson, J.

1986-01-01

This paper describes the pulse compression system being built on the Argonne 20 MeV electron linac. The system is designed to rotate the bunch from the present measured pulse length of 38 psec FWHM, to pulse lengths of 5 to 6 ps with the large instantaneous currents (1 to 4 kA) possible instantaneous current. This system was necessary to extend the study of reactive fragments of molecules to the time scale of a few picoseconds, in particular to examine the chemistry of electrons and ions before and during relaxation of the surrounding media. These experiments are not sensitive to the beam energy spread, High Energy Physics experiments studying wake fields have also been proposed using the short bunches and the facility was designed so that the wake field experiment could share the beam bunching system. The 20 MeV electron linac uses a double gap, 12th subharmonic prebuncher together with a one wavelength 1.3 Ghz prebuncher to produce a single pulse of 38 ps from one occupied rf bucket. Beam emittances of 15.7 mmmr have been measured for 40 nC of accelerated charge and 8 mmmr at 10 nC. The energy spread of dE/E = 1% (FWHM) has been measured at 40 nC. Thus the accelerated beam has excellent time structure, high current, and good emittance

Measuring sub-bandage pressure: comparing the use of pressure monitors and pulse oximeters.

Science.gov (United States)

Satpathy, A; Hayes, S; Dodds, S R

2006-03-01

To test the use of low-cost sub-bandage pressure monitors and pulse oximeters as part of a quality-control measure for graduated compression bandaging in leg ulcer clinics. Twenty-five healthy volunteers (mean age 40 years) providing 50 limbs were bandaged with a four-layer compression bandaging system. The ankle systolic pressure (ASP) was measured using a pulse oximeter (Nellcor NBP-40) before applying the graduated compression bandages. Interface pressure was measured by placing pressure sensors on the skin at three points (2cm above the medial malleolus; the widest part of the calf; and a point midway between them) in the supine and standing positions. The ASP was measured again with the pulse oximeter after the bandage had been applied, and the effect of the bandage on the ASP was recorded. The actual pressure created by the bandage was compared with the required pressure profile. Interface pressures varied with change of position and movement. With the operator blinded to the pressure monitors while applying the bandages, the target pressure of 35-40mmHg at the ankle was achieved in only 36% of limbs ([mean +/- 95% confidence interval]; 32.3 +/- 1.6mmHg [supine]; 38.4 +/- 2.4mmHg [standing position]). With the help of the pressure monitors, the target pressure was achieved in 78% of the limbs. There was no correlation between the pressure monitors and pulse oximeter pressures, demonstrating that the pulse oximeter is not a useful tool for measuring sub-bandage pressures. The results suggest a tool (interface pressure monitors) that is easy to operate should be available as part of quality assurance for treatment, training of care providers and education.

Epitaxial Fe{sub 3-x}Ti{sub x}O{sub 4} films from magnetite to ulvöspinel by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Droubay, T.C.; Pearce, C.I.; Ilton, E.S.; Engelhard, M.H.; Engelhard, M.H.; Heald, S.M.; Arenholz, E.; Rosso, K.M.

2011-07-21

Epitaxial films along the Fe{sub 3-x}Ti{sub x}O{sub 4} (titanomagnetite) compositional series from pure end-members magnetite (Fe{sub 3}O{sub 4}) to ulvöspinel (Fe{sub 2}TiO{sub 4}) were successfully grown by pulsed laser deposition on MgO(100) substrates. Spectroscopic characterization including high resolution x-ray diffraction, x-ray photoelectron spectroscopy, and synchrotron-based x-ray absorption and magnetic circular dichroism consistently shows that Ti(IV) substitutes for Fe(III) in the inverse spinel lattice with a proportional increase in lattice Fe(II) concentration. No evidence of Ti interstitials, spinodal decomposition, or secondary phases was found in the bulk of the grown films. At the uppermost few nanometers of the Ti-bearing film surfaces, evidence suggests that Fe(II) is susceptible to facile oxidation, and that an associated lower Fe/Ti ratio in this region is consistent with surface compositional incompleteness or alteration to a titanomaghemite-like composition and structure. The surface of these films nonetheless appear to remain highly ordered and commensurate with the underlying structure despite facile oxidation, a surface condition that is found to be reversible to some extent by heating in low oxygen environments.

Surface treatment of diamond-like carbon films by reactive Ar/CF{sub 4} high-power pulsed magnetron sputtering plasmas

Energy Technology Data Exchange (ETDEWEB)

Kimura, Takashi, E-mail: t-kimura@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Nishimura, Ryotaro [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Azuma, Kingo [Department of Electrical Engineering and Computer Sciences, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Nakao, Setsuo; Sonoda, Tsutomu; Kusumori, Takeshi; Ozaki, Kimihiro [National Institute of Advanced Industrial Science and Technology (AIST) - Chubu, 2266-98 Anagahora, Moriyama, Nagoya 463-8560 (Japan)

2015-12-15

Surface modification of diamond-like carbon films deposited by a high-power pulsed magnetron sputtering (HPPMS) of Ar was carried out by a HPPMS of Ar/CF{sub 4} mixture, changing a CF{sub 4} fraction from 2.5% to 20%. The hardness of the modified films markedly decreased from about 13 to about 3.5 GPa with increasing CF{sub 4} fraction, whereas the water contact angle of the modified films increased from 68° to 109° owing to the increase in the CF{sub x} content on the film surface. C 1s spectra in X-ray photoelectron spectroscopy indicated that a graphitic structure of modified films was formed at CF{sub 4} fractions less than 5%, above which the modified films possessed a polymer-like structure. Influence of treatment time on the properties of the modified films was also investigated in the range of treatment time from 5 to 30 min. The properties of the modified films did not depend on the treatment time in the range of treatment time longer than 10 min, whereas the water contact angle was not sensitive to the treatment time at any treatment time.

Studies on laser material processing with nanosecond and sub-nanosecond and picosecond and sub-picosecond pulses

Science.gov (United States)

Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

2016-03-01

In this paper, laser ablation of widely used metal (Al, Cu. stainless-steel), semiconductor (Si), transparent material (glass, sapphire), ceramic (Al2O3, AlN) and polymer (PI, PMMA) in industry were systematically studied with pulse width from nanosecond (5-100ns), picosecond (6-10ps) to sub-picosecond (0.8-0.95ps). A critical damage zone (CDZ) of up to 100um with ns laser, efficiency were also investigated. This is to explore how to provide industry users the best laser solution for device micro-fabrication with best price. Our studies of cutting and drilling with ns, ps, and sub-ps lasers indicate that it is feasible to achieve user accepted quality and speed with cost-effective and reliable laser by optimizing processing conditions.

An ultrashort pulse ultra-violet radiation undulator source driven by a laser plasma wakefield accelerator

Energy Technology Data Exchange (ETDEWEB)

Anania, M. P. [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); INFN, Laboratori Nazionali di Frascati, I-00044 Frascati (Italy); Brunetti, E.; Wiggins, S. M.; Grant, D. W.; Welsh, G. H.; Issac, R. C.; Cipiccia, S.; Shanks, R. P.; Manahan, G. G.; Aniculaesei, C.; Jaroszynski, D. A., E-mail: d.a.jaroszynski@strath.ac.uk [SUPA, Department of Physics, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Geer, S. B. van der; Loos, M. J. de [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands); Poole, M. W.; Shepherd, B. J. A.; Clarke, J. A. [ASTeC, STFC, Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Gillespie, W. A. [SUPA, School of Engineering, Physics and Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom); MacLeod, A. M. [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee DD1 1HG (United Kingdom)

2014-06-30

Narrow band undulator radiation tuneable over the wavelength range of 150–260 nm has been produced by short electron bunches from a 2 mm long laser plasma wakefield accelerator based on a 20 TW femtosecond laser system. The number of photons measured is up to 9 × 10{sup 6} per shot for a 100 period undulator, with a mean peak brilliance of 1 × 10{sup 18} photons/s/mrad{sup 2}/mm{sup 2}/0.1% bandwidth. Simulations estimate that the driving electron bunch r.m.s. duration is as short as 3 fs when the electron beam has energy of 120–130 MeV with the radiation pulse duration in the range of 50–100 fs.

Few-cycle isolated attosecond pulses

International Nuclear Information System (INIS)

Sansone, G.; Benedetti, E.; Calegari, F.; Stagira, S.; Vozzi, C.; Silvestri De, S.; Nisoli, M.

2006-01-01

Complete test of publication follows. In the last few years the field of attosecond science has shown impressive and rapid progress, mainly due to the introduction of novel experimental methods for the characterization of extreme ultraviolet (XUV) pulses and attosecond electron wave packets. This development has been also triggered by significant improvements in the control of the electric field of the driving infrared pulses. Particularly interesting for the applications is the generation of isolated attosecond XUV pulses using few-cycle driving pulses. In this case significant progresses have been achieved thanks to the stabilization of the carrier-envelope phase (CEP) of amplified light pulses. In this work we demonstrate that the polarization gating (PG) method with few-cycle phase-stabilized driving pulses allows one to generate few-cycle isolated attosecond pulses tunable on a very broad spectral region. The PG method is based on temporal modulation of the ellipticity of a light pulse, which confines the XUV emission in the temporal gate where the polarization is close to linear. The time-dependent polarization of phase-stabilized sub-6-fs pulses, generated by the hollow fiber technique, has been obtained using two birefringent plates. It is possible to create a linear polarization gate, whose position is imposed by the intensity profile of the pulse whilst the emission time is linked to the CEP of the electric field. The pulses have been analyzed by using a flat-field spectrometer. Continuous XUV spectra, corresponding to the production of isolated attosecond pulses, have been generated for particular CEP values. Upon changing the rotation of the first plate it was possible to tune the XUV emission in a broad spectra range. We have then achieved a complete temporal characterization of the generated isolated attosecond pulses using frequency-resolved optical gating for complete reconstruction of attosecond bursts (FROG CRAB). The measured parabolic phase

Sub-50-as isolated extreme ultraviolet continua generated by 1.6-cycle near-infrared pulse combined with double optical gating scheme

Science.gov (United States)

Oguri, Katsuya; Mashiko, Hiroki; Ogawa, Tatsuya; Hanada, Yasutaka; Nakano, Hidetoshi; Gotoh, Hideki

2018-04-01

We demonstrate the generation of ultrabroad bandwidth attosecond continua extending to sub-50-as duration in the extreme ultraviolet (EUV) region based on a 1.6-cycle Ti:sapphire laser pulse. The combination of the amplitude gating scheme with a sub-two-cycle driver pulse and the double optical gating scheme achieves the continuum generation with a bandwidth of 70 eV at the full width at half maximum near the peak photon energy of 140 eV, which supports a Fourier-transform-limited pulse duration as short as 32 as. The carrier-envelope-phase (CEP) dependence of the attosecond continua shows a single-peak structure originating from the half-cycle cut-off at appropriate CEP values, which strongly indicates the generation of a single burst of an isolated attosecond pulse. Our approach suggests a possibility for isolated sub-50-as pulse generation in the EUV region by compensating for the intrinsic attosecond chirp with a Zr filter.

Dynamics of Al/Fe{sub 2}O{sub 3} MIC combustion from short single-pulse photothermal initiation and time-resolved spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Stiegman, Albert E.; Park, Chi-Dong; Mileham, Melissa; Van de Burgt, Lambertus J. [Department of Chemistry and Biochemistry, Florida State University Tallahassee, FL (United States); Kramer, Michael P. [AFRL/MNME Eglin AFB, FL (United States)

2009-08-15

Time-resolved spectroscopy was used to study the dynamics of the photothermal ignition of Al/Fe{sub 2}O{sub 3} metastable intermolecular composites after single short-pulse laser initiation. The dynamics were recorded in several time domains from nanosecond to microsecond to quantify the dynamics from initial laser excitation to combustion. Time-averaged spectral data were also collected for the overall emission occurring during combustion. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Lane fuzzy collision in channel with potential deformation by photon-phonon-electron excitation and sub-atomic control

International Nuclear Information System (INIS)

Shen Jing

1998-01-01

Collision between μ + and the μ - beams in the crystal are forbidden due to the two beams having different ''lanes'' in a channel. A laser pulse of ps-fs shocks lattice kernel vibration and dilates lattice electron distribution. It deforms the Lindhard's potential which is then expressed in a quantized form as the Huang-Zhu's potential[1]. The dynamic lanes can be made to overlap in a channel to allow collision without ductile fracture. This raises a new technology of sub-atomic information and control, which has been raised by T. D. Lee

Acousto-optic replication of ultrashort laser pulses

Science.gov (United States)

Yushkov, Konstantin B.; Molchanov, Vladimir Ya.; Ovchinnikov, Andrey V.; Chefonov, Oleg V.

2017-10-01

Precisely controlled sequences of ultrashort laser pulses are required in various scientific and engineering applications. We developed a phase-only acousto-optic pulse shaping method for replication of ultrashort laser pulses in a TW laser system. A sequence of several Fourier-transform-limited pulses is generated from a single femtosecond laser pulse by means of applying a piecewise linear phase modulation over the whole emission spectrum. Analysis demonstrates that the main factor which limits maximum delay between the pulse replicas is spectral resolution of the acousto-optic dispersive delay line used for pulse shaping. In experiments with a Cr:forsterite laser system, we obtained delays from 0.3 to 3.5 ps between two replicas of 190 fs transform-limited pulses at the central wavelength of laser emission, 1230 nm.

Generalization of the Rabi population inversion dynamics in the sub-one-cycle pulse limit

International Nuclear Information System (INIS)

Doslic, N.

2006-01-01

We consider the population inversion in a two-level system generated by a sub-one-cycle pulse excitation. Specifically, we explore the effect that the time derivative of the pulse envelope has on the Rabi dynamics. Our analysis is based on a combination of analytical, perturbative, and nonperturbative treatments and is complemented by numerical simulations. We find a shortening of the Rabi inversion period and show that complete inversion is unobtainable under resonant, ultrashort pulse conditions. The impact of nonresonant and carrier-envelope phase-dependent effects on the dynamics of two-level and multilevel systems is studied numerically, and conditions for complete population inversion are derived

Numerical evidence for quadrupolar-octopolar order in RETM{sub 2}(Al,Zi){sub 20}

Energy Technology Data Exchange (ETDEWEB)

Attig, Jan [Institute for Theoretical Physics, University of Cologne (Germany); Tse, Darrell; Lee, Eric Kin-Ho; Paramekanti, Arun; Kim, Yong Baek [Department of Physics, University of Toronto, ON (Canada)

2016-07-01

Motivated by recent experiments on materials of the type RETM{sub 2}(Al,Zi){sub 20} (where RE is a rare earth and TM a transition metal element) we investigate a minimal model for the pseudo-spin degrees of freedom of the rare earth ions. The model is described by J1-J2 pseudo-spin interactions in three-dimensions where the XY part models quadrupolar order and the Ising part models octopolar order. We use various computational methods such as simulating annealing to find the zero temperature phase digram and investigate further by using single-spin flip Monte Carlo simulations for finite temperature. One notable finding is the existence of non-coplanar spiral ordering of pseudo-spins, which may explain some of the experimental data on the electronic ordering in RETM{sub 2}(Al,Zi){sub 20}.

FS65 Disposition Option Report

Energy Technology Data Exchange (ETDEWEB)

Wenz, Tracy R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-09-25

This report outlines the options for dispositioning the MOX fuel stored in FS65 containers at LANL. Additional discussion regarding the support equipment for loading and unloading the FS65 transport containers is included at the end of the report.

Diode-pumped passively mode-locked sub-picosecond Yb:LuAG ceramic laser

International Nuclear Information System (INIS)

Zhu Jiang-Feng; Liu Kai; Wang Jun-Li; Yang Yu; Wang Hui-Bo; Gao Zi-Ye; Jiang Li; Xie Teng-Fei; Chao-Yu Li; Pan Yu-Bai; Wei Zhi-Yi

2017-01-01

In this paper the laser activities of a diode-pumped Yb:LuAG ceramic which was prepared by the solid-state reactive sintering method were reported. The maximum output power was 1.86 W in the continuous wave (CW) laser operation, corresponding to a slope efficiency of 53.6%. The CW laser could be tuned from 1030 to 1096 nm by inserting a prism in the cavity. With the assist of a semiconductor saturable absorber mirror (SESAM), passive mode-locking was realized, delivering sub-picosecond pulses with 933 fs duration and an average power of 532 mW at a repetition rate of 90.35 MHz. (paper)

Pulsed laser deposited MnCo{sub 2}O{sub 4} protective layer on SS430 for solid oxide fuel cell application

Energy Technology Data Exchange (ETDEWEB)

Gaur, Anshu, E-mail: gauranshu20@gmail.com, E-mail: ahamed.vza@gmail.com; Mohiddon, Md. Ahamad, E-mail: gauranshu20@gmail.com, E-mail: ahamed.vza@gmail.com [National Institute of Technology Andhra Pradesh, Tadepalliguem 534101 (India); Prasad, Muvva D. [UGC Networking Centre, School of Chemistry, University of Hyderabad, Hyderabad 500046, India. Phone:+91-40-23134382, Fax:+91-40-23010227 (India)

2016-05-23

The growth and oxidation study of pulsed laser deposited MnCo{sub 2}O{sub 4} protective layer on SS430 substrate for solid oxide fuel cell application is demonstrated. MnCo{sub 2}O{sub 4} has been achieved in three different ways including, deposition at higher substrate temperature (700°C), and deposition at room temperature on pre-oxidized and untreated SS430 substrate followed by annealing at 700°C for 2 hrs. X-ray diffraction and Raman spectroscopy has been applied to demonstrate the kind of phases developed in each case. These three samples were subjected to heat treatment at 750°C for 5 hr. The extent of undesired Fe{sub 2}O{sub 3} phase formation in the post deposition heat treated samples is discussed based on Raman spectroscopic results.

Proton-induced nanorod melting in a coating obtained from the pulsed laser ablation of W{sub 2}B{sub 5}/B{sub 4}C

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville Campus, PO Box 1906, Bellville 7530 (South Africa); Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques, Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar-Fann, Dakar (Senegal); Cummings, F. [Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Kotsedi, L. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050, Johannesburg (South Africa); Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); and others

2015-02-01

Highlights: • Coatings from ablated B{sub 4}C/W{sub 2}B{sub 5} were irradiated with 900 keV protons. • Nanorod clusters were observed to melt and disperse. • Uniformly shaped nanorods were observed to grow. • Lateral diffusion of energy and lateral dispersion of matter were observed. - Abstract: Coatings obtained from pulsed laser ablated W{sub 2}B{sub 5}/B{sub 4}C were irradiated with 900keV protons at fluences ranging from about 1×10{sup 15}protons/cm{sup 2} to about 4×10{sup 15}protons/cm{sup 2}. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to study the resulting structural effects. Clusters of nanorods were observed to disperse and reduce in number with increase in proton fluence. The atomic percentage of constituent elements were observed to vary with proton fluence, both within the nanorods and the film floor. Our results show that the structural effect of proton irradiation on the coating is lateral dispersion of matter.

Note: Large active area solid state photon counter with 20 ps timing resolution and 60 fs detection delay stability

Science.gov (United States)

Prochazka, Ivan; Kodet, Jan; Eckl, Johann; Blazej, Josef

2017-10-01

We are reporting on the design, construction, and performance of a photon counting detector system, which is based on single photon avalanche diode detector technology. This photon counting device has been optimized for very high timing resolution and stability of its detection delay. The foreseen application of this detector is laser ranging of space objects, laser time transfer ground to space and fundamental metrology. The single photon avalanche diode structure, manufactured on silicon using K14 technology, is used as a sensor. The active area of the sensor is circular with 200 μm diameter. Its photon detection probability exceeds 40% in the wavelength range spanning from 500 to 800 nm. The sensor is operated in active quenching and gating mode. A new control circuit was optimized to maintain high timing resolution and detection delay stability. In connection to this circuit, timing resolution of the detector is reaching 20 ps FWHM. In addition, the temperature change of the detection delay is as low as 70 fs/K. As a result, the detection delay stability of the device is exceptional: expressed in the form of time deviation, detection delay stability of better than 60 fs has been achieved. Considering the large active area aperture of the detector, this is, to our knowledge, the best timing performance reported for a solid state photon counting detector so far.

High-Average-Power Diffraction Pulse-Compression Gratings Enabling Next-Generation Ultrafast Laser Systems

Energy Technology Data Exchange (ETDEWEB)

Alessi, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-11-01

Pulse compressors for ultrafast lasers have been identified as a technology gap in the push towards high peak power systems with high average powers for industrial and scientific applications. Gratings for ultrashort (sub-150fs) pulse compressors are metallic and can absorb a significant percentage of laser energy resulting in up to 40% loss as well as thermal issues which degrade on-target performance. We have developed a next generation gold grating technology which we have scaled to the petawatt-size. This resulted in improvements in efficiency, uniformity and processing as compared to previous substrate etched gratings for high average power. This new design has a deposited dielectric material for the grating ridge rather than etching directly into the glass substrate. It has been observed that average powers as low as 1W in a compressor can cause distortions in the on-target beam. We have developed and tested a method of actively cooling diffraction gratings which, in the case of gold gratings, can support a petawatt peak power laser with up to 600W average power. We demonstrated thermo-mechanical modeling of a grating in its use environment and benchmarked with experimental measurement. Multilayer dielectric (MLD) gratings are not yet used for these high peak power, ultrashort pulse durations due to their design challenges. We have designed and fabricated broad bandwidth, low dispersion MLD gratings suitable for delivering 30 fs pulses at high average power. This new grating design requires the use of a novel Out Of Plane (OOP) compressor, which we have modeled, designed, built and tested. This prototype compressor yielded a transmission of 90% for a pulse with 45 nm bandwidth, and free of spatial and angular chirp. In order to evaluate gratings and compressors built in this project we have commissioned a joule-class ultrafast Ti:Sapphire laser system. Combining the grating cooling and MLD technologies developed here could enable petawatt laser systems to

Bright broadband coherent fiber sources emitting strongly blue-shifted resonant dispersive wave pulses

DEFF Research Database (Denmark)

Tu, Haohua; Lægsgaard, Jesper; Zhang, Rui

2013-01-01

We predict and realize the targeted wavelength conversion from the 1550-nm band of a fs Er:fiber laser to an isolated band inside 370-850 nm, corresponding to a blue-shift of 700-1180 nm. The conversion utilizes resonant dispersive wave generation in widely available optical fibers with good...... efficiency (~7%). The converted band has a large pulse energy (~1 nJ), high spectral brightness (~1 mW/nm), and broad Gaussian-like spectrum compressible to clean transform-limited ~17 fs pulses. The corresponding coherent fiber sources open up portable applications of optical parametric oscillators and dual......-output synchronized ultrafast lasers....

Optic fiber pulse-diagnosis sensor of traditional Chinese medicine

Science.gov (United States)

Ni, J. S.; Jin, W.; Zhao, B. N.; Zhang, X. L.; Wang, C.; Li, S. J.; Zhang, F. X.; Peng, G. D.

2013-09-01

The wrist-pulse is a kind of signals, from which a lot of physiological and pathological status of patients are deduced according to traditional Chinese medicine theories. This paper designs a new optic fiber wrist-pulse sensor that based on a group of FBGs. Sensitivity of the optic fiber wrist-pulse measurement system reaches 0.05% FS and the range reaches 50kPa. Frequency response is from 0 Hz to 5 kHz. A group of typical pulse signal is given out in the paper to compare different status of patient. It will improve quantification of pulse diagnosis greatly.

Pulsed transport critical currents of Bi2212 tapes in pulsed magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Rogacki, K [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland); Gilewski, A; Klamut, J [International Laboratory of High Magnetic Fields and Low Temperatures, Polish Academy of Sciences, Wroclaw (Poland); Newson, M; Jones, H [Clarendon Laboratory, University of Oxford, Oxford (United Kingdom); Glowacki, B A [IRC in Superconductivity and Department of Materials Science, University of Cambridge, Cambridge (United Kingdom)

2002-07-01

If high-T{sub C} superconductors are ever to be used in high-field applications, it is vital that the critical surfaces can be mapped under high-field conditions. However, the latest superconductors have high currents even at fields over 20 T, making accurate measurements very difficult due to the thermal and mechanical problems. In this paper, we compare measurements on BSCCO-2212 tape using a number of different methods, particularly an innovative pulsed transport current and pulsed field mode. We show how the analysis of the voltage signal from BSCCO-2212 tape in pulsed conditions may be used to extract the critical current in quasi-stationary conditions. The effect of a metallic substrate on the results is also briefly discussed. (author)

Quasicrystalline phase formation in the mechanically alloyed Al{sub 70}Cu{sub 20}Fe{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Medeiros, S. N. de, E-mail: snm@dfi.uem.br; Cadore, S.; Pereira, H. A.; Santos, I. A.; Colucci, C. C.; Paesano, A. [Universidade Estadual de Maringa, Departamento de Fisica (Brazil)

2010-01-15

In the present work, the formation of the Al{sub 70}Cu{sub 20}Fe{sub 10} icosahedral phase by mechanical alloying the elemental powders in a high-energy planetary mill was investigated by X-ray diffraction and Moessbauer spectroscopy. It was verified that the sample milled for 80 h produces an icosahedral phase besides Al(Cu, Fe) solid solution ({beta}-phase) and Al{sub 2}Cu intermetallic phase. The Moessbauer spectrum for this sample was fitted with a distribution of quadrupole splitting, a doublet and a sextet, revealing the presence of the icosahedral phase, {beta}-phase and {alpha}-Fe, respectively. This compound is not a good hydrogen storage. The results of the X-ray diffraction and Moessbauer spectroscopy of the sample milled for 40 h and annealed at 623 deg. C for 16 h shows essentially single i-phase and tetragonal Al{sub 7}Cu{sub 2} Fe phase.

Deposition and characterization of pulsed direct current magnetron sputtered Al{sub 95.5}Cr{sub 2.5}Si{sub 2} (N{sub 1-x}O{sub x}) thin films

Energy Technology Data Exchange (ETDEWEB)

Najafi, H., E-mail: hossein.najafi@epfl.c [Institut de Physique de la Matiere Condensee (IPMC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Lausanne (Switzerland); Shetty, A.; Karimi, A. [Institut de Physique de la Matiere Condensee (IPMC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Lausanne (Switzerland); Morstein, M. [Platit AG, Advanced Coating Systems, CH-2545 Selzach (Switzerland)

2010-10-29

Aluminum rich oxynitride thin films were prepared using pulsed direct current (DC) magnetron sputtering from an Al{sub 95.5}Cr{sub 2.5}Si{sub 2} (at.%) target. Two series of films were deposited at 400 {sup o}C and 650 {sup o}C by changing the O{sub 2}/(O{sub 2} + N{sub 2}) ratio in the reactive gas from 0% (pure nitrides) to 100% (pure oxides). The films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and nanoindentation. The results showed the existence of three different regions of microstructure and properties with respect to the oxygen concentration. For the samples deposited at 650 {sup o}C in the nitrogen rich region (O{sub 2}/(O{sub 2} + N{sub 2}) {<=} 0.08), the formation of the h-AlN (002) and Al-N bond were confirmed by XRD and XPS measurements. The hardness of the films was around 30 GPa. In the intermediate region (0.08 {<=} O{sub 2}/(O{sub 2} + N{sub 2}) {<=} 0.24), the presence of an amorphous structure and the shifting of the binding energies to lower values corresponding to non-stoichiometric compounds were observed and the hardness decreased to 12 GPa. The lowering of mechanical properties was attributed to the transition of the clean target to the reacted target under non-steady state deposition conditions. In the oxygen rich region (0.24 {<=} (O{sub 2}/(O{sub 2} + N{sub 2}) {<=} 1), the existence of {alpha}-Al{sub 2}O{sub 3}-(113), {alpha}-Al{sub 2}O{sub 3}-(116) and Al-O bonds confirmed the domination of this phase in this region of deposition and the hardness increased again to 30-35 GPa. Films deposited at 400 {sup o}C showed the same behavior except in the oxygen rich region, where hardness remains low at about 12-14 GPa.

EST Table: FS904516 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available 1461 10/09/10 48 %/243 aa gnl|Amel|GB18846-PA 10/09/10 46 %/242 aa gi|91086187|ref|XP_971225.1| PREDICTED: similar to medulloblastoma...oblastoma antigen MU-MB-50.4 [Tribolium castaneum] gb|EFA06682.1| hypothetical prot...FS904516 E_FL_fufe_02D20_F_0 11/12/09 n.h 10/09/28 46 %/242 aa ref|XP_971225.1| PREDICTED: similar to medull

Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

Energy Technology Data Exchange (ETDEWEB)

Bin Mansoor, Saad; Sami Yilbas, Bekir, E-mail: bsyilbas@kfupm.edu.sa

2015-08-15

Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system.

Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

International Nuclear Information System (INIS)

Bin Mansoor, Saad; Sami Yilbas, Bekir

2015-01-01

Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system

Ferromagnetic resonance studies on (Co{sub 40}Fe{sub 40}B{sub 20}){sub x}(SiO{sub 2}){sub 1-x} granular magnetic films

Energy Technology Data Exchange (ETDEWEB)

Yildiz, F. [Department of Physics, Faculty of Sciences and Arts, Celal Bayar University, Muradiye/Manisa (Turkey) and Department of Physics, Electron Spin Science Center, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)]. E-mail: fyildiz@gyte.edu.tr; Kazan, S. [Gebze Institute of Technology, 41400 Gebze-Kocaeli (Turkey); Aktas, B. [Gebze Institute of Technology, 41400 Gebze-Kocaeli (Turkey); Tarapov, S.I. [Institute of Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkov 61085 (Ukraine); Tagirov, L. [Gebze Institute of Technology, 41400 Gebze-Kocaeli (Turkey); Granovsky, B. [Moscow State University, 119992 Moscow (Russian Federation)

2006-10-15

Magnetic properties of granular (Co{sub 40}Fe{sub 40}B{sub 20}){sub x}(SiO{sub 2}){sub 1-x} thin films (x=0.37-0.53) have been studied by ferromagnetic resonance (FMR) technique. Samples have been prepared by ion-beam deposition of Co-Fe-B particles and SiO{sub 2} on sitall ceramic substrate. The FMR measurements have been done for different orientations of DC magnetic field with respect to the sample plane. It was found that the deduced value of effective magnetization from FMR data of the thin granular film is reduced by the volume-filling factor of the bulk saturation magnetization. The overall magnetization changes from 152 to 515G depending on the ratio of the magnetic nanoparticles in the SiO{sub 2} matrix. From angular measurements an induced in-plane uniaxial anisotropy has been obtained due to the preparation of the film conditions as well.

Time- and angle-resolved photoemission spectroscopy with optimized high-harmonic pulses using frequency-doubled Ti:Sapphire lasers

International Nuclear Information System (INIS)

Eich, S.; Stange, A.; Carr, A.V.; Urbancic, J.; Popmintchev, T.; Wiesenmayer, M.; Jansen, K.; Ruffing, A.; Jakobs, S.; Rohwer, T.; Hellmann, S.; Chen, C.; Matyba, P.; Kipp, L.; Rossnagel, K.; Bauer, M.; Murnane, M.M.; Kapteyn, H.C.; Mathias, S.; Aeschlimann, M.

2014-01-01

Highlights: • We present a scheme to generate high intensity XUV pulses from HHG with variable time-bandwidth product. • Shorter-wavelength driven high-harmonic XUV trARPES provides higher photon flux and increased energy resolution. • High-quality high-harmonic XUV trARPES data with sub 150 meV energy and sub 30 fs time resolution is presented. - Abstract: Time- and angle-resolved photoemission spectroscopy (trARPES) using femtosecond extreme ultraviolet high harmonics has recently emerged as a powerful tool for investigating ultrafast quasiparticle dynamics in correlated-electron materials. However, the full potential of this approach has not yet been achieved because, to date, high harmonics generated by 800 nm wavelength Ti:Sapphire lasers required a trade-off between photon flux, energy and time resolution. Photoemission spectroscopy requires a quasi-monochromatic output, but dispersive optical elements that select a single harmonic can significantly reduce the photon flux and time resolution. Here we show that 400 nm driven high harmonic extreme-ultraviolet trARPES is superior to using 800 nm laser drivers since it eliminates the need for any spectral selection, thereby increasing photon flux and energy resolution to <150 meV while preserving excellent time resolution of about 30 fs

Note: Pulsed single longitudinal mode optical parametric oscillator for sub-Doppler spectroscopy of jet cooled transient species

Science.gov (United States)

Zhang, Qiang; Zhu, Boxing; Zhang, Deping; Gu, Jingwang; Zhao, Dongfeng; Chen, Yang

2017-12-01

We present a pulsed single longitudinal mode optical parametric oscillator that was recently constructed for sub-Doppler spectroscopic studies of transient species in a supersonic slit jet expansion environment. The system consists of a Littman-type grazing-incidence-grating resonator and a KTP crystal and is pumped at 532 nm. By spatially filtering the pump laser beam and employing an active cavity-length-stabilization scheme, a frequency down-conversion efficiency up to 18% and generation of Fourier-transform limited pulses with a typical pulse duration of ˜5.5 ns and a bandwidth less than 120 MHz have been achieved. In combination with a slit jet expansion, a sub-Doppler spectrum of SiC2 has been recorded at ˜498 nm, showing a spectral resolution of Δν/ν ≈ 6.2 × 10-7.

Nielsen: Aladdin-Suite, FS89. Maskarade-Overture / Robert Layton

Index Scriptorium Estoniae

Layton, Robert

1996-01-01

Uuest heliplaadist "Nielsen: Aladdin-Suite, FS89. Maskarade-Overture, Prelude, Act 2. The Cockerels' Dance. Rhapsody Overture: An imaginary journey to the Faroe Islands, FS123. Helios Overture, FS32. Saga-Drom, FS46. Pan and Syrinx, FS87. Gothenburg Symphony Orchestra, Neeme Järvi" DG 447 757-2GH (72 minutes: DDD)

Structural relaxations in the bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}

Energy Technology Data Exchange (ETDEWEB)

Błoch, K., E-mail: 23kasia1@wp.pl; Nabiałek, M.; Gondro, J.

2017-05-01

The paper presents studies of annealing effect on the disaccommodation phenomenon in bulk amorphous alloy Fe{sub 61}Co{sub 10}Ti{sub 3}Y{sub 6}B{sub 20}. The investigated sample was prepared by suction-casting method in the form of rod. The annealing process has been performed at temperature well below the crystallisation temperature. The amorphous structure has been confirmed using X-ray diffractometer. The susceptibility and its disaccommodation were determined using completely automated set up. The disaccommodation curve was decomposed into three elementary processes, each of them was described by Gaussian distribution of relaxation times. The obtained results indicate that the disaccommodation phenomenon in studied alloy is related with directional ordering of atom pairs near the free volumes; this is in agreement with H. Kronmüller's theorem.

Parametric study on femtosecond laser pulse ablation of Au films

International Nuclear Information System (INIS)

Ni Xiaochang; Wang Chingyue; Yang Li; Li Jianping; Chai Lu; Jia Wei; Zhang Ruobing; Zhang Zhigang

2006-01-01

Ablation process of 1 kHz rate femtosecond lasers (pulse duration 148 fs, wavelength 775 nm) with Au films on silica substrates has been systemically studied. The single-pulse threshold can be obtained directly. For the multiple pulses the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect. From the plot of accumulated laser fluence N x φ th (N) and the number of laser pulses N, incubation coefficient of Au film can be obtained (s = 0.765). As the pulse energy is increased, the single pulse ablation rate is increasing following two ablation logarithmic regimes, which can be explained by previous research

A phase stabilized and pulse shaped Ti:Sapphire oscillator-amplifier laser system for the LCLS rf photoinjector

International Nuclear Information System (INIS)

Kotseroglou, T.; Alley, R.; Clendenin, J.; Fisher, A.; Frisch, J.

1998-04-01

The authors have designed a laser system for the Linac Coherent Light Source rf photoinjector consisting of a Ti:Sapphire oscillator and 2 amplifiers using Chirped Pulse Amplification. The output after tripling will be 0.5 mJ tunable UV pulses at 120 Hz, with wavelength around 260 nm, pulsewidth of 10 ps FWHM and 200 fs rise and fall times. Amplitude stability is expected to be 1% rms in the UV and timing jitter better than 500 fs rms

Effect of boron incorporation on the structure and electrical properties of diamond-like carbon films deposited by femtosecond and nanosecond pulsed laser ablation

Energy Technology Data Exchange (ETDEWEB)

Sikora, A. [Laboratoire Hubert Curien, UMR 5516 CNRS, Universite Jean Monnet, 18 Rue Pr. Benoit Lauras, 42000 Saint-Etienne (France); Bourgeois, O. [Institut Neel, UPR 2940 CNRS, 25 Avenue des Martyrs, 38042 Grenoble Cedex 9 (France); Sanchez-Lopez, J.C. [Instituto de Ciencia de Materiales de Sevilla, Avda. Americo Vespucio, 49 41092 Sevilla (Spain); Rouzaud, J.-N. [Laboratoire de Geologie, UMR 8538 CNRS, Ecole Normale Superieure, 45 Rue d' Ulm, 75230 Paris Cedex 05 (France); Rojas, T.C. [Instituto de Ciencia de Materiales de Sevilla, Avda. Americo Vespucio, 49 41092 Sevilla (Spain); Loir, A.-S. [Laboratoire Hubert Curien, UMR 5516 CNRS, Universite Jean Monnet, 18 Rue Pr. Benoit Lauras, 42000 Saint-Etienne (France); Garden, J.-L. [Institut Neel, UPR 2940 CNRS, 25 Avenue des Martyrs, 38042 Grenoble Cedex 9 (France); Garrelie, F. [Laboratoire Hubert Curien, UMR 5516 CNRS, Universite Jean Monnet, 18 Rue Pr. Benoit Lauras, 42000 Saint-Etienne (France); Donnet, C., E-mail: christophe.donnet@univ-st-etienne.f [Laboratoire Hubert Curien, UMR 5516 CNRS, Universite Jean Monnet, 18 Rue Pr. Benoit Lauras, 42000 Saint-Etienne (France)

2009-12-31

The influence of the incorporation of boron in diamond-like carbon (DLC) films on the microstructure of the coatings has been investigated. The boron-containing DLC films (a-C:B) have been deposited by pulsed laser deposition (PLD) at room temperature in high vacuum conditions, by ablating graphite and boron targets either with a femtosecond pulsed laser (800 nm, 150 fs, fs-DLC) or with a nanosecond pulsed laser (248 nm, 20 ns, ns-DLC). Alternative ablation of the graphite and boron targets has been carried out to deposit the a-C:B films. The film structure and composition have been highlighted by coupling Field Emission Scanning Electron Microscopy, Electron Energy Loss Spectroscopy and High Resolution Transmission Electron Microscopy. Using the B K-edge, EELS characterization reveals the boron effect on the carbon bonding. Moreover, the plasmon energy reveals a tendency of graphitization associated to the boron doping. Pure boron particles have been characterized by HRTEM and reveal that those particles are amorphous or crystallized. The nanostructures of the boron-doped ns-DLC and the boron-doped fs-DLC are thus compared. In particular, the incorporation of boron in the DLC matrix is highlighted, depending on the laser used for deposition. Electrical measurements show that some of these films have potentialities to be used in low temperature thermometry, considering their conductivity and temperature coefficient of resistance (TCR) estimated within the temperature range 160-300 K.

Effects of moderate pump and Stokes chirp on chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering thermometry

KAUST Repository

Gu, Mingming; Satija, Aman; Lucht, Robert P.

2018-01-01

The effects of moderate levels of chirp in the pump and Stokes pulses on chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) were investigated. The frequency chirp in the pump and Stokes pulses was introduced

Type-I cascaded quadratic soliton compression in lithium niobate: Compressing femtosecond pulses from high-power fiber lasers

DEFF Research Database (Denmark)

Bache, Morten; Wise, Frank W.

2010-01-01

The output pulses of a commercial high-power femtosecond fiber laser or amplifier are typically around 300–500 fs with wavelengths of approximately 1030 nm and tens of microjoules of pulse energy. Here, we present a numerical study of cascaded quadratic soliton compression of such pulses in LiNbO3....... However, the strong group-velocity dispersion implies that the pulses can achieve moderate compression to durations of less than 130 fs in available crystal lengths. Most of the pulse energy is conserved because the compression is moderate. The effects of diffraction and spatial walk-off are addressed......, and in particular the latter could become an issue when compressing such long crystals (around 10 cm long). We finally show that the second harmonic contains a short pulse locked to the pump and a long multi-picosecond red-shifted detrimental component. The latter is caused by the nonlocal effects...

Optical and electrical properties of SnO2 thin films after ultra-short pulsed laser annealing

NARCIS (Netherlands)

Scorticati, D.; Illiberi, A.; Römer, G.R.B.E.; Bor, T.; Ogieglo, W.; Klein Gunnewiek, M.; Lenferink, A.; Otto, C.; Skolski, J.Z.P.; Grob, F.; Lange, D.F. de; Huis in 't Veld, A.J.

2013-01-01

Ultra-short pulsed laser sources, with pulse durations in the ps and fs regime, are commonly exploited for cold ablation. However, operating ultra-short pulsed laser sources at fluence levels well below the ablation threshold allows for fast and selective thermal processing. The latter is especially

Cross-validation of theoretically quantified fiber continuum generation and absolute pulse measurement by MIIPS for a broadband coherently controlled optical source

DEFF Research Database (Denmark)

Tu, H.; Liu, Y.; Lægsgaard, Jesper

2012-01-01

source with the MIIPS-integrated pulse shaper produces compressed transform-limited 9.6 fs (FWHM) pulses or arbitrarily shaped pulses at a central wavelength of 1020 nm, an average power over 100 mW, and a repetition rate of 76 MHz. In comparison to the 229-fs pump laser pulses that generate the fiber......The predicted spectral phase of a fiber continuum pulsed source rigorously quantified by the scalar generalized nonlinear Schrödinger equation is found to be in excellent agreement with that measured by multiphoton intrapulse interference phase scan (MIIPS) with background subtraction. This cross......-validation confirms the absolute pulse measurement by MIIPS and the transform-limited compression of the fiber continuum pulses by the pulse shaper performing the MIIPS measurement, and permits the subsequent coherent control on the fiber continuum pulses by this pulse shaper. The combination of the fiber continuum...

Beta decomposition of (Hf/sub x/Zr/sub 1-x/)80Nb20 ternary alloys

International Nuclear Information System (INIS)

Jones, W.B.; Taggart, R.; Polonis, D.H.

1978-01-01

The processes of beta decomposition have been examined in ternary alloys of the form (Hf/sub x/Zr/sub 1-x/) 80 Nb 20 to determine the influence of Hf additions to a basic Zr 80 Nb 20 composition. In the chill cast condition, Hf additions have been found to decrease the temperature coefficient of electrical resistivity from a value of -0.0015%/K for the binary Zr 80 Nb 20 alloy to a value of -0.011%/K for a (Hf 50 Zr 50 ) 80 Nb 20 ternary alloy. This change is explained in terms of the bcc lattice instability typical of Ti, Zr, and Hf alloys. The Hf additions enhance the kinetics of omega-phase precipitation during aging at 648 K. The aging of a (Hf 05 Zr 95 ) 80 Nb 20 alloy for 12 h results in the precipitation of a high volume fraction of cuboidal shaped omega-phase particles. A phase separation which results in the formation of solute lean discs (β/sub l/) occurs together with the precipitation of the omega-phase. These discs formed both randomly within the matrix and heterogeneously along dislocations and at grain boundaries

Pulsed laser deposition to synthesize the bridge structure of artificial nacre: Comparison of nano- and femtosecond lasers

Science.gov (United States)

Melaibari, Ammar A.; Molian, Pal

2012-11-01

Nature offers inspiration to new adaptive technologies that allow us to build amazing shapes and structures such as nacre using synthetic materials. Consequently, we have designed a pulsed laser ablation manufacturing process involving thin film deposition and micro-machining to create hard/soft layered "brick-bridge-mortar" nacre of AlMgB14 (hard phase) with Ti (soft phase). In this paper, we report pulsed laser deposition (PLD) to mimic brick and bridge structures of natural nacre in AlMgB14. Particulate formation inherent in PLD is exploited to develop the bridge structure. Mechanical behavior analysis of the AlMgB14/Ti system revealed that the brick is to be 250 nm thick, 9 μm lateral dimensions while the bridge (particle) is to have a diameter of 500 nm for a performance equivalent to natural nacre. Both nanosecond (ns) and femtosecond (fs) pulsed lasers were employed for PLD in an iterative approach that involves varying pulse energy, pulse repetition rate, and target-to-substrate distance to achieve the desired brick and bridge characteristics. Scanning electron microscopy, x-ray photoelectron spectroscopy, and optical profilometer were used to evaluate the film thickness, particle size and density, stoichiometry, and surface roughness of thin films. Results indicated that both ns-pulsed and fs-pulsed lasers produce the desired nacre features. However, each laser may be chosen for different reasons: fs-pulsed laser is preferred for much shorter deposition time, better stoichiometry, uniform-sized particles, and uniform film thickness, while ns-pulsed laser is favored for industrial acceptance, reliability, ease of handling, and low cost.

Control of ultrafast pulse propagation in semiconductor components

DEFF Research Database (Denmark)

Poel, Mike van der; Hansen, Per Lunnemann; Mørk, Jesper

2009-01-01

Time shifting of optical pulses with duration in the range from 100 fs to a few ps represents one extreme of slow light, where THz bandwidth for the slow down or speed up is necessary. The physics of the time shifting of such very short pulses involves the gain saturation of the optical medium...... and is different from the slow-light mechanisms responsible for time shifting of pulses of narrower bandwidth. Experimental and theoretical results with semiconductor components are presented, emphasizing the physics as well as the limitations imposed by the dynamical processes....

High magnetic ordering temperature in the perovskites Sr{sub 4-x}La{sub x}Fe{sub 3}ReO{sub 12} (x=0.0, 1.0, 2.0)

Energy Technology Data Exchange (ETDEWEB)

Retuerto, M.; Li, M.-R.; Go, Y.B. [Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ 08854 (United States); Ignatov, A.; Croft, M. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Ramanujachary, K.V. [Department of Chemistry and Physics, Rowan University, 210 Mullica Hill Road, Glassboro, NJ 08028 (United States); Herber, R.H.; Nowik, I. [Racah Institute of Physics, Hebrew University, Jerusalem, 91904 Israel (Israel); Hodges, J.P. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Dachraoui, W.; Hadermann, J. [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Greenblatt, M., E-mail: martha@rutchem.rutgers.edu [Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ 08854 (United States)

2012-10-15

A series of perovskites Sr{sub 4-x}La{sub x}Fe{sub 3}ReO{sub 12} (x=0.0, 1.0, 2.0) has been prepared by wet chemistry methods. The structure analyses by powder X-ray and neutron diffraction and electron microscopy show that these compounds adopt simple perovskite structures without cation ordering over the B sites: tetragonal (I4/mcm) for x=0.0 and 1.0 and orthorhombic (Pbmn) for x=2.0. The oxidation states of the cations in the compound with x=0.0 appear to be Fe{sup 3+/4+} and Re{sup 7+} and decrease for both with La substitution as evidenced by X-ray absorption spectroscopy. All the compounds are antiferromagnetically ordered above room temperature, as demonstrated by Moessbauer spectroscopy and the magnetic structures, which were determined by powder neutron diffraction. The substitution of Sr by La strongly affects the magnetic properties with an increase of T{sub N} up to {approx}750 K. - Graphical abstract: High resolution transmission electron microscopy image of Sr{sub 4-x}La{sub x}Fe{sub 3}ReO{sub 12} (x=2.0), showing twin domains. Fourier transforms are given of the areas indicated by the circles. Highlights: Black-Right-Pointing-Pointer Sr{sub 4-x}La{sub x}Fe{sub 3}ReO{sub 12} (x=0.0, 1.0, 2.0) perovskites prepared by wet chemistry. Black-Right-Pointing-Pointer PXD, PND, ED, indicate no cation ordering, I4/mcm) for x=0.0, 1.0, Pbmn for x=2. Black-Right-Pointing-Pointer XAS show oxidation states Fe{sup 3+/4+} and Re{sup 7+}; both decrease with increasing x. Black-Right-Pointing-Pointer All order antiferromagnetically above RT, with highest T{sub N} {approx}750 K.

The analysis of low-energy ion from a gas-puff laser plasma. The observation of ablated particles from the silicon irradiated with a fs laser

International Nuclear Information System (INIS)

Azuma, Hirozumi; Kamiya, Nobuyuki; Takeuchi, Akihiro; Ito, Tadashi; Suzuki, Noritomo; Daido, Hiroyuki; Mori, Michiaki; Ogura, Kouichi; Sagisaka, Akito; Orimo, Satoshi; Hayashi, Yukio; Hazama, Hisanao

2005-01-01

The single-shot creation of tadpolelike silicon nanoparticles constructed with multi-crystalline heads and amorphous tails by a high brightness fs-pulse laser was demonstrated. This is also the first demonstration of the creation of a nanosized connection of multicrystalline silicon with amorphous silicon. This result should expand the creation of new materials by a laser ablation using a high-intensity fs laser, and the created silicon nanoparticles can be applied to scientific and industrial fields. (author)

Photoemission studies using femtosecond pulses for high brightness electron beams

International Nuclear Information System (INIS)

Srinivasan-Rao, T.; Tsang, T.; Fischer, J.

1990-06-01

We present the results of a series of experiments where various metal photocathodes are irradiated with ultrashort laser pulses, whose characteristics are: λ = 625 nm, τ = 100 fs, PRR = 89.5 MHz, Hν = 2 eV and average power 25 mW in each of the two beams. The quantum efficiency of the metals range from ∼10 -12 to 10 -8 at a power density of 100 MW/cm 2 at normal incidence. Since all the electrons are emitted due to multiphoton processes, these efficiencies are expected to increase substantially at large intensities. The efficiency at 100 MW/cm 2 has been increased by using p-polarized light at oblique incidence by ∼20x and by mediating the electron emission through surface plasmon excitation by ∼10 3 x. For the low intensities used in these experiments, the electron pulse duration is almost the same as the laser pulse duration for both the bulk and the surface plasmon mediated photoemission. 7 refs., 8 figs., 2 tabs

Magnetoimpedance studies on urine treated Co{sub 66}Ni{sub 7}Si{sub 7}B{sub 20} ribbons

Energy Technology Data Exchange (ETDEWEB)

Kotagiri, Ganesh [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Markandeyulu, G., E-mail: mark@iitm.ac.in [Advanced Magnetic Materials Laboratory, Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Doble, Mukesh; Nandakumar, V. [Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036 (India)

2015-11-15

Magnetoimpedance (MI) response of Co{sub 66}Ni{sub 7}Si{sub 7}B{sub 20} ribbons treated with artificial urine with protein bovine serum albumin (BSA), artificial urine without protein BSA and healthy male urine was studied as a function of time of incubation. The maximum MI [(MI){sub m}] values of the ribbons treated with artificial urine without protein (RTAU) after 3 h, 6 h, 12 h and 24 h of incubation are 30% (at 4 MHz), 15% (at 5 MHz), 14% (at 10 MHz) and 8% (at 13 MHz) respectively. On the other hand, the respective (MI){sub m} values of the ribbons treated with artificial urine with protein (RTAUP) are 33% (at 4 MHz), 25% (at 5 MHz), 20% (at 8 MHz) and 15% (12 MHz). However (MI){sub m} values of the ribbons treated with healthy male urine (RTHMU) after 4 h, 5 h, 10 h and 15 h of incubation are 71% (at 3 MHz), 57% (at 3 MHz), 25% (at 6 MHz) and 25% (at 5 MHz), respectively. The saturation magnetization (M{sub s}) values of RTAU after 3 h, 6 h, 12 h and 24 h of incubation are 71 emu/g, 65 emu/g, 63 emu/g and 60 emu/g respectively whereas, the respective M{sub s} values of RTAUP are 73 emu/g, 69 emu/g, 67 emu/g and 64 emu/g. The M{sub s} values of RTHMU after 4 h, 5 h, 10 h and 15 h of incubation are 96 emu/g, 90 emu/g, 75 emu/g and 75 emu/g respectively. The decrease in M{sub s} and (MI){sub m} values in RTAU and RTAUP compared to as-quenched ribbon is related to the amounts of various elements etched out from the ribbons and increased surface roughness. The M{sub s} and (MI){sub m} values of RTHMU are seen to have increased after 4 h and 5 h of incubation, due to strain relaxation through removal of strain developed during rapid quenching of the ribbons. On the other hand, the M{sub s} and (MI){sub m} values of RTHMU after 10 h and 15 h have decreased due to deterioration of the surface of the ribbons and thus, increase in magnetic (surface) anisotropy. The decrease in (MI){sub m} and M{sub S} of RTAU with the time of incubation are more rapid compared to that

Influence of pulse width and target density on pulsed laser deposition of thin YBaCuO film

International Nuclear Information System (INIS)

Vikram, S.

1999-01-01

We have studied the effects of temporal pulse width and target density on the deposition of thin films of YBaCuO. A 248nm excimer laser and an 825nm Ti-sapphire laser were used to conduct the experiments with pulse widths of 27 ns, 16 ns, and 150 fs, and target densities of 80% and 90%. Scanning electron microscope photomicrographs and profilometer traces show a striking difference between nanosecond and femtosecond laser irradiation. Shortening the pulse width reduced particulate formation, provided stoichiometry, and improved the film properties. Decreasing the target density raised the ablation rate, produced thicker but nonuniform films, and reduced particulate formation

Influence of pulse width and target density on pulsed laser deposition of thin YBaCuO film.

Energy Technology Data Exchange (ETDEWEB)

Vikram, S.

1999-01-20

We have studied the effects of temporal pulse width and target density on the deposition of thin films of YBaCuO. A 248nm excimer laser and an 825nm Ti-sapphire laser were used to conduct the experiments with pulse widths of 27 ns, 16 ns, and 150 fs, and target densities of 80% and 90%. Scanning electron microscope photomicrographs and profilometer traces show a striking difference between nanosecond and femtosecond laser irradiation. Shortening the pulse width reduced particulate formation, provided stoichiometry, and improved the film properties. Decreasing the target density raised the ablation rate, produced thicker but nonuniform films, and reduced particulate formation.

Improvement in R{sub off}/R{sub on} ratio and reset current via combining compliance current with multilayer structure in tantalum oxide-based RRAM

Energy Technology Data Exchange (ETDEWEB)

Chen, Xiaorong; Feng, Jie [Shanghai Jiao Tong University, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Department of Micro/Nano Electronics, Shanghai (China)

2015-07-15

Improvements in the R{sub off}/R{sub on} ratio and reset current are required prior to the practical application of RRAM. To achieve this improvement, tantalum oxide-based RRAM devices with multilayer structure (bi-layer and tri-layer) were fabricated and various compliance currents were adopted. The reset current of 40 μA was observed; the R{sub off}/R{sub on} ratio increased to more than 20 in the tri-layer structure device. Resistance changes in two types of devices under voltage pulses with different pulse width were also conducted. The tri-layer device exhibited lower reset voltage and higher R{sub off}/R{sub on} ratio than the bi-layer device under voltage pulses. X-ray photoelectron spectroscopy demonstrated the formation of Ta{sub 2}O{sub 5} via plasma oxidation, and there was an oxygen gradient in the multilayer devices. The results demonstrated that the tri-layer structure with oxygen gradient was an effective method for achieving better device performance. Additionally, it is implied that reasonable control of the proportion of TaO{sub 2} and Ta{sub 2}O{sub 5} and compliance current can improve device performance. (orig.)

Pressure Monitoring Using Hybrid fs/ps Rotational CARS

Science.gov (United States)

Kearney, Sean P.; Danehy, Paul M.

2015-01-01

We investigate the feasibility of gas-phase pressure measurements at kHz-rates using fs/ps rotational CARS. Femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is then probed by a high-energy 6-ps pulse introduced at a time delay from the Raman preparation. Rotational CARS spectra were recorded in N2 contained in a room-temperature gas cell for pressures from 0.1 to 3 atm and probe delays ranging from 10-330 ps. Using published self-broadened collisional linewidth data for N2, both the spectrally integrated coherence decay rate and the spectrally resolved decay were investigated as means for detecting pressure. Shot-averaged and single-laser-shot spectra were interrogated for pressure and the accuracy and precision as a function of probe delay and cell pressure are discussed. Single-shot measurement accuracies were within 0.1 to 6.5% when compared to a transducer values, while the precision was generally between 1% and 6% of measured pressure for probe delays of 200 ps or more, and better than 2% as the delay approached 300 ps. A byproduct of the pressure measurement is an independent but simultaneous measurement of the gas temperature.

Enhancement of ferromagnetism in BaFeO{sub 3}-KTa{sub 0.47}Nb{sub 0.53}O{sub 3} multilayers compared to pseudo-cubic BaFeO{sub 3} thin film grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Cianfrone, Joe; Kim, Seonhoo; Kim, Kyeong-Won; Norton, David [Department of Materials Science and Engineering, University of Florida, Gainesville, FL (United States); Ghosh, Siddhartha; Hebard, Arthur F. [Department of Physics, University of Florida, Gainesville, FL (United States)

2017-06-15

Oxide multilayer hetero-structure of BaFeO{sub 3}-KTa{sub 0.47}Nb{sub 0.53}O{sub 3} have been grown using the pulsed laser deposition and the ex situ annealed in a flowing oxygen atmosphere. The multilayer has been characterized using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Magnetic properties have been studied via SQUID measurements. Magnetization in the multilayer structure shows significant improvement compared to previous measurements of bare BaFeO{sub 3}. Measuring magnetization as a function of temperature and fitting the resulting M-T curves to Bloch's 3/2 law, yields an estimated Curie temperature (T{sub C}) of around 425 K and a P factor of around 1.5, consistent with magnetization from a three dimensional crystal structure. In spite of using a room temperature ferroelectric KTa{sub 0.47}Nb{sub 0.53}O{sub 3} composition, no evidence of ferroelectricity was observed in multi-layer structure. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Hydrophobic treatment on polymethylmethacrylate surface by nanosecond-pulse DBDs in CF{sub 4} at atmospheric pressure

Energy Technology Data Exchange (ETDEWEB)

Zhang, Cheng [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Yang [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Shao, Tao, E-mail: st@mail.iee.ac.cn [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China); Xie, Qing [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Baoding 071003 (China); Xu, Jiayu [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Wenjin [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Power Electronics and Electric Drive, Chinese Academy of Sciences, Beijing 100190 (China)

2014-08-30

Highlights: • Increase in hydrophobicity on PMMA is achieved after the DBD treatment in CF{sub 4}, and the water contact angle can increase from 68° to 100° after treatment. • Nanosecond-pulse DBD is used for the surface treatment and the power density is about 114.8 mW/cm{sup 2}. • The effects of applied voltage, CF{sub 4} flow, and time on plasma treatment are investigated. • Plasma treatment causes morphological change, significantly increases the roughness of the surface, and introduces fluorine-containing groups into the polymethylmethacrylate surface. • Hydrophobic behavior of the treated PMMA surface is slightly affected by the aging effect. - Abstract: Nanosecond-pulse dielectric barrier discharge (DBD) can provide non-thermal plasmas with extremely high energy and high density, which can result in a series of complicated physical and chemical reactions in the surface treatment of polymers. Therefore, in this paper, hydrophobic treatment of polymethylmethacrylate (PMMA) surface is conducted by nanosecond-pulse DBD in carbon tetrafluoride (CF{sub 4}) at atmospheric pressure. Investigations on surface morphology and chemical composition before and after the DBD treatment in CF{sub 4} are conducted with the contact angle measurement, atomic force microscope, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer. The effects of the applied voltage, CF{sub 4} flow rate, and treatment time on the hydrophobic modification are studied. Results show that the contact angles of the treated PMMA surface increases with the applied voltage, and it could be greatly affected by the CF{sub 4} flow rate and the treatment time. The water contact angle can increase from 68° to 100° after the treatment. Furthermore, both surface morphology and chemical composition of the PMMA samples are changed. Both the increase of the surface roughness and the occurrence of fluorine-containing functional groups on the PMMA surface treated by DBD in CF{sub

Preparation of TiO sub 2 nanoparticles by pulsed laser ablation: Ambient pressure dependence of crystallization

CERN Document Server

Matsubara, M; Yamaki, T; Itoh, H; Abe, H

2003-01-01

Pulsed laser ablation (PLA) with a KrF excimer laser was used to prepare fine particles of titanium dioxide (TiO sub 2). The ablation in an atmosphere of Ar and O sub 2 (5:5) at total pressures of >= 1 Torr led to the formation of TiO sub 2 nanoparticles composed of anatase and rutile structures without any suboxides. The weight fraction of the rutile/anatase crystalline phases was dependent on the pressure of the Ar/O sub 2 gas. The TiO sub 2 nanoparticles had a spherical shape and their size, ranging from 10 and 14 nm, also appeared to be dependent on the ambient pressure. (author)

Refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films by multiple femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Lei, Kai; Wang, Yang, E-mail: ywang@siom.ac.cn; Jiang, Minghui; Wu, Yiqun [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2016-05-07

In this study, the controllable effective refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

Influence of the oxygen pressure on the preferred orientation and optical properties of the pulsed-laser deposited Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4±δ} thin films

Energy Technology Data Exchange (ETDEWEB)

Kong, Wenwen [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Gao, Bo [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Jiang, Chunping, E-mail: cpjiang2008@sinano.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics of CAS, Suzhou 215123 (China); Chang, Aimin, E-mail: changam@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China)

2015-11-25

Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4±δ} (MCN) thin films with different oxygen pressures (in the range of 2 × 10{sup −4} to 2 Pa) are prepared on Si(100)/SiO{sub x} substrates by pulsed laser deposition technique. Effects of oxygen pressures on the microstructure and optical properties of the prepared thin films are investigated in detail. The grain sizes of films gradually decrease and the preferential orientation of the MCN films change from (400) to (113) as the oxygen pressure increases. The x-ray photoelectron spectroscopy results show that the composition of these films is proximity to that of the bulk material. In addition, the Mn{sup 3+}/Mn{sup 4+} pairs increase with an increase in the oxygen pressures increase. From spectroscopic ellipsometer spectroscopy, it is found that both the refractive index n and extinction coefficient k of the (400)-oriented films have no obvious peaks, whereas in the (113)-oriented films, peaks are exist. This feature typically originates from a change in the crystal structure as oxygen pressures increase. Furthermore, the Raman active mode (around ca. 650 cm{sup −1}) of (400) films almost disappears, whilst the active mode in (113) films remain. - Highlights: • The Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4-δ} (MCN) spinel films are deposited by pulsed laser deposition process at different oxygen pressures. • The preferential orientation of the films changes from (400) plane to (113) as the oxygen pressure increases. • The E{sub g} of the (113) film is twice as large as that of the (400) film. • The Raman active mode (around ca. 650 cm{sup −1}) can be observed in the (113) films while not in the (400) film.

Optical synchronization of a free-electron laser with femtosecond precision

International Nuclear Information System (INIS)

Loehl, F.

2009-09-01

High-gain free-electron lasers (FELs) are capable of generating sub-10 fs long light pulses. In order to take full advantage of these extremely short light pulses in time-resolved experiments, synchronization with a so far unprecedented timing accuracy is required. Within this thesis, an optical synchronization system providing sub-10 fs stability has been developed and was implemented at the ultra-violet and soft X-ray free-electron laser FLASH at DESY, Hamburg. The system uses a mode-locked laser as a timing reference. The laser pulses are distributed via length stabilized optical fiber-links to the remote locations. A key feature of the system is a bunch arrival-time monitor detecting the electron bunch arrival-time with an unrivaled resolution of 6 fs. A feedback system based on the arrival-time monitor was established, improving the arrival-time fluctuations from 200 fs in the unstabilized case to 25 fs with active feedback. In order to achieve the high peak current of several thousand amperes required for the FEL process, the electron bunches are longitudinally compressed in two magnetic chicanes. A second feedback system was developed stabilizing the bunch compression process based on measurements of diffraction radiation. The combination of both feedback systems improves the stability of the FEL radiation significantly. (orig.)

Optical synchronization of a free-electron laser with femtosecond precision

Energy Technology Data Exchange (ETDEWEB)

Loehl, F.

2009-09-15

High-gain free-electron lasers (FELs) are capable of generating sub-10 fs long light pulses. In order to take full advantage of these extremely short light pulses in time-resolved experiments, synchronization with a so far unprecedented timing accuracy is required. Within this thesis, an optical synchronization system providing sub-10 fs stability has been developed and was implemented at the ultra-violet and soft X-ray free-electron laser FLASH at DESY, Hamburg. The system uses a mode-locked laser as a timing reference. The laser pulses are distributed via length stabilized optical fiber-links to the remote locations. A key feature of the system is a bunch arrival-time monitor detecting the electron bunch arrival-time with an unrivaled resolution of 6 fs. A feedback system based on the arrival-time monitor was established, improving the arrival-time fluctuations from 200 fs in the unstabilized case to 25 fs with active feedback. In order to achieve the high peak current of several thousand amperes required for the FEL process, the electron bunches are longitudinally compressed in two magnetic chicanes. A second feedback system was developed stabilizing the bunch compression process based on measurements of diffraction radiation. The combination of both feedback systems improves the stability of the FEL radiation significantly. (orig.)

Effect of radiation damping on the interaction of ultra-intense laser pulses with an overdense plasma