Radial Growth of Self-Catalyzed GaAs Nanowires and the Evolution of the Liquid Ga-Droplet Studied by Time-Resolved in Situ X-ray Diffraction.

Science.gov (United States)

Schroth, Philipp; Jakob, Julian; Feigl, Ludwig; Mostafavi Kashani, Seyed Mohammad; Vogel, Jonas; Strempfer, Jörg; Keller, Thomas F; Pietsch, Ullrich; Baumbach, Tilo

2018-01-10

We report on a growth study of self-catalyzed GaAs nanowires based on time-resolved in situ X-ray structure characterization during molecular-beam-epitaxy in combination with ex situ scanning-electron-microscopy. We reveal the evolution of nanowire radius and polytypism and distinguish radial growth processes responsible for tapering and side-wall growth. We interpret our results using a model for diameter self-stabilization processes during growth of self-catalyzed GaAs nanowires including the shape of the liquid Ga-droplet and its evolution during growth.

In situ determination of the depuration of three- and four-ringed polycyclic aromatic hydrocarbons co-adsorbed onto mangrove leaf surfaces

International Nuclear Information System (INIS)

Sun, Haifeng; Shi, Jing; Guo, Shuai; Zhang, Yong; Duan, Lusha

2016-01-01

A dual-wavelength fiber-optic fluorimetry for the in situ simultaneous determinations of fluorene (Flu), phenanthrene (Phe) and pyrene (Pyr) adsorbed onto the leaf surfaces of living Avicennia marina (Am) seedling were developed and used to study the depuration kinetics of the three PAHs, adsorbed individually or mixed together, onto living Am leaf surfaces. Limits of detection for the in situ measurements of adsorbed Flu, Phe and Pyr were 4.62, 2.75 and 1.38 ng spot"−"1, respectively. The depuration kinetics of the three selected polycyclic aromatic hydrocarbons (PAHs) are divided into rapid and slow phases; both phases followed the same first-order kinetics with relative clearance rates of Flu > Phe > Pyr during the rapid phase, and a clearance rate order of Pyr > Flu > Phe during the slow phase. For the three PAHs co-adsorbed on living Am leaf surfaces, a significant synergistic effect was detected during the rapid phase clearance; conversely, an antagonistic effect was observed during the slow phase. However, the synergistic effect dominated during both phases of the depuration process, and the co-adsorption of PAHs promoted the clearance of all three compounds from the mangrove leaf surfaces. These findings demonstrate a novel analytical method for in situ characterization of multiple PAHs adsorbed onto the plant surfaces. - Highlights: • A novel method for the in situ determination of multi-component PAHs was developed. • Synergistic and antagonistic effects separately occurred over rapid and slow phases. • The clearance of all three PAHs from leaf surfaces was promoted by co-adsorption. - The co-adsorption of PAHs promoted the depuration of all three compounds from the mangrove leaf surfaces.

Multiple-reflection time-of-flight mass spectrometry for in situ applications

Science.gov (United States)

Dickel, T.; Plaß, W. R.; Lang, J.; Ebert, J.; Geissel, H.; Haettner, E.; Jesch, C.; Lippert, W.; Petrick, M.; Scheidenberger, C.; Yavor, M. I.

2013-12-01

Multiple-reflection time-of-flight mass spectrometers (MR-TOF-MS) have recently been installed at different low-energy radioactive ion beam facilities. They are used as isobar separators with high ion capacity and as mass spectrometers with high mass resolving power and accuracy for short-lived nuclei. Furthermore, MR-TOF-MS have a huge potential for applications in other fields, such as chemistry, biology, medicine, space science, and homeland security. The development, commissioning and results of an MR-TOF-MS is presented, which serves as proof-of-principle to show that very high mass resolving powers (∼105) can be achieved in a compact device (length ∼30 cm). Based on this work, an MR-TOF-MS for in situ application has been designed. For the first time, this device combines very high mass resolving power (>105), mobility, and an atmospheric pressure inlet in one instrument. It will enable in situ measurements without sample preparation at very high mass accuracy. Envisaged applications of this mobile MR-TOF-MS are discussed.

Dehydrogenation kinetics of pure and nickel-doped magnesium hydride investigated by in situ time-resolved powder X-ray diffraction

DEFF Research Database (Denmark)

Jensen, T.R.; Andreasen, A.; Vegge, Tejs

2006-01-01

The dehydrogenation kinetics of pure and nickel (Ni)-doped (2w/w%) magnesium hydride (MgH2) have been investigated by in situ time-resolved powder X-ray diffraction (PXD). Deactivated samples, i.e. air exposed, are investigated in order to focus on the effect of magnesium oxide (MgO) surface layers......, which might be unavoidable for magnesium (Mg)-based storage media for mobile applications. A curved position-sensitive detector covering 120 degrees in 20 and a rotating anode X-ray source provide a time resolution of 45 s and up to 90 powder pattems collected during an experiment under isothermal...... by the Johnson-Mehi-Avrami formalism in order to derive rate constants at different temperatures. The apparent activation energies for dehydrogenation of pure and Ni-doped magnesium hydride were E-A approximate to 300 and 250 kJ/mol, respectively. Differential scanning calorimetry gave, E-A = 270 k...

Early stages of spinodal decomposition in Fe-Cr resolved by in-situ small-angle neutron scattering

Science.gov (United States)

Hörnqvist, M.; Thuvander, M.; Steuwer, A.; King, S.; Odqvist, J.; Hedström, P.

2015-02-01

In-situ, time-resolved small-angle neutron scattering (SANS) investigations of the early stages of the spinodal decomposition process in Fe-35Cr were performed at 773 and 798 K. The kinetics of the decomposition, both in terms of characteristic distance and peak intensity, followed a power-law behaviour from the start of the heat treatment (a'= 0.10-0.11 and a″ = 0.67-0.86). Furthermore, the method allows tracking of the high-Q slope, which is a sensitive measure of the early stages of decomposition. Ex-situ SANS and atom probe tomography were used to verify the results from the in-situ investigations. Finally, the in-situ measurement of the evolution of the characteristic distance at 773 K was compared with the predictions from the Cahn-Hilliard-Cook model, which showed good agreement with the experimental data (a'= 0.12-0.20 depending on the assumed mobility).

Cation Movements during Dehydration and NO2 Desorption in a Ba-Y,FAU zeolite: an in situ Time-resolved X-ray Diffraction Study

Energy Technology Data Exchange (ETDEWEB)

Wang, Xianqin; Hanson, Jonathan C.; Kwak, Ja Hun; Szanyi, Janos; Peden, Charles HF

2013-02-28

Synchrotron-based in situ time-resolved X-ray diffraction and Rietveld analysis were used to probe the interactions between BaY, FAU zeolite frameworks and H2O or NO2 molecules. These results provided information about the migration of the Ba2+ cations in the zeolite framework during dehydration and during NO2 adsorption/desorption processes in a water free zeolite. In the hydrated structure water molecules form four double rings of hexagonal ice-like clusters [(H2O)6] in the 12-ring openings of the super-cage. These water rings interacted with the cations and the zeolite framework through four cation/water clusters centered over the four 6-membered rings of the super-cage (site II). Interpenetrating tetrahedral water clusters [(H2O)4] and tetrahedral Ba+2 cation clusters were observed in the sodalite cage. Consistent with the reported FT-IR results, three different ionic NOx species (NO+, NO+-NO2, and NO3-) were observed following NO2 adsorption by the dehydrated Ba-Y,FAU zeolite. The structure of the water and the NOx species were correlated with the interactions between the adsorbates, the cations, and the framework. The population of Ba2+ ions at different cationic positions strongly depended on the amount of bound water or NOx species. Both dehydration and NO2 adsorption/desorption resulted in facile migration of Ba2+ ions among the different cationic positions. Data obtained in this work have provided direct evidence for the Ba2+ cation migration to accommodate the binding of gas molecules. This important feature may play a pivotal role in the strong binding of NO2 to Ba-Y,FAU zeolite, a prerequisite for high catalytic activity in lean NOx reduction catalysis.

Fast time-resolved aerosol collector: proof of concept

Science.gov (United States)

Yu, X.-Y.; Cowin, J. P.; Iedema, M. J.; Ali, H.

2010-10-01

Atmospheric particles can be collected in the field on substrates for subsequent laboratory analysis via chemically sensitive single particle methods such as scanning electron microscopy with energy dispersive x-ray analysis. With moving substrates time resolution of seconds to minutes can be achieved. In this paper, we demonstrate how to increase the time resolution when collecting particles on a substrate to a few milliseconds to provide real-time information. Our fast time-resolved aerosol collector ("Fast-TRAC") microscopically observes the particle collection on a substrate and records an on-line video. Particle arrivals are resolved to within a single frame (4-17 ms in this setup), and the spatial locations are matched to the subsequent single particle analysis. This approach also provides in-situ information on particle size and number concentration. Applications are expected in airborne studies of cloud microstructure, pollution plumes, and surface long-term monitoring.

Early stages of spinodal decomposition in Fe–Cr resolved by in-situ small-angle neutron scattering

International Nuclear Information System (INIS)

Hörnqvist, M.; Thuvander, M.; Steuwer, A.; King, S.; Odqvist, J.; Hedström, P.

2015-01-01

In-situ, time-resolved small-angle neutron scattering (SANS) investigations of the early stages of the spinodal decomposition process in Fe–35Cr were performed at 773 and 798 K. The kinetics of the decomposition, both in terms of characteristic distance and peak intensity, followed a power-law behaviour from the start of the heat treatment (a′   = 0.10–0.11 and a″ = 0.67–0.86). Furthermore, the method allows tracking of the high–Q slope, which is a sensitive measure of the early stages of decomposition. Ex-situ SANS and atom probe tomography were used to verify the results from the in-situ investigations. Finally, the in-situ measurement of the evolution of the characteristic distance at 773 K was compared with the predictions from the Cahn-Hilliard-Cook model, which showed good agreement with the experimental data (a′   = 0.12–0.20 depending on the assumed mobility)

Early stages of spinodal decomposition in Fe–Cr resolved by in-situ small-angle neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Hörnqvist, M., E-mail: magnus.hornqvist@chalmers.se; Thuvander, M. [Department of Applied Physics, Chalmers University of Technology, Fysikgränd 3, S-412 96 Gothenburg (Sweden); Steuwer, A. [MAX IV Laboratory, Lund University, S-221 00 Lund (Sweden); Nelson Mandela Metropolitan University, Gardham Ave., Port Elizabeth 6031 (South Africa); King, S. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX Didcot (United Kingdom); Odqvist, J.; Hedström, P. [Materials Science and Engineering, KTH Royal Institute of Technology, Brinellvägen 23, S-100 44 Stockholm (Sweden)

2015-02-09

In-situ, time-resolved small-angle neutron scattering (SANS) investigations of the early stages of the spinodal decomposition process in Fe–35Cr were performed at 773 and 798 K. The kinetics of the decomposition, both in terms of characteristic distance and peak intensity, followed a power-law behaviour from the start of the heat treatment (a′{sup  }= 0.10–0.11 and a″ = 0.67–0.86). Furthermore, the method allows tracking of the high–Q slope, which is a sensitive measure of the early stages of decomposition. Ex-situ SANS and atom probe tomography were used to verify the results from the in-situ investigations. Finally, the in-situ measurement of the evolution of the characteristic distance at 773 K was compared with the predictions from the Cahn-Hilliard-Cook model, which showed good agreement with the experimental data (a′{sup  }= 0.12–0.20 depending on the assumed mobility)

Novel thermosyphon driven hydrothermal flow-through cell for in situ and time resolved neutron diffraction studies

International Nuclear Information System (INIS)

Xia, Fang; Qian, Gujie; Etschmann, Barbara; University of Adelaide, South Australia, Australia; University of Adelaide, South Australia, Australia; Studer, Andrew; Olsen, Scott

2009-01-01

Full text: A flow-through cell for hydrothermal phase transformation studies by in situ and time-resolved neutron diffraction has been designed and constructed. The cell has a large internal volume of 320 m L and can work at up to 300 degree Centigrade under autogeneous vapour pressures (-85 bar). The fluid flow is driven by thermosyphon which is realized by the proper design of temperature difference around the closed loop[1,2). The main body of the cell is made of stainless steel (316 type), but the sample compartment is constructed from non-scattering Ti/Zr alloy. We have successfully commissioned the cell on Australia's new high intensity powder diffractometer WOMBAT in ANSTO, using a simple transformation reaction from leucite (KAISi 2 O 6 ) to analcime (NaAISi 2 O 6H2O ) and then back from analcime to leucite. The demonstration proved that the cell is an excellent tool for probing hydrothermal phase transformations. By collecting diffraction data every 5 min, it was clearly seen that leucite was progressively transformed to analcime in a NaCI solution, and the produced analcime was progressively transformed back to leucite in a K 2 CO 3 solution.

Time-resolved spectroscopy in synchrotron radiation

International Nuclear Information System (INIS)

Rehn, V.; Stanford Univ., CA

1980-01-01

Synchrotron radiation (SR) from large-diameter storage rings has intrinsic time structure which facilitates time-resolved measurements form milliseconds to picoseconds and possibly below. The scientific importance of time-resolved measurements is steadily increasing as more and better techniques are discovered and applied to a wider variety of scientific problems. This paper presents a discussion of the importance of various parameters of the SR facility in providing for time-resolved spectroscopy experiments, including the role of beam-line optical design parameters. Special emphasis is placed on the requirements of extremely fast time-resolved experiments with which the effects of atomic vibrational or relaxation motion may be studied. Before discussing the state-of-the-art timing experiments, we review several types of time-resolved measurements which have now become routine: nanosecond-range fluorescence decay times, time-resolved emission and excitation spectroscopies, and various time-of-flight applications. These techniques all depend on a short SR pulse length and a long interpulse period, such as is provided by a large-diameter ring operating in a single-bunch mode. In most cases, the pulse shape and even the stability of the pulse shape is relatively unimportant as long as the pulse length is smaller than the risetime of the detection apparatus, typically 1 to 2 ns. For time resolution smaller than 1 ns, the requirements on the pulse shape become more stringent. (orig./FKS)

XRMON-GF: A novel facility for solidification of metallic alloys with in situ and time-resolved X-ray radiographic characterization in microgravity conditions

Science.gov (United States)

Nguyen-Thi, H.; Reinhart, G.; Salloum Abou Jaoude, G.; Mathiesen, R. H.; Zimmermann, G.; Houltz, Y.; Voss, D.; Verga, A.; Browne, D. J.; Murphy, A. G.

2013-07-01

As most of the phenomena involved during the growth of metallic alloys from the melt are dynamic, in situ and time-resolved X-ray imaging should be retained as the method of choice for investigating the solidification front evolution. On Earth, the gravity force is the major source of various disturbing effects (natural convection, buoyancy/sedimentation, and hydrostatic pressure) which can significantly modify or mask certain physical mechanisms. Therefore solidification under microgravity is an efficient way to eliminate such perturbations to provide unique benchmark data for the validation of models and numerical simulations. Up to now, in situ observation during microgravity solidification experiments were limited to the investigations on transparent organic alloys, using optical methods. On the other hand, in situ observation on metallic alloys generally required synchrotron facilities. This paper reports on a novel facility we have designed and developed to investigate directional solidification on metallic alloys in microgravity conditions with in situ X-ray radiography observation. The facility consists of a Bridgman furnace and an X-ray radiography device specifically devoted to the study of Al-based alloys. An unprecedented experiment was recently performed on board a sounding rocket, with a 6 min period of microgravity. Radiographs were successfully recorded during the entire experiment including the melting and solidification phases of the sample, with a Field-of-View of about 5 mm×5 mm, a spatial resolution of about 4 µm and a frequency of 2 frames per second. Some preliminary results are presented on the solidification of the Al-20 wt% Cu sample, which validate the apparatus and confirm the potential of in situ X-ray characterization for the investigation of dynamical phenomena in materials processing, and particularly for the studying of metallic alloys solidification.

SERS and in situ SERS spectroscopy of riboflavin adsorbed on silver, gold and copper substrates. Elucidation of variability of surface orientation based on both experimental and theoretical approach

Science.gov (United States)

Dendisová-Vyškovská, Marcela; Kokaislová, Alžběta; Ončák, Milan; Matějka, Pavel

2013-04-01

Surface-enhanced Raman scattering and in situ surface-enhanced Raman scattering spectra have been collected to study influences of (i) used metal and (ii) applied electrode potential on orientation of adsorbed riboflavin molecules. Special in situ SERS spectroelectrochemical cell was used to obtain in situ SERS spectra of riboflavin adsorbed on silver, gold and copper nanostructured surfaces. Varying electrode potential was applied in discrete steps forming a cycle from positive values to negative and backward. Observed spectral features in in situ SERS spectra, measured at alternate potentials, have been changing very significantly and the spectra have been compared with SERS spectra of riboflavin measured ex situ. Raman spectra of single riboflavin molecule in the vicinity to metal (Ag, Au and Cu) clusters have been calculated for different mutual positions. The results demonstrate significant changes of bands intensities which can be correlated with experimental spectra measured at different potentials. Thus, the orientation of riboflavin molecules adsorbed on metal surfaces can be elucidated. It is influenced definitely by the value of applied potential. Furthermore, the riboflavin adsorption orientation on the surface depends on the used metal. Adsorption geometries on the copper substrates are more diverse in comparison with the orientations on silver and gold substrates.

In situ distributed diagnostics of flowable electrode systems: resolving spatial and temporal limitations.

Science.gov (United States)

Dennison, C R; Gogotsi, Y; Kumbur, E C

2014-09-14

In this study, we have developed an in situ distributed diagnostics tool to investigate spatial and temporal effects in electrochemical systems based on flowable electrodes. Specifically, an experimental approach was developed that enables spatially-resolved voltage measurements to be obtained in situ, in real-time. To extract additional data from these distributed measurements, an experimentally-parameterized equivalent circuit model with a new 'flow capacitor' circuit element was developed to predict the distributions of various system parameters during operation. As a case study, this approach was applied to investigate the behavior of the suspension electrodes used in an electrochemical flow capacitor under flowing and static conditions. The volumetric capacitance is reduced from 15.6 F ml(-1) to 1.1 F ml(-1) under flowing conditions. Results indicate that the majority of the charging in suspension electrodes occurs within ∼750 μm of the current collectors during flow, which gives rise to significant state-of-charge gradients across the cell, as well as underutilization of the available active material. The underlying cause of this observation is attributed to the relatively high electrical resistance of the slurry coupled with a stratified charging regime and insufficient residence time. The observations highlight the need to develop more conductive slurries and to design cells with reduced charge transport lengths.

Time- and Site-Resolved Dynamics in a Topological Circuit

Directory of Open Access Journals (Sweden)

Jia Ningyuan

2015-06-01

Full Text Available From studies of exotic quantum many-body phenomena to applications in spintronics and quantum information processing, topological materials are poised to revolutionize the condensed-matter frontier and the landscape of modern materials science. Accordingly, there is a broad effort to realize topologically nontrivial electronic and photonic materials for fundamental science as well as practical applications. In this work, we demonstrate the first simultaneous site- and time-resolved measurements of a time-reversal-invariant topological band structure, which we realize in a radio-frequency photonic circuit. We control band-structure topology via local permutation of a traveling-wave capacitor-inductor network, increasing robustness by going beyond the tight-binding limit. We observe a gapped density of states consistent with a modified Hofstadter spectrum at a flux per plaquette of ϕ=π/2. In situ probes of the band gaps reveal spatially localized bulk states and delocalized edge states. Time-resolved measurements reveal dynamical separation of localized edge excitations into spin-polarized currents. The radio-frequency circuit paradigm is naturally compatible with nonlocal coupling schemes, allowing us to implement a Möbius strip topology inaccessible in conventional systems. This room-temperature experiment illuminates the origins of topology in band structure, and when combined with circuit quantum electrodynamics techniques, it provides a direct path to topologically ordered quantum matter.

In situ STM imaging of the structures of pentacene molecules adsorbed on Au(111).

Science.gov (United States)

Pong, Ifan; Yau, Shuehlin; Huang, Peng-Yi; Chen, Ming-Chou; Hu, Tarng-Shiang; Yang, Yawchia; Lee, Yuh-Lang

2009-09-01

In situ scanning tunneling microscope (STM) was used to examine the spatial structures of pentacene molecules adsorbed onto a Au(111) single-crystal electrode from a benzene dosing solution containing 16-400 microM pentacene. Molecular-resolution STM imaging conducted in 0.1 M HClO(4) revealed highly ordered pentacene structures of ( radical31 x radical31)R8.9 degrees , (3 x 10), ( radical31 x 10), and ( radical7 x 2 radical7)R19.1 degrees adsorbed on the reconstructed Au(111) electrode dosed with different pentacene solutions. These pentacene structures and the reconstructed Au(111) substrate were stable between 0.2 and 0.8 V [vs reversible hydrogen electrode, RHE]. Increasing the potential to E > 0.8 V lifted the reconstructed Au(111) surface and disrupted the ordered pentacene adlattices simultaneously. Ordered pentacene structures could be restored by applying potentials negative enough to reinforce the reconstructed Au(111). At potentials negative of 0.2 V, the adsorption of protons became increasingly important to displace adsorbed pentacene admolecules. Although the reconstructed Au(111) structure was not essential to produce ordered pentacene adlayers, it seemed to help the adsorption of pentacene molecules in a long-range ordered pattern. At room temperature (25 degrees C), approximately 100 pentacene molecules seen in STM images could rotate and align themselves to a neighboring domain in 10 s, suggesting that pentacene admolecules could be mobile on Au(111) under the STM imaging conditions of -150 mV in bias voltage and 1 nA in feedback current.

In-situ quartz crystal microgravimetric studies of molecular adsorbates containing thiol and hydroquinone moieties bound to Au(111) surfaces in aqueous electrolytes

Energy Technology Data Exchange (ETDEWEB)

Mo, Y.; Sukenik, C.; Sandifer, M. [Case Western Univ., Cleveland, OH (United States); Barriga, R.J.; Soriaga, M.P.; Scherson, D. [Texas A& M Univ., College Station, TX (United States)

1995-12-01

The microgravimetric properties of monolayers of 2, 5-dihydroxythiophenol, 2,5-dihydroxybenzyl mercaptan, and 2, 5-dihydroxy-4-methylbenzyl mercaptan adsorbed on Au(111) single crystal electrodes were examined by in situ quartz crystal microbalance techniques in aqueous perchloric acid electrolytes. The results obtained are consistent with the reversible loss of an average of about three waters per adsorbed molecule as the layers are oxidized and subsequently reduced. These observations provide evidence for discrete changes in the extent of bound water within the hydroquinone/quinone layer as the oxidation state of the monolayer is changed. 9 refs., 4 figs.

Relationship between time-resolved and non-time-resolved Beer-Lambert law in turbid media.

Science.gov (United States)

Nomura, Y; Hazeki, O; Tamura, M

1997-06-01

The time-resolved Beer-Lambert law proposed for oxygen monitoring using pulsed light was extended to the non-time-resolved case in a scattered medium such as living tissues with continuous illumination. The time-resolved Beer-Lambert law was valid for the phantom model and living tissues in the visible and near-infrared regions. The absolute concentration and oxygen saturation of haemoglobin in rat brain and thigh muscle could be determined. The temporal profile of rat brain was reproduced by Monte Carlo simulation. When the temporal profiles of rat brain under different oxygenation states were integrated with time, the absorbance difference was linearly related to changes in the absorption coefficient. When the simulated profiles were integrated, there was a linear relationship within the absorption coefficient which was predicted for fractional inspiratory oxygen concentration from 10 to 100% and, in the case beyond the range of the absorption coefficient, the deviation from linearity was slight. We concluded that an optical pathlength which is independent of changes in the absorption coefficient is a good approximation for near-infrared oxygen monitoring.

Residence time determination for adsorbent beds of different configurations

Energy Technology Data Exchange (ETDEWEB)

Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

1995-02-01

The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

Development of in situ time-resolved Raman spectroscopy facility for dynamic shock loading in materials

Science.gov (United States)

Chaurasia, S.; Rastogi, V.; Rao, U.; Sijoy, C. D.; Mishra, V.; Deo, M. N.

2017-11-01

The transient state of excitation and relaxation processes in materials under shock compression can be investigated by coupling the laser driven shock facility with Raman spectroscopy. For this purpose, a time resolved Raman spectroscopy setup has been developed to monitor the physical and the chemical changes such as phase transitions, chemical reactions, molecular kinetics etc., under shock compression with nanosecond time resolution. This system consist of mainly three parts, a 2 J/8 ns Nd:YAG laser system used for generation of pump and probe beams, a Raman spectrometer with temporal and spectral resolution of 1.2 ns and 3 cm-1 respectively and a target holder in confinement geometry assembly. Detailed simulation for the optimization of confinement geometry targets is performed. Time resolved measurement of polytetrafluoroethylene (PTFE) targets at focused laser intensity of 2.2 GW/cm2 has been done. The corresponding pressure in the Aluminum and PTFE are 3.6 and 1.7 GPa respectively. At 1.7 GPa in PTFE, a red shift of 5 cm-1 is observed for the CF2 twisting mode (291 cm-1). Shock velocity in PTFE is calculated by measuring rate of change of ratios of the intensity of Raman lines scattered from shocked volume to total volume of sample in the laser focal spot along the laser axis. The calculated shock velocity in PTFE is found to be 1.64 ± 0.16 km/s at shock pressure of 1.7 GPa, for present experimental conditions.

Time resolved techniques: An overview

International Nuclear Information System (INIS)

Larson, B.C.; Tischler, J.Z.

1990-06-01

Synchrotron sources provide exceptional opportunities for carrying out time-resolved x-ray diffraction investigations. The high intensity, high angular resolution, and continuously tunable energy spectrum of synchrotron x-ray beams lend themselves directly to carrying out sophisticated time-resolved x-ray scattering measurements on a wide range of materials and phenomena. When these attributes are coupled with the pulsed time-structure of synchrotron sources, entirely new time-resolved scattering possibilities are opened. Synchrotron beams typically consist of sub-nanosecond pulses of x-rays separated in time by a few tens of nanoseconds to a few hundred nanoseconds so that these beams appear as continuous x-ray sources for investigations of phenomena on time scales ranging from hours down to microseconds. Studies requiring time-resolution ranging from microseconds to fractions of a nanosecond can be carried out in a triggering mode by stimulating the phenomena under investigation in coincidence with the x-ray pulses. Time resolution on the picosecond scale can, in principle, be achieved through the use of streak camera techniques in which the time structure of the individual x-ray pulses are viewed as quasi-continuous sources with ∼100--200 picoseconds duration. Techniques for carrying out time-resolved scattering measurements on time scales varying from picoseconds to kiloseconds at present and proposed synchrotron sources are discussed and examples of time-resolved studies are cited. 17 refs., 8 figs

Time-resolved study of formate on Ni( 1 1 1 ) by picosecond SFG spectroscopy

Science.gov (United States)

Kusafuka, K.; Noguchi, H.; Onda, K.; Kubota, J.; Domen, K.; Hirose, C.; Wada, A.

2002-04-01

Time-resolved vibrational measurements were carried out on formate (HCOO) adsorbed on Ni(1 1 1) surface by combining the sum-frequency generation method and picosecond laser system (time resolution of 6 ps). Rapid intensity decrease (within the time resolution) followed by intensity recovery (time constant of several tens of ps) of CH stretching signal was observed when picosecond 800 nm pulse was irradiated on the sample surface. From the results of temperature and pump fluence dependences of temporal behaviour of signal intensity, we concluded that the observed intensity change was induced by non-thermal process. Mechanism of the temporal intensity change was discussed.

Structure-activity relationships of heterogeneous catalysts from time-resolved X-ray absorption spectroscopy

International Nuclear Information System (INIS)

Ressler, T.; Jentoft, R.E.; Wienold, J.; Girgsdies, F.; Neisius, T.; Timpe, O.

2003-01-01

Knowing the composition and the evolution of the bulk structure of a heterogeneous catalyst under working conditions (in situ) is a pre-requisite for understanding structure-activity relationships. X-ray absorption spectroscopy can be employed to study a catalytically active material in situ. In addition to steady-state investigations, the technique permits experiments with a time-resolution in the sub-second range to elucidate the solid-state kinetics of the reactions involved. Combined with mass spectrometry, the evolution of the short-range order structure of a heterogeneous catalyst, the average valence of the constituent metals, and the phase composition can be obtained. Here we present results obtained from time-resolved studies on the reduction of MoO 3 in propene and in propene and oxygen

Time-resolved vibrational spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Tokmakoff, Andrei [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Champion, Paul [Northeastern Univ., Boston, MA (United States); Heilweil, Edwin J. [National Inst. of Standards and Technology (NIST), Boulder, CO (United States); Nelson, Keith A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ziegler, Larry [Boston Univ., MA (United States)

2009-05-14

This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE's Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all fiveof DOE's grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

Detection of rhodopsin dimerization in situ by PIE-FCCS, a time-resolved fluorescence spectroscopy.

Science.gov (United States)

Smith, Adam W

2015-01-01

Rhodopsin self-associates in the plasma membrane. At low concentrations, the interactions are consistent with a monomer-dimer equilibrium (Comar et al., J Am Chem Soc 136(23):8342-8349, 2014). At high concentrations in native tissue, higher-order clusters have been observed (Fotiadis et al., Nature 421:127-128, 2003). The physiological role of rhodopsin dimerization is still being investigated, but it is clear that a quantitative assessment is essential to determining the function of rhodopsin clusters in vision. To quantify rhodopsin interactions, I will outline the theory and methodology of a specialized time-resolved fluorescence spectroscopy for measuring membrane protein-protein interactions called pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). The strength of this technique is its ability to quantify rhodopsin interactions in situ (i.e., a live cell plasma membrane). There are two reasons for restricting the scope to live cell membranes. First, the compositional heterogeneity of the plasma membrane creates a complex milieu with thousands of lipid, protein, and carbohydrate species. This makes it difficult to infer quaternary interactions from detergent solubilized samples or construct a model phospholipid bilayer that recapitulates all of the interactions present in native membranes. Second, organizational structure and dynamics is a key feature of the plasma membrane, and fixation techniques like formaldehyde cross-linking and vitrification will modulate the interactions. PIE-FCCS is based on two-color fluorescence imaging with time-correlated single-photon counting (TCSPC) (Becker et al., Rev Sci Instrum 70:1835-1841, 1999). By time-tagging every detected photon, the data can be analyzed as a fluorescence intensity distribution, fluorescence lifetime histogram, or fluorescence (cross-)correlation spectra (FCS/FCCS) (Becker, Advanced time-correlated single-photon counting techniques, Springer, Berlin, 2005). These

Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kang, Zhitao [Georgia Tech Research Institute, Georgia Institute of Technology, Atlanta, Georgia 30332-0826 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Banishev, Alexandr A.; Christensen, James; Dlott, Dana D. [School of Chemical Sciences and Fredrick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N., E-mail: naresh.thadhani@mse.gatech.edu [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0245 (United States); Xiao, Pan [LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States); Zhou, Min [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405 (United States)

2016-07-28

The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

International Nuclear Information System (INIS)

Kang, Zhitao; Banishev, Alexandr A.; Christensen, James; Dlott, Dana D.; Lee, Gyuhyon; Scripka, David A.; Breidenich, Jennifer; Summers, Christopher J.; Thadhani, Naresh N.; Xiao, Pan; Zhou, Min

2016-01-01

The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

Arsenic removal from water using a novel amorphous adsorbent developed from coal fly ash.

Science.gov (United States)

Zhang, Kaihua; Zhang, Dongxue; Zhang, Kai

2016-01-01

A novel effective adsorbent of alumina/silica oxide hydrate (ASOH) for arsenic removal was developed through simple chemical reactions using coal fly ash. The iron-modified ASOH with enhancing adsorption activity was further developed from raw fly ash based on the in situ technique. The adsorbents were characterized by X-ray diffraction, Fourier transform infrared spectrometry, scanning electron micrograph, laser particle size and Brunauer-Emmet-Teller surface area. The results show that the adsorbents are in amorphous and porous structure, the surface areas of which are 8-12 times that of the raw ash. The acidic hydrothermal treatment acts an important role in the formation of the amorphous structure of ASOH rather than zeolite crystal. A series of adsorption experiments for arsenic on them were studied. ASOH can achieve a high removal efficiency for arsenic of 96.4% from water, which is more than 2.5 times that of the raw ash. Iron-modified ASOH can enhance the removal efficiency to reach 99.8% due to the in situ loading of iron (Fe). The condition of synthesis pH = 2-4 is better for iron-modified ASOH to adsorb arsenic from water.

Application of high-resolution photoelectron spectroscopy: Vibrational resolved C 1s and O 1s spectra of CO adsorbed on Ni(100)

Energy Technology Data Exchange (ETDEWEB)

Foehlisch, A.; Nilsson, A.; Martensson, N. [Uppsala Univ. (Sweden)] [and others

1997-04-01

There are various effects which determine the line shape of a core-level electron spectrum. These are due to the finite life-time of the core hole, inelastic scattering of the outgoing photoelectron, electronic shake-up and shake-off processes and vibrational excitations. For free atoms and molecules the different contributions to the observed line shapes can often be well separated. For solids, surfaces and adsorbates the line shapes are in general much broader and it has in the past been assumed that no separation of the various contributions can be made. In the present report the authors will show that this is indeed not the case. Surprisingly, the vibrational fine structure of CO adsorbed on Ni(100) can be resolved in the C 1s and O 1s electron spectra. This was achieved by the combination of highly monochromatized soft X-rays from B18.0 with a high resolution Scienta 200 mm photoelectron spectrometer. X-ray photoelectron spectroscopy (XPS) with tunable excitation energy yields as a core level spectroscopy atomic and site-specific information. The presented measurements allow for a determination of internuclear distances and potential energy curves in corehole ionized adsorbed molecules. The authors analysis of the c(2x2) phase CO/Ni(100) on {open_quotes}top{close_quotes} yielded a vibrational splitting of 217 +/- 2 meV for C 1s ionization. For O 1s ionization a splitting of 173 +/- 8 meV was found.

Spatially and time-resolved element-specific in situ corrosion investigations with an online hyphenated microcapillary flow injection inductively coupled plasma mass spectrometry set-up

International Nuclear Information System (INIS)

Homazava, N.; Ulrich, A.; Kraehenbuehl, U.

2008-01-01

A novel technique for in situ spatial, time-resolved element-specific investigations of corrosion processes is developed. The technique is based on an online hyphenation of a specially designed microflow-capillary set-up to inductively coupled plasma mass spectrometry (ICP-MS) using flow injection sample introduction. Detailed aspects of the method development, optimization of the sample microflow introduction and flow injection characteristics for the localized corrosion analysis are described. Moreover, specific challenges of the ICP-MS analysis as applied to the analysis of corrosion sample probes, e.g. high matrix load and limited sample volume, are discussed. The efficiency of the developed technique is proved by corrosion susceptibility analysis of a commercial Al alloy. Results of the corrosion experiments of the aluminum alloy AA 6111 are presented to demonstrate the influence of various factors such as exposure time and pH value of the corrosive medium on the element-specific dissolution rates of the alloy. This novel technique provides new aspects in corrosion science and sheds new light on corrosion mechanisms

Real-Time Observation of Platinum Redispersion on Ceria-Based Oxide by In-situ Turbo-XAS in Fluorescence Mode

International Nuclear Information System (INIS)

Nagai, Yasutaka; Dohmae, Kazuhiko; Tanabe, Toshitaka; Shinjoh, Hirofumi; Takagi, Nobuyuki; Ikeda, Yasuo; Guilera, Gemma; Pascarelli, Sakura; Newton, Mark; Matsumoto, Shin'ichi

2007-01-01

A real-time observation of the redispersion behavior of sintered Pt on ceria-based oxide was made possible by in-situ time-resolved Turbo-XAS in fluorescence mode. 2 wt% Pt/Ce-Zr-Y mixed oxide samples were prepared, and then treated under an aging condition. The average Pt particle size measured by CO absorption method after aging was 7 nm. Redispersion treatments of the previously aged catalyst were carried out at 600 deg. C within an in-situ XAS cell in a cyclical flow of reducing/oxidizing gases. Pt L3-edge XANES spectra were collected every 1.1 second under in-situ conditions. From a change in the XANES spectra, we observed that the Pt particle size of the aged catalyst decreased from 7 to 5 nm after 60 seconds and then to 3 nm after 1000 seconds

Ultrafast time-resolved electron diffraction on adsorbate systems on silicon surfaces. Vibrational excitation in monllayers and dynamics of phase transitions; Ultraschnelle zeitaufgeloeste Elektronenbeugung an Adsorbatsystemen auf Siliziumoberflaechen. Vibrationsanregung in Monolagen und Dynamik von Phasenuebergaengen

Energy Technology Data Exchange (ETDEWEB)

Moellenbeck, Simone

2011-04-11

In the present work ultra fast time resolved electron diffraction (TR-RHEED) at various adsorbate systems on silicon (Si) substrates was performed. Using the Debye-Waller-effect, the vibrational amplitude of the excited adsorbate atoms can be directly observed in the experiments as a function of time. For a coverage of 4/3 monolayers Lead (Pb) on Si(1 1 1) forms a ({radical}(3) x {radical}(3))-reconstruction. The transient intensity evolution of the diffraction spots is recorded in a TR-RHEED-experiment. After excitation with a fs-laser pulse the intensity decreases due to the Debye-Waller-effect. The temporal behavior of the de-excitation process can be described with two exponential functions: a short time constant of 100 ps and a long one of 2800 ps. The two time constants can be assigned to two different phonon modes of the Pb-adsorbate. The huge difference between the two time constants and thus difference in the coupling to the substrate is explained by the bonding geometry in the structural model. To confirm this possible explanation, further TR-RHEED-experiments for the ({radical}(7) x {radical}(3))-reconstruction of Pb on Si(1 1 1) were performed. The ({radical}(7) x {radical}(3))-reconstruction with a coverage of 1.2 monolayers shows comparable structural elements. The transient intensity evolution can be described with the identical two time constants. In addition, first experiments on the {beta} ({radical}(3) x {radical}(3))-phase of Pb/Si(1 1 1) are presented. This {beta} ({radical}(3) x {radical}(3))-reconstruction, with a coverage of 1/3 monolayers of Pb, shows a phase transition to a (3 x 3)-reconstruction, which was observed in the experiments. Further investigated adsorbate systems are: ({radical}(3) x {radical}(3))Ag/Si(1 1 1), ({radical}(3) x {radical}(3))In/Si(1 1 1), ({radical}(31) x {radical}(31))In/Si(1 1 1), and ({radical}(3) x {radical}(3))Bi/Si(1 1 1). In the second part of the present work the structural dynamics of strongly driven

Time-resolved absorption measurements on OMEGA

International Nuclear Information System (INIS)

Jaanimagi, P.A.; DaSilva, L.; Delettrez, J.; Gregory, G.G.; Richardson, M.C.

1986-01-01

Time-resolved measurements of the incident laser light that is scattered and/or refracted from targets irradiated by the 24 uv-beam OMEGA laser at LLE, have provided some interesting features related to time-resolved absorption. The decrease in laser absorption characteristic of irradiating a target that implodes during the laser pulse has been observed. The increase in absorption expected as the critical density surface moves from a low to a high Z material in the target has also been noted. The detailed interpretation of these results is made through comparisons with simulation using the code LILAC, as well as with streak data from time-resolved x-ray imaging and spectroscopy. In addition, time and space-resolved imaging of the scattered light yields information on laser irradiation uniformity conditions on the target. The report consists of viewgraphs

In situ evaluation of density, viscosity, and thickness of adsorbed soft layers by combined surface acoustic wave and surface plasmon resonance.

Science.gov (United States)

Francis, Laurent A; Friedt, Jean-Michel; Zhou, Cheng; Bertrand, Patrick

2006-06-15

We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity, and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold-coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is monitored simultaneously in a single setup for the real-time and label-free measurement of the parameters of adsorbed soft layers, which means for layers with a predominant viscous behavior. A general mathematical modeling in equivalent viscoelastic transmission lines is presented to determine the correlation between experimental SAW signal shifts and the waveguide structure including the presence of the adsorbed layer and the supporting liquid from which it segregates. A methodology is presented to identify from SAW and SPR simulations the parameters representatives of the soft layer. During the absorption of a soft layer, thickness or viscosity changes are observed in the experimental ratio of the SAW signal attenuation to the SAW signal phase and are correlated with the theoretical model. As application example, the simulation method is applied to study the thermal behavior of physisorbed PNIPAAm, a polymer whose conformation is sensitive to temperature, under a cycling variation of temperature between 20 and 40 degrees C. Under the assumption of the bulk density and the bulk refractive index of PNIPAAm, thickness and viscosity of the film are obtained from simulations; the viscosity is correlated to the solvent content of the physisorbed layer.

In Situ Evaluation of Density, Viscosity and Thickness of Adsorbed Soft Layers by Combined Surface Acoustic Wave and Surface Plasmon Resonance

OpenAIRE

Francis, L.; Friedt, J. -M.; Zhou, C.; Bertrand, P.

2003-01-01

We show the theoretical and experimental combination of acoustic and optical methods for the in situ quantitative evaluation of the density, the viscosity and the thickness of soft layers adsorbed on chemically tailored metal surfaces. For the highest sensitivity and an operation in liquids, a Love mode surface acoustic wave (SAW) sensor with a hydrophobized gold coated sensing area is the acoustic method, while surface plasmon resonance (SPR) on the same gold surface as the optical method is...

Solvent exchange in a metal–organic framework single crystal monitored by dynamic in situ X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Cox, Jordan M.; Walton, Ian M.; Bateman, Gage; Benson, Cassidy A.; Mitchell, Travis; Sylvester, Eric; Chen, Yu-Sheng; Benedict, Jason B. (UC); (Buffalo)

2017-07-25

Understanding the processes by which porous solid-state materials adsorb and release guest molecules would represent a significant step towards developing rational design principles for functional porous materials. To elucidate the process of liquid exchange in these materials, dynamicin situX-ray diffraction techniques have been developed which utilize liquid-phase chemical stimuli. Using these time-resolved diffraction techniques, the ethanol solvation process in a flexible metal–organic framework [Co(AIP)(bpy)_0.5(H₂O)]·2H₂O was examined. The measurements provide important insight into the nature of the chemical transformation in this system including the presence of a previously unreported neat ethanol solvate structure.

Time-resolved ESR spectroscopy

International Nuclear Information System (INIS)

Beckert, D.

1986-06-01

The time-resolved ESR spectroscopy is one of the modern methods in radiospectroscopy and plays an important role in solving various problems in chemistry and biology. Proceeding from the basic ideas of time-resolved ESR spectroscopy the experimental equipment is described generally including the equipment developed at the Central Institute of Isotope and Radiation Research. The experimental methods applied to the investigation of effects of chemically induced magnetic polarization of electrons and to kinetic studies of free radicals in polymer systems are presented. The theory of radical pair mechanism is discussed and theoretical expressions are summarized in a computer code to compute the theoretical polarization for each pair of the radicals

Effects of quartz particle size and water-to-solid ratio on hydrothermal synthesis of tobermorite studied by in-situ time-resolved X-ray diffraction

International Nuclear Information System (INIS)

Kikuma, J.; Tsunashima, M.; Ishikawa, T.; Matsuno, S.; Ogawa, A.; Matsui, K.; Sato, M.

2011-01-01

Hydrothermal synthesis process of tobermorite (5CaO.6SiO 2 .5H 2 O) has been investigated by in-situ X-ray diffraction using high-energy X-rays from a synchrotron radiation source in combination with a purpose-build autoclave cell. Dissolution rates of quartz were largely affected by its particle size distribution in the starting mixtures. However, the composition (Ca/Si) of non-crystalline C-S-H at the start of tobermorite formation was identical regardless of the quartz dissolution rate. An effect of water-to-solid ratio (w/s) was investigated for samples using fine particle quartz. Tobermorite did not occur with w/s of 1.7 but occurred with w/s higher than 3.0. Surprisingly, however, the dissolution curves of quartz were nearly identical for all samples with w/s from 1.7 to 9, indicating that the dissolution rate is predominated by surface area. Possible reaction mechanism for tobermorite formation will be discussed in terms of Ca and/or silicate ion concentration in the liquid phase and distribution of Ca/Si in non-crystalline C-S-H. - Graphical abstract: Time-resolved XRD data set was obtained at up to 190 deg. C under a saturated steam pressure. Tobermorite (5CaO.6SiO 2 .5H 2 O) formation reaction was investigated in detail for several different starting materials. Highlights: → Hydrothermal formation of tobermorite was monitored by in-situ XRD. → Ca/Si of C-S-H at the start time of tobermorite formation was determined. → The Ca/Si value was identical regardless of the quartz particle size in the starting mixture.

Thin film growth studies using time-resolved x-ray scattering

Science.gov (United States)

Kowarik, Stefan

2017-02-01

Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

In situ, rapid, and temporally resolved measurements of cellulase adsorption onto lignocellulosic substrates by UV-vis spectrophotometry

Science.gov (United States)

Hao Liu; J. Y. Zhu; X. S. Chai

2011-01-01

This study demonstrated two in situ UV-vis spectrophotometric methods for rapid and temporally resolved measurements of cellulase adsorption onto cellulosic and lignocellulosic substrates during enzymatic hydrolysis. The cellulase protein absorption peak at 280 nm was used for quantification. The spectral interferences from light scattering by small fibers (fines) and...

Time-resolved photoelectron spectrometry of a dephasing process in pyrazine

International Nuclear Information System (INIS)

Pavlov, R.L.; Pavlov, L.I.; Delchev, Ya.I.; Pavlova, S.I.

2001-01-01

The first femtosecond time-resolved photoelectron imaging (PEI) is presented. The method is characterized by photoionization of NO and further applied to ultrafast dephasing in pyrazine. Intermediate case behaviour in radiationless transition is clearly observed in time-resolved photoelectron kinetic energy distribution. Femtosecond PEI is with much improved efficiency than conventional photoelectron spectroscopies. It is anticipated that the unifield approach of time-resolved photoelectron and photoion imaging opens the possibility of observing photon-induced dynamics in real time

In situ co-precipitation preparation of a superparamagnetic graphene oxide/Fe3O4 nanocomposite as an adsorbent for wastewater purification: synthesis, characterization, kinetics, and isotherm studies.

Science.gov (United States)

Pu, Shengyan; Xue, Shengyang; Yang, Zeng; Hou, Yaqi; Zhu, Rongxin; Chu, Wei

2018-04-13

A superparamagnetic graphene oxide (GO)/Fe 3 O 4 nanocomposite (MGO) was prepared by a facile in situ co-precipitation strategy, resulting in a prospective material for the application of graphene oxide in wastewater treatment. MGO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The prepared adsorbent showed a high adsorption efficiency relevant to the purification of dye-contaminated wastewater and could be readily magnetically separated. The maximum adsorption capacity was ca. 546.45 mg g -1 for the common cationic dye methylene blue (MB) and ca. 628.93 mg g -1 for the anionic dye Congo red (CR). The adsorption processes fit the pseudo-second-order kinetic model well, which revealed that these processes may involve the chemical interaction between adsorbate and adsorbent. The thermodynamic parameters indicated that the adsorption reaction was an endothermic and spontaneous process. Furthermore, the prepared magnetic adsorbent had a wide effective pH range from 5 to 11 and showed good stability after five reuse cycles. The synthetic MGO showed great potential as a promising adsorbent for organic contaminant removal in wastewater treatment.

Improvements in brain activation detection using time-resolved diffuse optical means

Science.gov (United States)

Montcel, Bruno; Chabrier, Renee; Poulet, Patrick

2005-08-01

An experimental method based on time-resolved absorbance difference is described. The absorbance difference is calculated over each temporal step of the optical signal with the time-resolved Beer-Lambert law. Finite element simulations show that each step corresponds to a different scanned zone and that cerebral contribution increases with the arrival time of photons. Experiments are conducted at 690 and 830 nm with a time-resolved system consisting of picosecond laser diodes, micro-channel plate photo-multiplier tube and photon counting modules. The hemodynamic response to a short finger tapping stimulus is measured over the motor cortex. Time-resolved absorbance difference maps show that variations in the optical signals are not localized in superficial regions of the head, which testify for their cerebral origin. Furthermore improvements in the detection of cerebral activation is achieved through the increase of variations in absorbance by a factor of almost 5 for time-resolved measurements as compared to non-time-resolved measurements.

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium.

Science.gov (United States)

Hu, Baiyang; Fugetsu, Bunshi; Yu, Hongwen; Abe, Yoshiteru

2012-05-30

We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent. Copyright © 2012 Elsevier B.V. All rights reserved.

Seventh international conference on time-resolved vibrational spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Dyer, R.B.; Martinez, M.A.D.; Shreve, A.; Woodruff, W.H. [comps.

1997-04-01

The International Conference on Time-Resolved Vibrational Spectroscopy (TRVS) is widely recognized as the major international forum for the discussion of advances in this rapidly growing field. The 1995 conference was the seventh in a series that began at Lake Placid, New York, 1982. Santa Fe, New Mexico, was the site of the Seventh International Conference on Time-Resolved Vibrational Spectroscopy, held from June 11 to 16, 1995. TRVS-7 was attended by 157 participants from 16 countries and 85 institutions, and research ranging across the full breadth of the field of time-resolved vibrational spectroscopy was presented. Advances in both experimental capabilities for time-resolved vibrational measurements and in theoretical descriptions of time-resolved vibrational methods continue to occur, and several sessions of the conference were devoted to discussion of these advances and the associated new directions in TRVS. Continuing the interdisciplinary tradition of the TRVS meetings, applications of time-resolved vibrational methods to problems in physics, biology, materials science, and chemistry comprised a large portion of the papers presented at the conference.

Time-resolved CT angiography in aortic dissection

International Nuclear Information System (INIS)

Meinel, Felix G.; Nikolaou, Konstantin; Weidenhagen, Rolf; Hellbach, Katharina; Helck, Andreas; Bamberg, Fabian; Reiser, Maximilian F.; Sommer, Wieland H.

2012-01-01

Objectives: We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection. Materials and methods: 14 consecutive patients with known or suspected aortic dissection (aged 60 ± 9 years) referred for aortic CT angiography were scanned on a dual-source CT scanner (Somatom Definition Flash; Siemens, Forchheim, Germany) using a shuttle mode for multiphasic image acquisition (range 48 cm, time resolution 6 s, 6 phases, 100 kV, 110 mAs/rot). Effective radiation doses were calculated from recorded dose length products. For all phases, CT densities were measured in the aortic lumen and renal parenchyma. From the multiphasic data, 3 phases corresponding to a triphasic standard CT protocol, served as a reference and were compared against findings from the time-resolved datasets. Results: Mean effective radiation dose was 27.7 ± 3.5 mSv. CT density of the true lumen peaked at 355 ± 53 HU. Compared to the simulated triphasic protocol, time-resolved CT angiography added diagnostic information regarding a number of important findings: the enhancement delay between true and false lumen (n = 14); the degree of membrane oscillation (n = 14); the perfusion delay in arteries originating from the false lumen (n = 9). Other additional information included true lumen collapse (n = 4), quantitative assessment of renal perfusion asymmetry (n = 2), and dynamic occlusion of aortic branches (n = 2). In 3/14 patients (21%), these additional findings of the multiphasic protocol altered patient management. Conclusions: Multiphasic, time-resolved CT angiography covering the entire aorta is feasible at a reasonable effective radiation dose and adds significant diagnostic information with therapeutic consequences in patients with aortic dissection.

In Situ Planetary Mineralogy Using Simultaneous Time Resolved Fluorescence and Raman Spectroscopy

Science.gov (United States)

Blacksberg, J.; Rossman , G.R.

2011-01-01

Micro-Raman spectroscopy is one of the primary methods of mineralogical analysis in the laboratory, and more recently in the field. Because of its versatility and ability to interrogate rocks in their natural form it is one of the front runners for the next generation of in situ instruments designed to explore adverse set of solar system bodies (e.g. Mars, Venus, the Moon, and other primitive bodies such as asteroids and the Martian moons Phobos and Deimos), as well as for pre-selection of rock and soil samples for potential cache and return missions.

Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

Science.gov (United States)

Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

2010-01-14

The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

Numerical simulations of time-resolved quantum electronics

International Nuclear Information System (INIS)

Gaury, Benoit; Weston, Joseph; Santin, Matthieu; Houzet, Manuel; Groth, Christoph; Waintal, Xavier

2014-01-01

Numerical simulation has become a major tool in quantum electronics both for fundamental and applied purposes. While for a long time those simulations focused on stationary properties (e.g. DC currents), the recent experimental trend toward GHz frequencies and beyond has triggered a new interest for handling time-dependent perturbations. As the experimental frequencies get higher, it becomes possible to conceive experiments which are both time-resolved and fast enough to probe the internal quantum dynamics of the system. This paper discusses the technical aspects–mathematical and numerical–associated with the numerical simulations of such a setup in the time domain (i.e. beyond the single-frequency AC limit). After a short review of the state of the art, we develop a theoretical framework for the calculation of time-resolved observables in a general multiterminal system subject to an arbitrary time-dependent perturbation (oscillating electrostatic gates, voltage pulses, time-varying magnetic fields, etc.) The approach is mathematically equivalent to (i) the time-dependent scattering formalism, (ii) the time-resolved non-equilibrium Green’s function (NEGF) formalism and (iii) the partition-free approach. The central object of our theory is a wave function that obeys a simple Schrödinger equation with an additional source term that accounts for the electrons injected from the electrodes. The time-resolved observables (current, density, etc.) and the (inelastic) scattering matrix are simply expressed in terms of this wave function. We use our approach to develop a numerical technique for simulating time-resolved quantum transport. We find that the use of this wave function is advantageous for numerical simulations resulting in a speed up of many orders of magnitude with respect to the direct integration of NEGF equations. Our technique allows one to simulate realistic situations beyond simple models, a subject that was until now beyond the simulation

Time-resolved infrared absorption study of nine TiO2 photocatalysts

International Nuclear Information System (INIS)

Yamakata, Akira; Ishibashi, Taka-aki; Onishi, Hiroshi

2007-01-01

Electron kinetics of nine TiO 2 catalysts were compared in a microsecond time domain. Each catalyst was band-gap excited with an UV light pulse, and electron-induced absorption of mid infrared light was observed as a function of time delay. The probability of electron-hole recombination in the bulk, electron attachment to adsorbed oxygen, and hole attachment to adsorbed methoxy species was estimated

Time-resolved quantitative phosphoproteomics

DEFF Research Database (Denmark)

Verano-Braga, Thiago; Schwämmle, Veit; Sylvester, Marc

2012-01-01

proteins involved in the Ang-(1-7) signaling, we performed a mass spectrometry-based time-resolved quantitative phosphoproteome study of human aortic endothelial cells (HAEC) treated with Ang-(1-7). We identified 1288 unique phosphosites on 699 different proteins with 99% certainty of correct peptide...

Time-resolved SFG study of formate on a Ni( 1 1 1 ) surface under irradiation of picosecond laser pulses

Science.gov (United States)

Noguchi, H.; Okada, T.; Onda, K.; Kano, S. S.; Wada, A.; Domen, K.

2003-03-01

Time-resolved sum-frequency generation spectroscopy was carried out on a deuterated formate (DCOO) adsorbed on Ni(1 1 1) surface to investigate the surface reaction dynamics under instantaneous surface temperature jump induced by the irradiation by picosecond laser pulses. The irradiation of pump pulse (800 nm) caused the rapid intensity decrease of both CD and OCO stretching modes of bridged formate on Ni(1 1 1). Different temporal behaviors of intensity recovery between these two vibrational modes were observed, i.e., CD stretching mode recovered faster than OCO. This is the first result to show that the dynamics of adsorbates on metals strongly depends on the observed vibrational mode. From the results of temperature and pump fluence dependence, we concluded that the observed intensity change was not due to the decomposition or desorption, but was induced by a non-thermal process.

Time-resolved studies. Ch. 9

International Nuclear Information System (INIS)

Mills, Dennis M.; Argonne National Lab., IL

1991-01-01

Synchrotron radiation, with its unique properties, offers a tool to extend X-ray measurements from the static to the time-resolved regime. The most straight-forward application of synchrotron radiation to the study of transient phenomena is directly through the possibility of decreased data-collection times via the enormous increase in flux over that of a laboratory X-ray system. Even further increases in intensity can be obtained through the use of novel X-ray optical devices. Wide-bandpass monochromators, e.g., that utilize the continuous spectral distribution of synchrotron radiation, can increase flux on the sample several orders of magnitude over conventional X-ray optical systems thereby allowing a further shortening of the data-collection time. Another approach that uses the continuous spectral nature of synchrotron radiation to decrease data-collection times is the 'parallel data collection' method. Using this technique, intensities as a function of X-ray energy are recorded simultaneously for all energies rather than sequentially recording data at each energy, allowing for a dramatic decrease in data-collection time. Perhaps the most exciting advances in time-resolved X-ray studies will be made by those methods that exploit the pulsed nature of the radiation emitted from storage rings. Pulsed techniques have had an enormous impact in the study of the temporal evolution of transient phenomena. The extension from continuous to modulated sources for use in time-resolved work has been carried over in a host of fields that use both pulsed particle and pulsed electro-magnetic beams. In this chapter the new experimental techniques are reviewed and illustrated with some experiments. (author). 98 refs.; 20 figs.; 5 tabs

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

Energy Technology Data Exchange (ETDEWEB)

Hu, Baiyang [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Fugetsu, Bunshi, E-mail: hu@ees.hokudai.ac.jp [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Yu, Hongwen [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Abe, Yoshiteru [Kyoei Engineering Corporation, Niigata 959-1961 (Japan)

2012-05-30

Highlights: Black-Right-Pointing-Pointer Prussian blue was sealed in cavities of diatomite using carbon nanotubes. Black-Right-Pointing-Pointer The caged Prussian blue after being permanently immobilized in polyurethane spongy showed a 167 mg/g capability for absorbing cesium. Black-Right-Pointing-Pointer Cesium elimination was accomplished by simply adding the Prussian-blue based spongiform adsorbent to radioactive water. - Abstract: We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent.

Time-resolved chromatographic analysis and mechanisms in adsorption and catalysis.

Science.gov (United States)

Roubani-Kalantzopoulou, Fani

2009-03-06

The main object of this review is the study of fundamentals of adsorption and heterogeneous catalysis, a benefit for the understanding of adsorptive and catalytic properties. This work aims to define and record, with the utmost accuracy, the phenomena and the possible reactions. A new methodology for the study of the adsorption is presented, which is a version of the well-known inverse gas chromatography. This reversed-flow inverse gas chromatography (RF-IGC) is technically very simple, and it is combined with a mathematical analysis that gives the possibility for the estimation of various physicochemical parameters related to adsorbent or catalyst characterization, under conditions compatible with the operation of real adsorbents and catalysts. On this base, this methodology has been successfully applied to the study of the impact of air pollutants, volatile organic and/or inorganic, on many solids such as marbles, ceramics, oxide-pigments of works of art, building materials, authentic statues of the Greek Archaeological Museums. Moreover, this methodology proved to be a powerful tool for studying the topography of active sites of heterogeneous surfaces in the nano-scale domain. Thus, some very important local quantities for the surface chemistry have been determined experimentally for many solids including thin films. These physicochemical local quantities (among which adsorption energy and entropy, surface diffusion coefficient, probability density function) have been determined from the experimental pairs of height of extra chromatographic peaks and time by a nonlinear least-squares method, through personal computer programs written in GW BASIC and lately in FORTRAN. Through the time-resolved analysis the surface characterization of the examined materials took place. In addition, the kinetic constants responsible for adsorption/desorption and surface chemical reactions have also been calculated. Thus, important answers have been provided to the following

Time-resolved x-ray diffraction analysis of the experimental dehydration of serpentine at high pressure

International Nuclear Information System (INIS)

Inoue, Toru; Yoshimi, Isamu; Yamada, Akihiro; Kikegawa, Takumi

2009-01-01

Time-resolved, in situ X-ray diffraction analysis was used to determine the dehydration rate and kinetics of serpentine during experimental dehydration at high pressures. The capsule used comprises a diamond sleeve fitted with Au or Pt lids in order to provide high-quality, time-resolved X-ray diffraction data. Antigorite quickly dehydrated to enstatite + forsterite + fluid within 2 h at 650degC below ∼6 GPa. Avrami modeling of the results and SEM observations of the partially dehydrated sample revealed that the nucleation rate was quite high for enstatite but low for forsterite, showing incubation periods of ∼10 min before appearing. The crystallization of these minerals is controlled largely by the composition of the fluid generated from serpentine dehydration. The dehydration boundary determined below 6 GPa in the present study is consistent with the results of previous phase equilibrium studies. This study indicates that serpentine in a subducting slab dehydrates rapidly below 6 GPa when the slab intersects the dehydration boundary conditions. (author)

Deflection evaluation using time-resolved radiography

International Nuclear Information System (INIS)

Fry, D.A.; Lucero, J.P.

1990-01-01

Time-resolved radiography is the creation of an x-ray image for which both the start-exposure and stop-exposure times are known with respect to the event under study. The combination of image and timing are used to derive information about the event. The authors have applied time-resolved radiography to evaluate motions of explosive-driven events. In the particular application discussed in this paper, the author's intent is to measure maximum deflections of the components involved. Exposures are made during the time just before to just after the event of interest occurs. A smear or blur of motion out to its furthest extent is recorded on the image. Comparison of the dynamic images with static images allows deflection measurements to be made

[A new measurement method of time-resolved spectrum].

Science.gov (United States)

Shi, Zhi-gang; Huang, Shi-hua; Liang, Chun-jun; Lei, Quan-sheng

2007-02-01

A new method for measuring time-resolved spectrum (TRS) is brought forward. Programming with assemble language controlled the micro-control-processor (AT89C51), and a kind of peripheral circuit constituted the drive circuit, which drived the stepping motor to run the monochromator. So the light of different kinds of expected wavelength could be obtained. The optical signal was transformed to electrical signal by optical-to-electrical transform with the help of photomultiplier tube (Hamamatsu 1P28). The electrical signal of spectrum data was transmitted to the oscillograph. Connecting the two serial interfaces of RS232 between the oscillograph and computer, the electrical signal of spectrum data could be transmitted to computer for programming to draw the attenuation curve and time-resolved spectrum (TRS) of the swatch. The method for measuring time-resolved spectrum (TRS) features parallel measurement in time scale but serial measurement in wavelength scale. Time-resolved spectrum (TRS) and integrated emission spectrum of Tb3+ in swatch Tb(o-BBA)3 phen were measured using this method. Compared with the real time-resolved spectrum (TRS). It was validated to be feasible, credible and convenient. The 3D spectra of fluorescence intensity-wavelength-time, and the integrated spectrum of the swatch Tb(o-BBA)3 phen are given.

In situ polyphenyl derivatisation and the effect of thermal decomposition of adsorbed and chemisorbed polyphenyls on the structure of multi-wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Gergely, Andras, E-mail: doohan11@chemres.hu [Department of Surface Modification and Nanostructures, Institute of Nanochemistry and Catalysis, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary); Ujszaszy, Kalman [Mass Spectrometry Department, Institute of Structural Chemistry, Pusztaszeri ut 59-67, Chemical Research Center of the Hungarian Academy of Sciences, Budapest 1025 (Hungary); Peltz, Csaba [EGIS Pharmaceuticals PLC, Kereszturi ut 30-38, Budapest 1106 (Hungary); Kiraly, Peter; Tarkanyi, Gabor [NMR Spectroscopy Department, Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary); Mihaly, Judith [Department of Biological Nanochemistry, Institute of Nanochemistry and Catalysis, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary); Kalman, Erika [Department of Surface Modification and Nanostructures, Institute of Nanochemistry and Catalysis, Chemical Research Center of the Hungarian Academy of Sciences, Pusztaszeri ut 59-67, Budapest 1025 (Hungary)

2011-05-01

This study presents the exploitation of an alternative reaction route of deamination of arylamines to perform in situ derivatisation of multi-walled carbon nanotubes (MWCNTs) with polyphenyl (PPh) species of various masses. As a result of consecutive derivatisation, high conversion of PPh grafting of the MWCNTs was realised with the collateral outgrowth of physical modification with adsorbed additional PPhs. Applied derivatisation process exceeds the monolayer coverage related superficial saturation limitations in the overall grafting yield of the nanotubes. Thus, a linear relationship was recognized between the overall quantities of chemisorbed PPhs composed of D{sub 5}-phenylene oligomers and the applied excess of diazonium activated reagents, corresponding to {sup 2}H MAS NMR spectroscopy results. According to mass spectrometry (MS) investigations, uniform thermal decomposition of the chemisorbed PPhs modified MWCNTs was found besides the more intense and altered decomposition characteristic-featured adsorbate-chemisorbate PPhs contained MWCNTs during sequential pyrolysis under inert atmosphere. This is attributed to the pyrolysis provoked isomerisation, decomposition and the formation of adsorbed and chemisorbed PPh moieties. As a result, a mediated and an even more pronounced degradation in the order of graphitic lattice of the MWCNTs were evidenced in the adsorbate-chemisorbate and the chemisorbate PPhs contained samples by FT-Raman spectroscopy and transmission electron microscopy (TEM), respectively. {sup 2}H MAS NMR supplied results of relevant amount of deuterium in the chemisorbate PPh contained sample without traces of aromatic related MS detected volatile products, these allow us to conclude about a thermally stable derivatisation that is interpreted as an endohedral modification of the nanotubes.

Carbon/Attapulgite Composites as Recycled Palm Oil-Decoloring and Dye Adsorbents

Directory of Open Access Journals (Sweden)

Guangyan Tian

2018-01-01

Full Text Available Activated clay minerals have been widely used in the edible oil refining industry for decolorization of crude oil by adsorption, and so far many methods have been used to improve their decolorization efficiency. Herein, we successfully prepared a series of carbon/attapulgite (C/APT composite adsorbents by a one-step in-situ carbonization process with natural starch (St as the carbon source. It has been revealed that the adsorbent had better decolorization efficiency for crude palm oil than acid-activated APT. However, more than a million tons of decolorized waste is produced every year in the oil-refining industry, which was often treated as solid waste and has not yet been reutilized effectively. In order to explore a viable method to recycle and reuse the decolorant, the waste decolorant was further prepared into new C/APT adsorbents for the removal of dyes from wastewater, and then the dyes adsorbed on the adsorbent were used as the carbon sources to produce new C/APT adsorbents by a cyclic carbonization process. The results showed that the adsorbents prepared from the decolorized waste could remove more than 99.5% of the methylene blue (MB, methyl violet (MV, and malachite green (MG dyes from the simulated wastewater with the dye concentration of 200 mg/L, and the C/APT–Re adsorbent consecutively regenerated five times using the adsorbed dyes as a carbon source still exhibit good adsorption efficiency for dyes. As a whole, this process opens a new avenue to develop efficient decolorants of palm oil and achieves recyclable utilization of decolored waste.

Resolving intramolecular-distortion changes induced by the partial fluorination of pentacene adsorbed on Cu(111)

Science.gov (United States)

Franco-Cañellas, Antoni; Wang, Qi; Broch, Katharina; Shen, Bin; Gerlach, Alexander; Bettinger, Holger F.; Duhm, Steffen; Schreiber, Frank

2018-04-01

We experimentally quantify the molecular bending of a partially fluorinated pentacene (PEN) compound, namely 2,3,9,10-tetrafluoropentacene (F4PEN), adsorbed on Cu(111). By means of the x-ray standing wave (XSW) technique, we directly measure the adsorption distance of three inequivalent carbon sites, the fluorine atoms as well as the total and backbone carbon average adsorption distances. The precise positioning of different sites within the carbon core allows us to resolve two adsorption behaviors, namely a PEN-like strong coupling between the backbone and the substrate, and a repulsive interaction involving the fluorinated short molecular edges, which are 0.91 ±0.09 Å above the central benzene ring. This finding is further supported by additional electronic and in-plane-structure measurements, thus showing that the selective fluorination of a PEN molecule has only a local conformational effect and it is not sufficient to modify its interface properties. Yet, in the multilayer regime, the electronic and growth properties of the film differ completely from those of PEN and its perfluorinated derivative.

An x-ray detector for time-resolved studies

International Nuclear Information System (INIS)

Rodricks, B.; Brizard, C.; Clarke, R.; Lowe, W.

1992-01-01

The development of ultrahigh-brightness x-ray sources makes time-resolved x-ray studies more and more feasible. Improvements in x-ray optics components are also critical for obtaining the appropriate beam for a particular type of experiment. Moreover, fast parallel detectors will be essential in order to exploit the combination of high intensity x-ray sources and novel optics for time-resolved experiments. A CCD detector with a time resolution of microseconds has been developed at the Advanced Photon Source (APS). This detector is fully programmable using CAMAC electronics and a Micro Vax computer. The techniques of time-resolved x-ray studies, which include scattering, microradiography, microtomography, stroboscopy, etc., can be applied to a range of phenomena (including rapid thermal annealing, surface ordering, crystallization, and the kinetics of phase transition) in order to understand these time-dependent microscopic processes. Some of these applications will be illustrated by recent results performed at synchrotrons. New powerful x-ray sources now under construction offer the opportunity to apply innovative approaches in time-resolved work

Characterization for solidification and phase transformations of pure-titanium steel weld metal with time-resolved X-ray diffraction system

International Nuclear Information System (INIS)

Terasaki, Hidenori; Komizo, Yu-ichi; Nishino, Fumihiro; Ikeda, Masahiko

2007-01-01

Understanding and controlling solidification and phase transformation process of weld metal is essential for forming the microstructure with superior mechanical property. Recent evolution of analysis technique makes for solidification and phase transformation process to be in-situ analyzed, in direct and reciprocal lattice space. In the present work, unidirectional-solidification and phase transformation in the weld metal of commercial pure-titanium in Gas Tungsten Arc welding was in-situ observed by using Time-Resolved X-Ray Diffraction system with two-dimensional pixel detector. An undulator beam was used as a probe. Larger diffraction area could be detected in the time-resolution of 0.05 seconds, in unidirectional solidification and subsequent phase transformation process of pure-titanium weld metal. Furthermore, the microstructure formation during β-α phase transformation was in situ observed with High temperature Laser Scanning Confocal Microscopy. The crystal configurations in unidirectional solidification of weld metal and rapid change of phase ratio in reconstructive phase transformation were clearly analyzed. (author)

Time-resolved emission from laser-ablated uranium

International Nuclear Information System (INIS)

Stoffels, E.; Mullen, J. van der; Weijer, P. van de

1991-01-01

Time-resolved emission spectra from the plasma, induced by laser ablation of uranium samples have been studied. The dependence of the emission intensity on time is strongly affected by the nature and pressure of the buffer gas. Air and argon have been used in the pressure range 0.002 to 5 mbar. The emission intensity as a function of time displays three maxima, indicating that three different processes within the expanding plasma plume are involved. On basis of the time-resolved spectra we propose a model that explains qualitatively the phenomena that are responsible for this time behaviour. (author)

Heat transfer between adsorbate and laser-heated hot electrons

International Nuclear Information System (INIS)

Ueba, H; Persson, B N J

2008-01-01

Strong short laser pulses can give rise to a strong increase in the electronic temperature at metal surfaces. Energy transfer from the hot electrons to adsorbed molecules may result in adsorbate reactions, e.g. desorption or diffusion. We point out the limitations of an often used equation to describe the heat transfer process in terms of a friction coupling. We propose a simple theory for the energy transfer between the adsorbate and hot electrons using a newly introduced heat transfer coefficient, which depends on the adsorbate temperature. We calculate the transient adsorbate temperature and the reaction yield for a Morse potential as a function of the laser fluency. The results are compared to those obtained using a conventional heat transfer equation with temperature-independent friction. It is found that our equation of energy (heat) transfer gives a significantly lower adsorbate peak temperature, which results in a large modification of the reaction yield. We also consider the heat transfer between different vibrational modes excited by hot electrons. This mode coupling provides indirect heating of the vibrational temperature in addition to the direct heating by hot electrons. The formula of heat transfer through linear mode-mode coupling of two harmonic oscillators is applied to the recent time-resolved study of carbon monoxide and atomic oxygen hopping on an ultrafast laser-heated Pt(111) surface. It is found that the maximum temperature of the frustrated translation mode can reach high temperatures for hopping, even when direct friction coupling to the hot electrons is not strong enough

Time-resolved infrared absorption study of nine TiO{sub 2} photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Yamakata, Akira; Ishibashi, Taka-aki [Kanagawa Academy of Science and Technology (KAST), KSP, Takatsu, Kawasaki 213-0012 (Japan); Onishi, Hiroshi [Kanagawa Academy of Science and Technology (KAST), KSP, Takatsu, Kawasaki 213-0012 (Japan)], E-mail: oni@kobe-u.ac.jp

2007-10-15

Electron kinetics of nine TiO{sub 2} catalysts were compared in a microsecond time domain. Each catalyst was band-gap excited with an UV light pulse, and electron-induced absorption of mid infrared light was observed as a function of time delay. The probability of electron-hole recombination in the bulk, electron attachment to adsorbed oxygen, and hole attachment to adsorbed methoxy species was estimated.

Time-resolved investigations of the non-thermal ablation process of graphite induced by femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Kalupka, C., E-mail: christian.kalupka@llt.rwth-aachen.de; Finger, J. [Chair for Laser Technology LLT, RWTH Aachen University, Aachen 52074 (Germany); Reininghaus, M. [Chair for Laser Technology LLT, RWTH Aachen University, Aachen 52074 (Germany); Fraunhofer Institute for Laser Technology ILT, Steinbachstraße 15, Aachen 52074 (Germany)

2016-04-21

We report on the in-situ analysis of the ablation dynamics of the, so-called, laser induced non-thermal ablation process of graphite. A highly oriented pyrolytic graphite is excited by femtosecond laser pulses with fluences below the classic thermal ablation threshold. The ablation dynamics are investigated by axial pump-probe reflection measurements, transversal pump-probe shadowgraphy, and time-resolved transversal emission photography. The combination of the applied analysis methods allows for a continuous and detailed time-resolved observation of the non-thermal ablation dynamics from several picoseconds up to 180 ns. Formation of large, μm-sized particles takes place within the first 3.5 ns after irradiation. The following propagation of ablation products and the shock wave front are tracked by transversal shadowgraphy up to 16 ns. The comparison of ablation dynamics of different fluences by emission photography reveals thermal ablation products even for non-thermal fluences.

In situ adsorption of bovine submaxillary mucin at the mica/aqueous solution interface

International Nuclear Information System (INIS)

Perez, E.; Proust, J.E.; Baszkin, A.; Boissonnade, M.M.

1984-01-01

An in situ adsorption measurement method at the mica/protein solution interface is described. An apparatus especially constructed for this purpose permits direct and continuous measurement of total adsorption (reversible and irreversible) of 14 C-labelled proteins. Bovine submaxillary mucin (BSM), extracted from salivary glands, was acetylated with (CH 3 14 CO) 2 O. The results show the increase of BSM adsorbed on mica surfaces with its concentration in solution and adsorption time. Pseudo plateaux are obtained for all concentrations studied, indicating the formation of thick layers. The loosely bound fraction of adsorbed mucin is proportional to the bulk concentration in solution. The amount of BSM adsorbed increases in the neighbourhood of the isoelectric point of BSM (pH 3). (Auth.)

Structure–acidity correlation of supported tungsten(VI)-oxo-species: FT-IR and TPD studies of adsorbed pyridine and catalytic decomposition of 2-propanol

Energy Technology Data Exchange (ETDEWEB)

Zaki, M.I., E-mail: mizaki@mu.edu.eg; Mekhemer, G.A.H.; Fouad, N.E.; Rabee, A.I.M.

2014-07-01

The amount of 10 wt%-WO{sub 3} was supported on alumina, titania or silica by impregnation with aqueous solution of ammonium paratungstate and subsequent calcination at 500 °C for 10 h. Tungstate-related chemical and physical changes in the calcination products were resolved by ex-situ infrared (IR) spectroscopy. Nature of exposed surface acid sites were probed by in-situ IR spectroscopy of adsorbed pyridine (Py) molecules at room temperature (RT). The relative strength of the acid sites thus probed was gauged by combining results of temperature-programmed desorption (TPD) measurements of the RT-adsorbed Py with those communicated by in-situ IR spectra of residual Py on the surface after a brief thermoevacuation at high temperatures (100–300 °C). Reactivity of the surface acid sites was tested toward 2-propanal catalytic decomposition, and observed by in-situ IR gas phase spectra. Results obtained were correlated with predominant structures assumed by the supported tungstate species. Accordingly, polymerization of the supported tungstate into 2-/3-dimensional structures, was found to be relatively most advanced on favorable locations of titania surfaces as compared to the case on alumina or silica surfaces. Consequently, the Lewis acidity was strengthened, and strong Bronsted acidity was evolved, leading to a 2-propanol dehydration catalyst (tungstate/titania) of optimal activity and selectivity. Strong tungstate/support interfacial interactions were found to hamper the formation of the strongly acidic and catalytically active polymeric structures of the supported tungstate (i.e., the case on alumina or silica).

Structure–acidity correlation of supported tungsten(VI)-oxo-species: FT-IR and TPD studies of adsorbed pyridine and catalytic decomposition of 2-propanol

International Nuclear Information System (INIS)

Zaki, M.I.; Mekhemer, G.A.H.; Fouad, N.E.; Rabee, A.I.M.

2014-01-01

The amount of 10 wt%-WO 3 was supported on alumina, titania or silica by impregnation with aqueous solution of ammonium paratungstate and subsequent calcination at 500 °C for 10 h. Tungstate-related chemical and physical changes in the calcination products were resolved by ex-situ infrared (IR) spectroscopy. Nature of exposed surface acid sites were probed by in-situ IR spectroscopy of adsorbed pyridine (Py) molecules at room temperature (RT). The relative strength of the acid sites thus probed was gauged by combining results of temperature-programmed desorption (TPD) measurements of the RT-adsorbed Py with those communicated by in-situ IR spectra of residual Py on the surface after a brief thermoevacuation at high temperatures (100–300 °C). Reactivity of the surface acid sites was tested toward 2-propanal catalytic decomposition, and observed by in-situ IR gas phase spectra. Results obtained were correlated with predominant structures assumed by the supported tungstate species. Accordingly, polymerization of the supported tungstate into 2-/3-dimensional structures, was found to be relatively most advanced on favorable locations of titania surfaces as compared to the case on alumina or silica surfaces. Consequently, the Lewis acidity was strengthened, and strong Bronsted acidity was evolved, leading to a 2-propanol dehydration catalyst (tungstate/titania) of optimal activity and selectivity. Strong tungstate/support interfacial interactions were found to hamper the formation of the strongly acidic and catalytically active polymeric structures of the supported tungstate (i.e., the case on alumina or silica).

Programming for time resolved spectrum in pulse radiolysis experiments

International Nuclear Information System (INIS)

Betty, C.A.; Panajkar, M.S.; Shirke, N.D.

1993-01-01

A user friendly program in Pascal has been developed for data acquisition and subsequent processing of time resolved spectra of transient species produced in pulse radiolysis experiments. The salient features of the program are (i) thiocyanate dosimetry and (ii) spectrum acquisition. The thiocyanate dosimetry is carried out to normalize experimental conditions to a standard value as determined by computing absorbance of the transient signal CNS -2 that is produced from thiocyanate solution by a 7 MeV electron pulse. Spectrum acquisition allows the acquisition of the time resolved data at 20 different times points and subsequent display of the plots of absorbance vs. wavelength for the desired time points during the experiment. It is also possible to plot single time point spectrum as well as superimposed spectra for different time points. Printing, editing and merging facilities are also provided. (author). 2 refs., 7 figs

Introduction to Time-Resolved Spectroscopy: Nanosecond Transient Absorption and Time-Resolved Fluorescence of Eosin B

Science.gov (United States)

Farr, Erik P.; Quintana, Jason C.; Reynoso, Vanessa; Ruberry, Josiah D.; Shin, Wook R.; Swartz, Kevin R.

2018-01-01

Here we present a new undergraduate laboratory that will introduce the concepts of time-resolved spectroscopy and provide insight into the natural time scales on which chemical dynamics occur through direct measurement. A quantitative treatment of the acquired data will provide a deeper understanding of the role of quantum mechanics and various…

Emerging biomedical applications of time-resolved fluorescence spectroscopy

Science.gov (United States)

Lakowicz, Joseph R.; Szmacinski, Henryk; Koen, Peter A.

1994-07-01

Time-resolved fluorescence spectroscopy is presently regarded as a research tool in biochemistry, biophysics, and chemical physics. Advances in laser technology, the development of long-wavelength probes, and the use of lifetime-based methods are resulting in the rapid migration of time-resolved fluorescence to the clinical chemistry lab, to the patient's bedside, to flow cytometers, to the doctor's office, and even to home health care. Additionally, time-resolved imaging is now a reality in fluorescence microscopy, and will provide chemical imaging of a variety of intracellular analytes and/or cellular phenomena. In this overview paper we attempt to describe some of the opportunities available using chemical sensing based on fluorescence lifetimes, and to predict those applications of lifetime-based sensing which are most likely in the near future.

Time-resolved resonance Raman spectroscopy of radiation-chemical processes

International Nuclear Information System (INIS)

Tripathi, G.N.R.

1983-01-01

A tunable pulsed laser Raman spectrometer for time resolved Raman studies of radiation-chemical processes is described. This apparatus utilizes the state of art optical multichannel detection and analysis techniques for data acquisition and electron pulse radiolysis for initiating the reactions. By using this technique the resonance Raman spectra of intermediates with absorption spectra in the 248-900 nm region, and mean lifetimes > 30 ns can be examined. This apparatus can be used to time resolve the vibrational spectral overlap between transients absorbing in the same region, and to follow their decay kinetics by monitoring the well resolved Raman peaks. For kinetic measurements at millisecond time scale, the Raman technique is preferable over optical absorption method where low frequency noise is quite bothersome. A time resolved Raman study of the pulse radiolytic oxidation of aqueous tetrafluorohydroquinone and p-methoxyphenol is briefly discussed. 15 references, 5 figures

Electronic properties of adsorbates and clean surfaces of metals and semiconductors

International Nuclear Information System (INIS)

Lecante, J.

1980-01-01

This paper surveys recent progress in experimental studies on electronic properties of adsorbates and clean metal surfaces. Electron spectroscopy and particularly angle resolved photoelectron spectroscopy appears to be a very powerful tool to get informations on electronic levels of adsorbates or clean surfaces. Moreover this technique may also give informations about the atomic geometry of the surface. Experimental investigation about surface plasmons, surface states, core level shifts are presented for clean surfaces. As examples of adsorbate covered surfaces two typical cases are chosen: two dimensional band structure and oriented molecules. Finally the photoelectron diffraction may be used for surface structure determination either in the case of an adsorbate or a clean metal surface [fr

In-pile Thermal Conductivity Characterization with Time Resolved Raman

Energy Technology Data Exchange (ETDEWEB)

Wang, Xinwei [Iowa State Univ., Ames, IA (United States). Dept. of Mechanical Engineering; Hurley, David H. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2018-03-19

The project is designed to achieve three objectives: (1) Develop a novel time resolved Raman technology for direct measurement of fuel and cladding thermal conductivity. (2) Validate and improve the technology development by measuring ceramic materials germane to the nuclear industry. (3) Conduct instrumentation development to integrate optical fiber into our sensing system for eventual in-pile measurement. We have developed three new techniques: time-domain differential Raman (TD-Raman), frequency-resolved Raman (FR-Raman), and energy transport state-resolved Raman (ET-Raman). The TD-Raman varies the laser heating time and does simultaneous Raman thermal probing, the FR-Raman probes the material’s thermal response under periodical laser heating of different frequencies, and the ET-Raman probes the thermal response under steady and pulsed laser heating. The measurement capacity of these techniques have been fully assessed and verified by measuring micro/nanoscale materials. All these techniques do not need the data of laser absorption and absolute material temperature rise, yet still be able to measure the thermal conductivity and thermal diffusivity with unprecedented accuracy. It is expected they will have broad applications for in-pile thermal characterization of nuclear materials based on pure optical heating and sensing.

Advanced hydraulic fracturing methods to create in situ reactive barriers

International Nuclear Information System (INIS)

Murdoch, L.

1997-01-01

This article describes the use of hydraulic fracturing to increase permeability in geologic formations where in-situ remedial action of contaminant plumes will be performed. Several in-situ treatment strategies are discussed including the use of hydraulic fracturing to create in situ redox zones for treatment of organics and inorganics. Hydraulic fracturing methods offer a mechanism for the in-situ treatment of gently dipping layers of reactive compounds. Specialized methods using real-time monitoring and a high-energy jet during fracturing allow the form of the fracture to be influenced, such as creation of assymmetric fractures beneath potential sources (i.e. tanks, pits, buildings) that should not be penetrated by boring. Some examples of field applications of this technique such as creating fractures filled with zero-valent iron to reductively dechlorinate halogenated hydrocarbons, and the use of granular activated carbon to adsorb compounds are discussed

Resolving Key Uncertainties in Subsurface Energy Recovery: One Role of In Situ Experimentation and URLs (Invited)

Science.gov (United States)

Elsworth, D.

2013-12-01

Significant uncertainties remain and influence the recovery of energy from the subsurface. These uncertainties include the fate and transport of long-lived radioactive wastes that result from the generation of nuclear power and have been the focus of an active network of international underground research laboratories dating back at least 35 years. However, other nascent carbon-free energy technologies including conventional and EGS geothermal methods, carbon-neutral methods such as carbon capture and sequestration and the utilization of reduced-carbon resources such as unconventional gas reservoirs offer significant challenges in their effective deployment. We illustrate the important role that in situ experiments may play in resolving behaviors at extended length- and time-scales for issues related to chemical-mechanical interactions. Significantly, these include the evolution of transport and mechanical characteristics of stress-sensitive fractured media and their influence of the long-term behavior of the system. Importantly, these interests typically relate to either creating reservoirs (hydroshearing in EGS reservoirs, artificial fractures in shales and coals) or maintaining seals at depth where the permeating fluids may include mixed brines, CO2, methane and other hydrocarbons. Critical questions relate to the interaction of these various fluid mixtures and compositions with the fractured substrate. Important needs are in understanding the roles of key processes (transmission, dissolution, precipitation, sorption and dynamic stressing) on the modification of effective stresses and their influence on the evolution of permeability, strength and induced seismicity on the resulting development of either wanted or unwanted fluid pathways. In situ experimentation has already contributed to addressing some crucial issues of these complex interactions at field scale. Important contributions are noted in understanding the fate and transport of long-lived wastes

Portable double-sided pulsed laser heating system for time-resolved geoscience and materials science applications.

Science.gov (United States)

Aprilis, G; Strohm, C; Kupenko, I; Linhardt, S; Laskin, A; Vasiukov, D M; Cerantola, V; Koemets, E G; McCammon, C; Kurnosov, A; Chumakov, A I; Rüffer, R; Dubrovinskaia, N; Dubrovinsky, L

2017-08-01

A portable double-sided pulsed laser heating system for diamond anvil cells has been developed that is able to stably produce laser pulses as short as a few microseconds with repetition frequencies up to 100 kHz. In situ temperature determination is possible by collecting and fitting the thermal radiation spectrum for a specific wavelength range (particularly, between 650 nm and 850 nm) to the Planck radiation function. Surface temperature information can also be time-resolved by using a gated detector that is synchronized with the laser pulse modulation and space-resolved with the implementation of a multi-point thermal radiation collection technique. The system can be easily coupled with equipment at synchrotron facilities, particularly for nuclear resonance spectroscopy experiments. Examples of applications include investigations of high-pressure high-temperature behavior of iron oxides, both in house and at the European Synchrotron Radiation Facility using the synchrotron Mössbauer source and nuclear inelastic scattering.

Time-resolved Femtosecond Photon Echo Probes Bimodal Solvent Dynamics

NARCIS (Netherlands)

Pshenichnikov, M.S; Duppen, K.; Wiersma, D. A.

1995-01-01

We report on time-resolved femtosecond photon echo experiments of a dye molecule in a polar solution. The photon echo is time resolved by mixing the echo with a femtosecond gate pulse in a nonlinear crystal. It is shown that the temporal profile of the photon echo allows separation of the

In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

Energy Technology Data Exchange (ETDEWEB)

Li, Dan, E-mail: dany@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Jia, Shaojie [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Fodjo, Essy Kouadio [Laboratory of Physical Chemistry, University Felix Houphouet Boigny, 22 BP 582, Abidjan 22, Cote d’Ivoire (Cote d' Ivoire); Xu, Hu [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Wang, Yuhong, E-mail: yuhong_wang502@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Deng, Wei [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China)

2016-03-30

Graphical abstract: The orientation of anthraquinone-2-carboxylic acid (AQ-2-COOH) has been investigated by in situ surface-enhanced Raman scattering (in situ SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) on silver surface. - Highlights: • The adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on Ag electrode is influenced by the pH. • The pH-dependant adsorption of AQ-2-COOH has been confirmed by in situ surface-enhanced Raman scattering (in situ SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS). • The results can provide insights into electron transfer reactions of AQ-2-COOH in biological systems. - Abstract: In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from −0.3 to −0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from −0.3 to −0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

The state of physically adsorbed substances in microporous adsorbents

International Nuclear Information System (INIS)

Fomkin, A.A.

1987-01-01

Xe, Kr, Ar, CF 3 Cl, CH 4 adsorption in NaX microporous zeolite of 0.98 Na 2 OxAl 2 O 3 x2.36SiO 2 x0.02H 2 O is studied. Some properties of adsorbates (density, coefficients of expansion, enthalpy, heat capacity) are determined and discussed. The adsorbate in the microporous adsorbent is shown to be a particular state of a substance. Liniarity of adsorption isosteres and sharp changes during isosteric heat capacity of the adsorbate points to the fact that in microporous adsorbents phase transformations of the second type are possible

Removal of phosphate from eutrophic lakes through adsorption by in situ formation of magnesium hydroxide from diatomite.

Science.gov (United States)

Xie, Fazhi; Wu, Fengchang; Liu, Guijian; Mu, Yunsong; Feng, Chenglian; Wang, Huanhua; Giesy, John P

2014-01-01

Since in situ formation of Mg(OH)2 can efficiently sorb phosphate (PO4) from low concentrations in the environment, a novel dispersed magnesium oxide nanoflake-modified diatomite adsorbent (MOD) was developed for use in restoration of eutrophic lakes by removal of excess PO4. Various adsorption conditions, such as pH, temperature and contact time were investigated. Overall, sorption capacities increased with increasing temperature and contact time, and decreased with increasing pH. Adsorption of PO4 was well described by both the Langmuir isotherm and pseudo second-order models. Theoretical maximum sorption capacity of MOD for PO4 was 44.44-52.08 mg/g at experimental conditions. Characterization of PO4 adsorbed to MOD by use of X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and solid state (31)P nuclear magnetic resonance revealed that electrostatic attraction, surface complexation and chemical conversion in situ were the major forces in adsorption of PO4. Mg(OH)2 formed in situ had a net positive charge on the surface of the MOD that could adsorb PO4(3-) and HPO4(2-) anion to form surface complex and gradually convert to Mg3(PO4)2 and MgHPO4. Efficiency of removal of PO4 was 90% when 300 mg MOD/L was added to eutrophic lake water. Results presented here demonstrated the potential use of the MOD for restoration of eutrophic lakes by removal of excess PO4.

Radiation-induced polymerization monitored in situ by time-resolved fluorescence of probe molecules in methyl methacrylate

International Nuclear Information System (INIS)

Frahn, Mark S.; Abellon, Ruben D.; Luthjens, Leonard H.; Vermeulen, Martien J.W.; Warman, John M.

2003-01-01

A technique is presented for monitoring radiation-induced polymerizations in situ based on the measurement of the fluorescence lifetime of molecular probes dissolved in the polymerizing medium. This method is illustrated with results on methyl methacrylate (MMA) using two fluorogenic probe molecules; N-(2-anthracene)methacrylamide (AnMA) and maleimido-fluoroprobe (MFP), a molecule which has a highly dipolar excited state

Time-resolved terahertz spectroscopy of semiconductor nanostructures

DEFF Research Database (Denmark)

Porte, Henrik

This thesis describes time-resolved terahertz spectroscopy measurements on various semiconductor nanostructures. The aim is to study the carrier dynamics in these nanostructures on a picosecond timescale. In a typical experiment carriers are excited with a visible or near-infrared pulse and by me......This thesis describes time-resolved terahertz spectroscopy measurements on various semiconductor nanostructures. The aim is to study the carrier dynamics in these nanostructures on a picosecond timescale. In a typical experiment carriers are excited with a visible or near-infrared pulse...... and by measuring the transmission of a terahertz probe pulse, the photoconductivity of the excited sample can be obtained. By changing the relative arrival time at the sample between the pump and the probe pulse, the photoconductivity dynamics can be studied on a picosecond timescale. The rst studied semiconductor...

Femtosecond Time-resolved Optical Polarigraphy (FTOP)

International Nuclear Information System (INIS)

Aoshima, S.; Fujimoto, M.; Hosoda, M.; Tsuchiya, Y.

2000-01-01

A novel time-resolved imaging technique named FTOP (Femtosecond Time-resolved Optical Polarigraphy) for visualizing the ultrafast propagation dynamics of intense light pulses in a medium has been proposed and demonstrated. Femtosecond snapshot images can be created with a high spatial resolution by imaging only the polarization components of the probe pulse; these polarization components change due to the instantaneous birefringence induced by the pump pulse in the medium. Ultrafast temporal changes in the two-dimensional spatial distribution of the optical pulse intensity were clearly visualized in consecutive images by changing the delay between the pump and probe. We observe that several filaments appear and then come together before the vacuum focus due to nonlinear effects in air. We also prove that filamentation dynamics such as the formation position and the propagation behavior are complex and are strongly affected by the pump energy. The results collected clearly show that this method FTOP succeeds for the first time in directly visualizing the ultrafast dynamics of the self-modulated nonlinear propagation of light. (author)

Photoemission spectroscopy of surfaces and adsorbates

International Nuclear Information System (INIS)

Chiang, T.C.; Kaindl, G.; Himpsel, F.J.; Eastman, D.E.

1982-01-01

Core level photoelectron spectroscopy is providing new information concerning the electronic properties of adsorbates and surfaces. Several examples will be discussed, including studies of adsorbed rare gas submonolayers and multilayers as well as clean metal surfaces. For rare gas multilayers adsorbed on metal surfaces, the photoelectrons and Auger electrons exhibit well-resolved increases in kinetic energy with decreasing distance between the excited atom and the substrate, allowing a direct labeling of the layers. These energy shifts are mainly due to the substrate screening effects, and can be described well by an image-charge model. For a Kr/Xe bilayer system prepared by first coating a Pd substrate with a monolayer of Kr and then overcoating with a layer of Xe, a thermally activated layer inversion process is observed when the temperature is raised, with Xe coming in direct contact with the substrate. For rare gas submonolayers adsorbed on the Al(111) surface, coverage-dependent core level shift and work function measurements provide information about the adatom spatial distributions, polarizabilities, and dipole moments for the ground and excited states. We have also studied the 2p core level shifts for a clean Al(001) surface relative to the bulk. The shifts have a large contribution from the initial-state effects

In situ and real-time small-angle neutron scattering studies of living anionic polymerization process and polymerization-induced self-assembly of block copolymers

International Nuclear Information System (INIS)

Tanaka, H.; Yamauchi, K.; Hasegawa, H.; Miyamoto, N.; Koizumi, S.; Hashimoto, T.

2006-01-01

We have studied a simultaneous living anionic polymerization process of isoprene and deuterated styrene in deuterated benzene with sec-buthyl lithium as an initiator into polyisoprene-block-poly(styrene-d 8 ) and the polymerization-induced self-assembling process. This polymerization-induced self-assembling process was directly observed by an in situ and real-time small-angle neutron scattering (SANS) experiment. The time-resolved SANS studies enabled us to explore a time evolution of hierarchical structures induced by a time evolution of the primary structure (linear sequential connection of two monomers)

Enhanced vanillin production from ferulic acid using adsorbent resin.

Science.gov (United States)

Hua, Dongliang; Ma, Cuiqing; Song, Lifu; Lin, Shan; Zhang, Zhaobin; Deng, Zixin; Xu, Ping

2007-03-01

High vanillin productivity was achieved in the batch biotransformation of ferulic acid by Streptomyces sp. strain V-1. Due to the toxicity of vanillin and the product inhibition, fed-batch biotransformation with high concentration of ferulic acid was unsuccessful. To solve this problem and improve the vanillin yield, a biotransformation strategy using adsorbent resin was investigated. Several macroporous adsorbent resins were chosen to adsorb vanillin in situ during the bioconversion. Resin DM11 was found to be the best, which adsorbed the most vanillin and the least ferulic acid. When 8% resin DM11 (wet w/v) was added to the biotransformation system, 45 g l(-1) ferulic acid could be added continually and 19.2 g l(-1) vanillin was obtained within 55 h, which was the highest vanillin yield by bioconversion until now. This yield was remarkable for exceeding the crystallization concentration of vanillin and therefore had far-reaching consequence in its downstream processing.

In vitro hydroxyapatite adsorbed salivary proteins

International Nuclear Information System (INIS)

Vitorino, Rui; Lobo, Maria Joao C.; Duarte, Jose; Ferrer-Correia, Antonio J.; Tomer, Kenneth B.; Dubin, Joshua R.; Domingues, Pedro M.; Amado, Francisco M.L.

2004-01-01

In spite of the present knowledge about saliva components and their respective functions, the mechanism(s) of pellicle and dental plaque formation have hitherto remained obscure. This has prompted recent efforts on in vitro studies using hydroxyapatite (HA) as an enamel model. In the present study salivary proteins adsorbed to HA were extracted with TFA and EDTA and resolved by 2D electrophoresis over a pH range between 3 and 10, digested, and then analysed by MALDI-TOF/TOF mass spectrometry and tandem mass spectrometry. Nineteen different proteins were identified using automated MS and MS/MS data acquisition. Among them, cystatins, amylase, carbonic anhydrase, and calgranulin B, were identified

Time-Resolved In Situ Liquid-Phase Atomic Force Microscopy and Infrared Nanospectroscopy during the Formation of Metal-Organic Framework Thin Films.

Science.gov (United States)

Mandemaker, Laurens D B; Filez, Matthias; Delen, Guusje; Tan, Huanshu; Zhang, Xuehua; Lohse, Detlef; Weckhuysen, Bert M

2018-04-19

Metal-organic framework (MOF) thin films show unmatched promise as smart membranes and photocatalytic coatings. However, their nucleation and growth resulting from intricate molecular assembly processes are not well understood yet are crucial to control the thin film properties. Here, we directly observe the nucleation and growth behavior of HKUST-1 thin films by real-time in situ AFM at different temperatures in a Cu-BTC solution. In combination with ex situ infrared (nano)spectroscopy, synthesis at 25 °C reveals initial nucleation of rapidly growing HKUST-1 islands surrounded by a continuously nucleating but slowly growing HKUST-1 carpet. Monitoring at 13 and 50 °C shows the strong impact of temperature on thin film formation, resulting in (partial) nucleation and growth inhibition. The nucleation and growth mechanisms as well as their kinetics provide insights to aid in future rational design of MOF thin films.

Time-Resolved In Situ Liquid-Phase Atomic Force Microscopy and Infrared Nanospectroscopy during the Formation of Metal–Organic Framework Thin Films

Science.gov (United States)

2018-01-01

Metal–organic framework (MOF) thin films show unmatched promise as smart membranes and photocatalytic coatings. However, their nucleation and growth resulting from intricate molecular assembly processes are not well understood yet are crucial to control the thin film properties. Here, we directly observe the nucleation and growth behavior of HKUST-1 thin films by real-time in situ AFM at different temperatures in a Cu-BTC solution. In combination with ex situ infrared (nano)spectroscopy, synthesis at 25 °C reveals initial nucleation of rapidly growing HKUST-1 islands surrounded by a continuously nucleating but slowly growing HKUST-1 carpet. Monitoring at 13 and 50 °C shows the strong impact of temperature on thin film formation, resulting in (partial) nucleation and growth inhibition. The nucleation and growth mechanisms as well as their kinetics provide insights to aid in future rational design of MOF thin films. PMID:29595980

Time-resolved fluorescence spectroscopy

International Nuclear Information System (INIS)

Gustavsson, Thomas; Mialocq, Jean-Claude

2007-01-01

This article addresses the evolution in time of light emitted by a molecular system after a brief photo-excitation. The authors first describe fluorescence from a photo-physical point of view and discuss the characterization of the excited state. Then, they explain some basic notions related to fluorescence characterization (lifetime and decays, quantum efficiency, so on). They present the different experimental methods and techniques currently used to study time-resolved fluorescence. They discuss basic notions of time resolution and spectral reconstruction. They briefly present some conventional methods: intensified Ccd cameras, photo-multipliers and photodiodes associated with a fast oscilloscope, and phase modulation. Other methods and techniques are more precisely presented: time-correlated single photon counting (principle, examples, and fluorescence lifetime imagery), streak camera (principle, examples), and optical methods like the Kerr optical effect (principle and examples) and fluorescence up-conversion (principle and theoretical considerations, examples of application)

Time-resolved wave profile measurements in copper to Megabar pressures

Energy Technology Data Exchange (ETDEWEB)

Chhabildas, L C; Asay, J R

1981-01-01

Many time-resolved techniques have been developed which have greatly aided in the understanding of dynamic material behavior such as the high pressure-dynamic strength of materials. In the paper, time-resolved measurements of copper (at shock-induced high pressures and temperatures) are used to illustrate the capability of using such techniques to investigate high pressure strength. Continuous shock loading and release wave profiles have been made in copper to 93 GPa using velocity interferometric techniques. Fine structure in the release wave profiles from the shocked state indicates an increase in shear strength of copper to 1.5 GPa at 93 GPa from its ambient value of 0.08 GPa.

Advances in high-order harmonic generation sources for time-resolved investigations

Energy Technology Data Exchange (ETDEWEB)

Reduzzi, Maurizio [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Carpeggiani, Paolo [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Kühn, Sergei [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Calegari, Francesca [Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Nisoli, Mauro; Stagira, Salvatore [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Vozzi, Caterina [Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Dombi, Peter [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Wigner Research Center for Physics, 1121 Budapest (Hungary); Kahaly, Subhendu [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Tzallas, Paris; Charalambidis, Dimitris [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Foundation for Research and Technology – Hellas, Institute of Electronic Structure and Lasers, P.O. Box 1527, GR-711 10 Heraklion, Crete (Greece); Varju, Katalin [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Department of Optics and Quantum Electronics, University of Szeged, Dóm tér 9, 6720 Szeged (Hungary); Osvay, Karoly [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); and others

2015-10-15

We review the main research directions ongoing in the development of extreme ultraviolet sources based on high-harmonic generation for the synthesization and application of trains and isolated attosecond pulses to time-resolved spectroscopy. A few experimental and theoretical works will be discussed in connection to well-established attosecond techniques. In this context, we present the unique possibilities offered for time-resolved investigations on the attosecond timescale by the new Extreme Light Infrastructure Attosecond Light Pulse Source, which is currently under construction.

Advances in high-order harmonic generation sources for time-resolved investigations

International Nuclear Information System (INIS)

Reduzzi, Maurizio; Carpeggiani, Paolo; Kühn, Sergei; Calegari, Francesca; Nisoli, Mauro; Stagira, Salvatore; Vozzi, Caterina; Dombi, Peter; Kahaly, Subhendu; Tzallas, Paris; Charalambidis, Dimitris; Varju, Katalin; Osvay, Karoly

2015-01-01

We review the main research directions ongoing in the development of extreme ultraviolet sources based on high-harmonic generation for the synthesization and application of trains and isolated attosecond pulses to time-resolved spectroscopy. A few experimental and theoretical works will be discussed in connection to well-established attosecond techniques. In this context, we present the unique possibilities offered for time-resolved investigations on the attosecond timescale by the new Extreme Light Infrastructure Attosecond Light Pulse Source, which is currently under construction.

The analysis of time-resolved optically stimulated luminescence: I. Theoretical considerations

International Nuclear Information System (INIS)

Chithambo, M L

2007-01-01

This is the first of two linked papers on the analysis of time-resolved optically stimulated luminescence. This paper focusses on a theoretical basis of analytical methods and on methods for interpretation of time-resolved luminescence spectra and calculation of luminescence throughput. Using a comparative analysis of the principal features of time-resolved luminescence and relevant analogues from steady state optical stimulation, formulae for configuring a measurement system for optimum performance are presented. We also examine the possible use of stretched-exponential functions for analysis of time-resolved optically stimulated luminescence spectra

Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

Energy Technology Data Exchange (ETDEWEB)

Lambert, P. K.; Hustedt, C. J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C. [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Vecchio, K. S. [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States); Huskins, E. L. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37830 (United States); US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005 (United States); Casem, D. T. [US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005 (United States); Gruner, S. M. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853 (United States); Tate, M. W.; Philipp, H. T.; Purohit, P.; Weiss, J. T. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Woll, A. R. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Kannan, V.; Ramesh, K. T. [Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kenesei, P.; Okasinski, J. S.; Almer, J. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2014-09-15

We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼10{sup 3}–10{sup 4} s{sup −1} in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation.

A time-resolved image sensor for tubeless streak cameras

Science.gov (United States)

Yasutomi, Keita; Han, SangMan; Seo, Min-Woong; Takasawa, Taishi; Kagawa, Keiichiro; Kawahito, Shoji

2014-03-01

This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .

Finite-difference time-domain analysis of time-resolved terahertz spectroscopy experiments

DEFF Research Database (Denmark)

Larsen, Casper; Cooke, David G.; Jepsen, Peter Uhd

2011-01-01

In this paper we report on the numerical analysis of a time-resolved terahertz (THz) spectroscopy experiment using a modified finite-difference time-domain method. Using this method, we show that ultrafast carrier dynamics can be extracted with a time resolution smaller than the duration of the T...

Time-resolved materials science opportunities using synchrotron x-ray sources

International Nuclear Information System (INIS)

Larson, B.C.; Tischler, J.Z.

1995-06-01

The high brightness, high intensity, and pulsed time-structure of synchrotron sources provide new opportunities for time-resolved x-ray diffraction investigations. With third generation synchrotron sources coming on line, high brilliance and high brightness are now available in x-ray beams with the highest flux. In addition to the high average flux, the instantaneous flux available in synchrotron beams is greatly enhanced by the pulsed time structure, which consists of short bursts of x-rays that are separated by ∼tens to hundreds of nanoseconds. Time-resolved one- and two-dimensional position sensitive detection techniques that take advantage of synchrotron radiation for materials science x-ray diffraction investigations are presented, and time resolved materials science applications are discussed in terms of recent diffraction and spectroscopy results and materials research opportunities

Alignment of time-resolved data from high throughput experiments.

Science.gov (United States)

Abidi, Nada; Franke, Raimo; Findeisen, Peter; Klawonn, Frank

2016-12-01

To better understand the dynamics of the underlying processes in cells, it is necessary to take measurements over a time course. Modern high-throughput technologies are often used for this purpose to measure the behavior of cell products like metabolites, peptides, proteins, [Formula: see text]RNA or mRNA at different points in time. Compared to classical time series, the number of time points is usually very limited and the measurements are taken at irregular time intervals. The main reasons for this are the costs of the experiments and the fact that the dynamic behavior usually shows a strong reaction and fast changes shortly after a stimulus and then slowly converges to a certain stable state. Another reason might simply be missing values. It is common to repeat the experiments and to have replicates in order to carry out a more reliable analysis. The ideal assumptions that the initial stimulus really started exactly at the same time for all replicates and that the replicates are perfectly synchronized are seldom satisfied. Therefore, there is a need to first adjust or align the time-resolved data before further analysis is carried out. Dynamic time warping (DTW) is considered as one of the common alignment techniques for time series data with equidistant time points. In this paper, we modified the DTW algorithm so that it can align sequences with measurements at different, non-equidistant time points with large gaps in between. This type of data is usually known as time-resolved data characterized by irregular time intervals between measurements as well as non-identical time points for different replicates. This new algorithm can be easily used to align time-resolved data from high-throughput experiments and to come across existing problems such as time scarcity and existing noise in the measurements. We propose a modified method of DTW to adapt requirements imposed by time-resolved data by use of monotone cubic interpolation splines. Our presented approach

Time-resolved studies

International Nuclear Information System (INIS)

Mills, D.M.

1992-01-01

When new or more powerful probes become available that offer both shorter data-collection times and the opportunity to apply innovative approaches to established techniques, it is natural that investigators consider the feasibility of exploring the kinetics of time-evolving systems. This stimulating area of research not only can lead to insights into the metastable or excited states that a system may populate on its way to a ground state, but can also lead to a better understanding of that final state. Synchrotron radiation, with its unique properties, offers just such a tool to extend X-ray measurements from the static to the time-resolved regime. The most straight-forward application of synchrotron radiation to the study of transient phenomena is directly through the possibility of decreased data-collection times via the enormous increase in flux over that of a laboratory X-ray system. Even further increases in intensity can be obtained through the use of novel X-ray optical devices. Widebandpass monochromators, e.g., that utilize the continuous spectral distribution of synchrotron radiation, can increase flux on the sample several orders of magnitude over conventional X-ray optical systems thereby allowing a further shortening of the data-collection time. Another approach that uses the continuous spectral nature of synchrotron radiation to decrease data-collection times is the open-quote parallel data collectionclose quotes method. Using this technique, intensities as a function of X-ray energy are recorded simultaneously for all energies rather than sequentially recording data at each energy, allowing for a dramatic decrease in the data-collection time

Time-resolved single-shot terahertz time-domain spectroscopy for ultrafast irreversible processes

Science.gov (United States)

Zhai, Zhao-Hui; Zhong, Sen-Cheng; Li, Jun; Zhu, Li-Guo; Meng, Kun; Li, Jiang; Liu, Qiao; Peng, Qi-Xian; Li, Ze-Ren; Zhao, Jian-Heng

2016-09-01

Pulsed terahertz spectroscopy is suitable for spectroscopic diagnostics of ultrafast events. However, the study of irreversible or single shot ultrafast events requires ability to record transient properties at multiple time delays, i.e., time resolved at single shot level, which is not available currently. Here by angular multiplexing use of femtosecond laser pulses, we developed and demonstrated a time resolved, transient terahertz time domain spectroscopy technique, where burst mode THz pulses were generated and then detected in a single shot measurement manner. The burst mode THz pulses contain 2 sub-THz pulses, and the time gap between them is adjustable up to 1 ns with picosecond accuracy, thus it can be used to probe the single shot event at two different time delays. The system can detect the sub-THz pulses at 0.1 THz-2.5 THz range with signal to noise ratio (SNR) of ˜400 and spectrum resolution of 0.05 THz. System design was described here, and optimizations of single shot measurement of THz pulses were discussed in detail. Methods to improve SNR were also discussed in detail. A system application was demonstrated where pulsed THz signals at different time delays of the ultrafast process were successfully acquired within single shot measurement. This time resolved transient terahertz time domain spectroscopy technique provides a new diagnostic tool for irreversible or single shot ultrafast events where dynamic information can be extracted at terahertz range within one-shot experiment.

Time-resolved spectroscopy defines perturbation in molecules

International Nuclear Information System (INIS)

Ahmed, K.

1998-01-01

Time-resolved LIF spectroscopy is employed in order to investigate perturbations in different excited electronic state of alkali molecules. Dunham Coefficients are used to search the selected excited ro-vibrational level, which is overlap with the other nearby excited states. Lifetime measurement has been performed of more than 50 ro-vibrational levels. Out of these 25 levels were observed drastically different lifetimes from the other unperturbed levels. In this report, influence of different perturbations on this anomalous behavior is investigated and discussed. (author)

Alginate Adsorbent Immobilization Technique Promotes Biobutanol Production by Clostridium acetobutylicum Under Extreme Condition of High Concentration of Organic Solvent

Directory of Open Access Journals (Sweden)

Zhuoliang Ye

2018-05-01

Full Text Available In Acetone-Butanol-Ethanol fermentation, bacteria should tolerate high concentrations of solvent products, which inhibit bacteria growth and limit further increase of solvents to more than 20 g/L. Moreover, this limited solvent concentration significantly increases the cost of solvent separation through traditional approaches. In this study, alginate adsorbent immobilization technique was successfully developed to assist in situ extraction using octanol which is effective in extracting butanol but presents strong toxic effect to bacteria. The adsorbent improved solvent tolerance of Clostridium acetobutylicum under extreme condition of high concentration of organic solvent. Using the developed technique, more than 42% of added bacteria can be adsorbed to the adsorbent. Surface area of the adsorbent was more than 10 times greater than sodium alginate. Scanning electron microscope image shows that an abundant amount of pore structure was successfully developed on adsorbents, promoting bacteria adsorption. In adsorbent assisted ABE fermentation, there was 21.64 g/L butanol in extracting layer compared to negligible butanol produced with only the extractant but without the adsorbent, for the reason that adsorbent can reduce damaging exposure of C. acetobutylicum to octanol. The strategy can improve total butanol production with respect to traditional culture approach by more than 2.5 fold and save energy for subsequent butanol recovery, which effects can potentially make the biobutanol production more economically practical.

Time-resolved electron transport in quantum-dot systems; Zeitaufgeloester Elektronentransport in Quantendotsystemen

Energy Technology Data Exchange (ETDEWEB)

Croy, Alexander

2010-06-30

In this thesis the time-resolved electron transport in quantum dot systems was studied. For this two different formalisms were presented: The nonequilibrium Green functions and the generalized quantum master equations. For both formalisms a propagation method for the numerical calculation of time-resolved expectation values, like the occupation and the electron current, was developed. For the demonstration of the propagation method two different question formulations were considered. On the one hand the stochastically driven resonant-level model was studied. On the other hand the pulse-induced transport through a double quantum dot was considered.

Time-Resolved PIV for Space-Time Correlations in Hot Jets

Science.gov (United States)

Wernet, Mark P.

2007-01-01

Temporally Resolved Particle Image Velocimetry (TR-PIV) is being used to characterize the decay of turbulence in jet flows a critical element for understanding the acoustic properties of the flow. A TR-PIV system, developed in-house at the NASA Glenn Research Center, is capable of acquiring planar PIV image frame pairs at up to 10 kHz. The data reported here were collected at Mach numbers of 0.5 and 0.9 and at temperature ratios of 0.89 and 1.76. The field of view of the TR-PIV system covered 6 nozzle diameters along the lip line of the 50.8 mm diameter jet. The cold flow data at Mach 0.5 were compared with hotwire anemometry measurements in order to validate the new TR-PIV technique. The axial turbulence profiles measured across the shear layer using TR-PIV were thinner than those measured using hotwire anemometry and remained centered along the nozzle lip line. The collected TR-PIV data illustrate the differences in the single point statistical flow properties of cold and hot jet flows. The planar, time-resolved velocity records were then used to compute two-point space-time correlations of the flow at the Mach 0.9 flow condition. The TR-PIV results show that there are differences in the convective velocity and growth rate of the turbulent structures between cold and hot flows at the same Mach number.

Time-resolved brightness measurements by streaking

Science.gov (United States)

Torrance, Joshua S.; Speirs, Rory W.; McCulloch, Andrew J.; Scholten, Robert E.

2018-03-01

Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

Gauge invariance in the theoretical description of time-resolved angle-resolved pump/probe photoemission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Freericks, J. K.; Krishnamurthy, H. R.; Sentef, M. A.; Devereaux, T. P.

2015-10-01

Nonequilibrium calculations in the presence of an electric field are usually performed in a gauge, and need to be transformed to reveal the gauge-invariant observables. In this work, we discuss the issue of gauge invariance in the context of time-resolved angle-resolved pump/probe photoemission. If the probe is applied while the pump is still on, one must ensure that the calculations of the observed photocurrent are gauge invariant. We also discuss the requirement of the photoemission signal to be positive and the relationship of this constraint to gauge invariance. We end by discussing some technical details related to the perturbative derivation of the photoemission spectra, which involve processes where the pump pulse photoexcites electrons due to nonequilibrium effects.

Multi-sensor in situ observations to resolve the sub-mesoscale features in the stratified Gulf of Finland, Baltic Sea

Science.gov (United States)

Lips, Urmas; Kikas, Villu; Liblik, Taavi; Lips, Inga

2016-05-01

High-resolution numerical modeling, remote sensing, and in situ data have revealed significant role of sub-mesoscale features in shaping the distribution pattern of tracers in the ocean's upper layer. However, in situ measurements are difficult to conduct with the required resolution and coverage in time and space to resolve the sub-mesoscale, especially in such relatively shallow basins as the Gulf of Finland, where the typical baroclinic Rossby radius is 2-5 km. To map the multi-scale spatiotemporal variability in the gulf, we initiated continuous measurements with autonomous devices, including a moored profiler and Ferrybox system, which were complemented by dedicated research-vessel-based surveys. The analysis of collected high-resolution data in the summers of 2009-2012 revealed pronounced variability at the sub-mesoscale in the presence of mesoscale upwelling/downwelling, fronts, and eddies. The horizontal wavenumber spectra of temperature variance in the surface layer had slopes close to -2 between the lateral scales from 10 to 0.5 km. Similar tendency towards the -2 slopes of horizontal wavenumber spectra of temperature variance was found in the seasonal thermocline between the lateral scales from 10 to 1 km. It suggests that the ageostrophic sub-mesoscale processes could contribute considerably to the energy cascade in such a stratified sea basin. We showed that the intrusions of water with different salinity, which indicate the occurrence of a layered flow structure, could appear in the process of upwelling/downwelling development and relaxation in response to variable wind forcing. We suggest that the sub-mesoscale processes play a major role in feeding surface blooms in the conditions of coupled coastal upwelling and downwelling events in the Gulf of Finland.

Time-resolved measurements with intense ultrashort laser pulses: a 'molecular movie' in real time

International Nuclear Information System (INIS)

Rudenko, A; Ergler, Th; Feuerstein, B; Zrost, K; Schroeter, C D; Moshammer, R; Ullrich, J

2007-01-01

We report on the high-resolution multidimensional real-time mapping of H 2 + and D 2 + nuclear wave packets performed employing time-resolved three-dimensional Coulomb explosion imaging with intense laser pulses. Exploiting a combination of a 'reaction microscope' spectrometer and a pump-probe setup with two intense 6-7 fs laser pulses, we simultaneously visualize both vibrational and rotational motion of the molecule, and obtain a sequence of snapshots of the squared ro-vibrational wave function with time-step resolution of ∼ 0.3 fs, allowing us to reconstruct a real-time movie of the ultrafast molecular motion. We observe fast dephasing, or 'collapse' of the vibrational wave packet and its subsequent revival, as well as signatures of rotational excitation. For D 2 + we resolve also the fractional revivals resulting from the interference between the counter-propagating parts of the wave packet

Decomposition of time-resolved tomographic PIV

NARCIS (Netherlands)

Schmid, P.J.; Violato, D.; Scarano, F.

2012-01-01

An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5,000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry capturing all relevant spatial and temporal scales. The measured threedimensional flow fields have

Time-resolved measurements of luminescence

Energy Technology Data Exchange (ETDEWEB)

Collier, Bradley B. [Department of Biomedical Engineering, 408 Mechanical Engineering Office Building, Spence Street, Texas A and M University, College Station, TX 77843 (United States); McShane, Michael J., E-mail: mcshane@tamu.edu [Department of Biomedical Engineering, 408 Mechanical Engineering Office Building, Spence Street, Texas A and M University, College Station, TX 77843 (United States); Materials Science and Engineering Program, 408 Mechanical Engineering Office Building, Spence Street, Texas A and M University, College Station, TX 77843 (United States)

2013-12-15

Luminescence sensing and imaging has become more widespread in recent years in a variety of industries including the biomedical and environmental fields. Measurements of luminescence lifetime hold inherent advantages over intensity-based response measurements, and advances in both technology and methods have enabled their use in a broader spectrum of applications including real-time medical diagnostics. This review will focus on recent advances in analytical methods, particularly calculation techniques, including time- and frequency-domain lifetime approaches as well as other time-resolved measurements of luminescence. -- Highlights: • Developments in technology have led to widespread use of luminescence lifetime. • Growing interest for sensing and imaging applications. • Recent advances in approaches to lifetime calculations are reviewed. • Advantages and disadvantages of various methods are weighed. • Other methods for measurement of luminescence lifetime also described.

Time-resolved measurements of luminescence

International Nuclear Information System (INIS)

Collier, Bradley B.; McShane, Michael J.

2013-01-01

Luminescence sensing and imaging has become more widespread in recent years in a variety of industries including the biomedical and environmental fields. Measurements of luminescence lifetime hold inherent advantages over intensity-based response measurements, and advances in both technology and methods have enabled their use in a broader spectrum of applications including real-time medical diagnostics. This review will focus on recent advances in analytical methods, particularly calculation techniques, including time- and frequency-domain lifetime approaches as well as other time-resolved measurements of luminescence. -- Highlights: • Developments in technology have led to widespread use of luminescence lifetime. • Growing interest for sensing and imaging applications. • Recent advances in approaches to lifetime calculations are reviewed. • Advantages and disadvantages of various methods are weighed. • Other methods for measurement of luminescence lifetime also described

Prospective time-resolved LCA of fully electric supercap vehicles in Germany.

Science.gov (United States)

Zimmermann, Benedikt M; Dura, Hanna; Baumann, Manuel J; Weil, Marcel R

2015-07-01

The ongoing transition of the German electricity supply toward a higher share of renewable and sustainable energy sources, called Energiewende in German, has led to dynamic changes in the environmental impact of electricity over the last few years. Prominent scenario studies predict that comparable dynamics will continue in the coming decades, which will further improve the environmental performance of Germany's electricity supply. Life cycle assessment (LCA) is the methodology commonly used to evaluate environmental performance. Previous LCA studies on electric vehicles have shown that the electricity supply for the vehicles' operation is responsible for the major part of their environmental impact. The core question of this study is how the prospective dynamic development of the German electricity mix will affect the impact of electric vehicles operated in Germany and how LCA can be adapted to analyze this impact in a more robust manner. The previously suggested approach of time-resolved LCA, which is located between static and dynamic LCA, is used in this study and compared with several static approaches. Furthermore, the uncertainty issue associated with scenario studies is addressed in general and in relation to time-resolved LCA. Two scenario studies relevant to policy making have been selected, but a moderate number of modifications have been necessary to adapt the data to the requirements of a life cycle inventory. A potential, fully electric vehicle powered by a supercapacitor energy storage system is used as a generic example. The results show that substantial improvements in the environmental repercussions of the electricity supply and, consequentially, of electric vehicles will be achieved between 2020 and 2031 on the basis of the energy mixes predicted in both studies. This study concludes that although scenarios might not be able to predict the future, they should nonetheless be used as data sources in prospective LCA studies, because in many cases

Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

Energy Technology Data Exchange (ETDEWEB)

Hohenberger, M., E-mail: mhoh@lle.rochester.edu; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Albert, F.; Palmer, N. E.; Döppner, T.; Divol, L.; Dewald, E. L.; Bachmann, B.; MacPhee, A. G.; LaCaille, G.; Bradley, D. K. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Lee, J. J. [National Security Technologies LLC, Livermore, California 94551 (United States)

2014-11-15

In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic–a multichannel, hard x-ray spectrometer operating in the 20–500 keV range–has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ∼300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U K{sub β}). The detectors impulse response function was measured in situ on NIF short-pulse (∼90 ps) experiments, and in off-line tests.

Time-resolved measurement of global synchronization in the dust acoustic wave

Science.gov (United States)

Williams, J. D.

2014-10-01

A spatially and temporally resolved measurement of the synchronization of the naturally occurring dust acoustic wave to an external drive and the relaxation from the driven wave mode back to the naturally occuring wave mode is presented. This measurement provides a time-resolved measurement of the synchronization of the self-excited dust acoustic wave with an external drive and the return to the self-excited mode. It is observed that the wave synchronizes to the external drive in a distinct time-dependent fashion, while there is an immediate loss of synchronization when the external modulation is discontinued.

Simultaneous in situ derivatization and ultrasound-assisted dispersive magnetic solid phase extraction for thiamine determination by spectrofluorimetry.

Science.gov (United States)

Tarigh, Ghazale Daneshvar; Shemirani, Farzaneh

2014-06-01

A simple and rapid method for the simultaneous in situ derivatizaion, preconcentration and extraction of thiamine (vitamin B1) as a model analyte was developed by a novel quantitative method, namely ultrasound-assisted dispersive magnetic solid phase extraction spectrofluorimetry (USA-DMSPE-FL) from different real samples. This method consists of sample preparation, in situ derivatization, exhaustive extraction and clean up by a single process. High extraction efficiency and in situ derivatization in a short period of time is the main advantages of this procedure. For this purpose, the reusable magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was used as an adsorbent for preconcentration and determination of thiamine. Thiamine was, simultaneously, in situ derivatized as thiochrome by potassium hexacyanoferrate (III) and adsorbed on MMWCNT in an ultrasonic water bath. The MMWCNTs were then collected using an external magnetic field. Subsequently, the extracted thiochrome was washed from the surface of the adsorbent and determined by spectrofluorimetry. The developed method, which has been analytically characterized under its optimal operating conditions, allows the detection of the analyte in the samples with method detection limits of 0.37 µg L(-1). The repeatability of the method, expressed as the relative standard deviation (RSD, n=6), varies between 2.0% and 4.8% in different real samples, while the enhancement factor is 197. The proposed procedure has been applied for the determination of thiamine in biological (serum and urine), pharmaceutical (multivitamin tablet and B complex syrup) and foodstuff samples (cereal, wheat flour, banana and honey) with the good recoveries in the range from 90% to 105%. Copyright © 2014 Elsevier B.V. All rights reserved.

Process for producing zeolite adsorbent and process for treating radioactive liquid waste with the zeolite adsorbent

International Nuclear Information System (INIS)

Motojima, K.; Kawamura, F.

1984-01-01

Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time

Timepix3 as X-ray detector for time resolved synchrotron experiments

Energy Technology Data Exchange (ETDEWEB)

Yousef, Hazem, E-mail: hazem.yousef@diamond.ac.uk; Crevatin, Giulio; Gimenez, Eva N.; Horswell, Ian; Omar, David; Tartoni, Nicola

2017-02-11

The Timepix3 ASIC can be used very effectively for time resolved experiments at synchrotron facilities. We have carried out characterizations with the synchrotron beam in order to determine the time resolution and other characteristics such as the energy resolution, charge sharing and signals overlapping. The best time resolution achieved is 19 ns FWHM for 12 keV photons and 350 V bias voltage. The time resolution shows dependency on the photon energy as well as on the chip and acquisition parameters. - Highlights: • An estimate time resolution of the Timepix3 is produced based on the arrival time. • At high resolution, the time structure of the DLS synchrotron beam is resolved. • The arrival time information improves combining the charge split events. • The results enable performing a wide range of time resolved experiments.

Timepix3 as X-ray detector for time resolved synchrotron experiments

International Nuclear Information System (INIS)

Yousef, Hazem; Crevatin, Giulio; Gimenez, Eva N.; Horswell, Ian; Omar, David; Tartoni, Nicola

2017-01-01

The Timepix3 ASIC can be used very effectively for time resolved experiments at synchrotron facilities. We have carried out characterizations with the synchrotron beam in order to determine the time resolution and other characteristics such as the energy resolution, charge sharing and signals overlapping. The best time resolution achieved is 19 ns FWHM for 12 keV photons and 350 V bias voltage. The time resolution shows dependency on the photon energy as well as on the chip and acquisition parameters. - Highlights: • An estimate time resolution of the Timepix3 is produced based on the arrival time. • At high resolution, the time structure of the DLS synchrotron beam is resolved. • The arrival time information improves combining the charge split events. • The results enable performing a wide range of time resolved experiments.

Time-Resolved Small-Angle X-Ray Scattering

NARCIS (Netherlands)

ten Elshof, Johan E.; Besselink, R.; Stawski, Tomasz; Castricum, H.L.; Levy, D.; Zayat, M.

2015-01-01

This chapter focuses on time-resolved studies of nanostructure development in sol-gel liquids, that is, diluted sols, wet gels, and drying thin fffilms. The most commonly investigated classes of sol-gel materials are silica, organically modified silica, template-directed mesostructured silica,

Time Resolved PIV for Space-Time Correlations in Hot Jets

Science.gov (United States)

Wernet, Mark P.

2007-01-01

Temporally Resolved Particle Image Velocimetry (TR-PIV) is the newest and most exciting tool recently developed to support our continuing efforts to characterize and improve our understanding of the decay of turbulence in jet flows -- a critical element for understanding the acoustic properties of the flow. A new TR-PIV system has been developed at the NASA Glenn Research Center which is capable of acquiring planar PIV image frame pairs at up to 25 kHz. The data reported here were collected at Mach numbers of 0.5 and 0.9 and at temperature ratios of 0.89 and 1.76. The field of view of the TR-PIV system covered 6 nozzle diameters along the lip line of the 50.8 mm diameter jet. The cold flow data at Mach 0.5 were compared with hotwire anemometry measurements in order to validate the new TR-PIV technique. The axial turbulence profiles measured across the shear layer using TR-PIV were thinner than those measured using hotwire anemometry and remained centered along the nozzle lip line. The collected TR-PIV data illustrate the differences in the single point statistical flow properties of cold and hot jet flows. The planar, time-resolved velocity records were then used to compute two-point space-time correlations of the flow at the Mach 0.9 flow condition. The TR-PIV results show that there are differences in the convective velocity and growth rate of the turbulent structures between cold and hot flows at the same Mach number

Time-Resolved Hard X-Ray Spectrometer

International Nuclear Information System (INIS)

Kenneth Moya; Ian McKennaa; Thomas Keenana; Michael Cuneob

2007-01-01

Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and polar views. UNSPEC1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment

Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures

DEFF Research Database (Denmark)

Schnadt, Joachim; Xu, Wei; Vang, Ronnie Thorbjørn

2010-01-01

a large tolerance to monatomic surface steps on the Ag(110) surface. The observed behaviour is explained in terms of strong intermolecular hydrogen bonding and a strong surface-mediated directionality, assisted by a sufficient degree of molecular backbone flexibility. In contrast, the same kind of step......-edge crossing is not observed when the molecules are adsorbed on the isotropic Ag(111) or more reactive Cu(110) surfaces. On Ag(111), similar 1-D assemblies are formed to those on Ag(110), but they are oriented along the step edges. On Cu(110), the carboxylic groups of NDCA are deprotonated and form covalent...... bonds to the surface, a situation which is also achieved on Ag(110) by annealing to 200 degrees C. These results show that the formation of particular self-assembled molecular nanostructures depends significantly on a subtle balance between the adsorbate-adsorbate and adsorbate-substrate interactions...

In situ investigation of dye adsorption on TiO2 films using a quartz crystal microbalance with a dissipation technique

KAUST Repository

Harms, Hauke A.

2012-01-01

Dye adsorption plays a crucial role in dye-sensitized solar cells. Herein, we demonstrate an in situ liquid-phase analytical technique to quantify in real time adsorption of dye and coadsorbates on flat and mesoporous TiO 2 films. For the first time, a molar ratio of co-adsorbed Y123 and chenodeoxycholic acid has been measured. © 2012 the Owner Societies.

Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

International Nuclear Information System (INIS)

Delgado, Jose Manuel; Blanco, Raquel; Orts, Jose Manuel; Perez, Juan Manuel; Rodes, Antonio

2010-01-01

The adsorption of glycolate anions at sputtered gold thin-film electrodes was studied in perchloric acid solutions by cyclic voltammetry experiments combined with in situ Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Reflection Absorption Spectroscopy under attenuated total reflection conditions (ATR-SEIRAS). Theoretical harmonic vibrational frequencies and band intensities obtained from B3LYP/LANL2DZ,6-31+G(d) calculations for glycolate species adsorbed on Au clusters with (1 1 1) orientation were used to interpret the experimental spectra. Vibrational data confirm the bidentate bonding of glycolate anions through the oxygen atoms of the carboxylate group, in a bridge configuration with the OCO plane perpendicular to the metal surface. The DFT calculations show no significant effect of the total charge of the metal cluster-adsorbate adduct on the vibrational frequencies of adsorbed glycolate species. The infrared experimental study is extended to platinum films electrochemically deposited onto sputtered gold thin-film electrodes showing the potential-dependent formation of adsorbed CO upon dissociative adsorption of glycolate anions. As in the case of gold, the reversible adsorption of glycolate anions takes place in a bidentate configuration as predicted by DFT calculations for glycolate adsorbed on Pt(1 1 1) clusters. At low glycolic acid concentration, the in situ ATR-SEIRA spectra evidence the formation of adsorbed oxalate as reaction intermediate.

Adherence of platelets to in situ albumin-binding surfaces under flow conditions: role of surface-adsorbed albumin

International Nuclear Information System (INIS)

Guha Thakurta, Sanjukta; Miller, Robert; Subramanian, Anuradha

2012-01-01

Surfaces that preferentially bind human serum albumin (HSA) were generated by grafting albumin-binding linear peptide (LP1) onto silicon surfaces. The research aim was to evaluate the adsorption pattern of proteins and the adhesion of platelets from platelet-poor plasma and platelet-rich plasma, respectively, by albumin-binding surfaces under physiological shear rate (96 and 319 s −1 ) conditions. Bound proteins were quantified using enzyme-linked immunosorbent assays (ELISAs) and two-dimensional gel electrophoresis. A ratio of ∼1000:100:1 of adsorbed HSA, human immunoglobulin (HIgG) and human fibrinogen (HFib) was noted, respectively, on LP1-functionalized surfaces, and a ratio of ∼5:2:1 of the same was noted on control surfaces, as confirmed by ELISAs. The surface-adsorbed von Willebrand factor was undetectable by sensitive ELISAs. The amount of adhered platelets correlated with the ratio of adsorbed HSA/HFib. Platelet morphology was more rounded on LP1-functionalized surfaces when compared to control surfaces. The platelet adhesion response on albumin-binding surfaces can be explained by the reduction in the co-adsorption of other plasma proteins in a surface environment where there is an excess of albumin molecules, coupled with restrictions in the conformational transitions of other surface-adsorbed proteins into hemostatically active forms. (paper)

Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation

OpenAIRE

Schroeder, Jeremy; Thomson, W.; Howard, B.; Schell, N.; Näslund, Lars-Åke; Rogström, Lina; Johansson-Jöesaar, Mats P.; Ghafoor, Naureen; Odén, Magnus; Nothnagel, E.; Shepard, A.; Greer, J.; Birch, Jens

2015-01-01

We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (greater than50 keV), high photon flux (greater than10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (less than1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation...

Time-resolved pump-probe experiments at the LCLS

Energy Technology Data Exchange (ETDEWEB)

Glownia, James; /SLAC /Stanford U., Appl. Phys. Dept.; Cryan, J.; /SLAC /Stanford U., Phys. Dept.; Andreasson, J.; /Uppsala U.; Belkacem, A.; /LBNL, Berkeley; Berrah, N.; /Western Michigan U.; Blaga, C.L.; /Ohio State U.; Bostedt, C.; Bozek, J.; /SLAC; DiMauro, L.F.; /Ohio State U.; Fang, L.; /Western Michigan U.; Frisch, J.; /SLAC; Gessner, O.; /LBNL; Guhr, M.; /SLAC; Hajdu, J.; /Uppsala U.; Hertlein, M.P.; /LBNL; Hoener, M.; /Western Michigan U. /LBNL; Huang, G.; Kornilov, O.; /LBNL; Marangos, J.P.; /Imperial Coll., London; March, A.M.; /Argonne; McFarland, B.K.; /SLAC /Stanford U., Phys. Dept. /SLAC /IRAMIS, Saclay /Stanford U., Phys. Dept. /Georgia Tech /Argonne /Kansas State U. /SLAC /Stanford U., Phys. Dept. /SLAC /Stanford U., Appl. Phys. Dept. /Stanford U., Appl. Phys. Dept. /SLAC /LBNL /Argonne /SLAC /SLAC /Stanford U., Appl. Phys. Dept. /Stanford U., Phys. Dept.

2011-08-12

The first time-resolved x-ray/optical pump-probe experiments at the SLAC Linac Coherent Light Source (LCLS) used a combination of feedback methods and post-analysis binning techniques to synchronize an ultrafast optical laser to the linac-based x-ray laser. Transient molecular nitrogen alignment revival features were resolved in time-dependent x-ray-induced fragmentation spectra. These alignment features were used to find the temporal overlap of the pump and probe pulses. The strong-field dissociation of x-ray generated quasi-bound molecular dications was used to establish the residual timing jitter. This analysis shows that the relative arrival time of the Ti:Sapphire laser and the x-ray pulses had a distribution with a standard deviation of approximately 120 fs. The largest contribution to the jitter noise spectrum was the locking of the laser oscillator to the reference RF of the accelerator, which suggests that simple technical improvements could reduce the jitter to better than 50 fs.

Time Resolved Broadband Terahertz Relaxation Dynamics of Electron in Water

DEFF Research Database (Denmark)

Wang, Tianwu; Iwaszczuk, Krzysztof; Cooke, David G.

We investigated the transient response of the solvated electron in water ejected by photodetachment from potassium ferrocyanide using time resolved terahertz spectroscopy (TSTS). Ultrabroadband THz transients are generated and detected by a two-color femtosecond-induced air plasma and air biased...

Spatially-resolved measurement of optically stimulated luminescence and time-resolved luminescence

International Nuclear Information System (INIS)

Bailiff, I.K.; Mikhailik, V.B.

2003-01-01

Spatially-resolved measurements of optically stimulated luminescence (OSL) were performed using a two-dimensional scanning system designed for use with planar samples. The scanning system employs a focused laser beam to stimulate a selected area of the sample, which is moved under the beam by a motorised stage. Exposure of the sample is controlled by an electronic shutter. Mapping of the distribution of OSL using a continuous wave laser source was obtained with sub-millimeter resolution for samples of sliced brick, synthetic single crystal quartz, concrete and dental ceramic. These revealed sporadic emission in the case of brick or concrete and significant spatial variation of emission for quartz and dental ceramic slices. Determinations of absorbed dose were performed for quartz grains within a slice of modern brick. Reconfiguration of the scanner with a pulsed laser source enabled quartz and feldspathic minerals within a ceramic sample to be thinner region. about 6 nm from the extrapolation of themeasuring the time-resolved luminescence spectrum

Watching proteins function with time-resolved x-ray crystallography

Science.gov (United States)

Šrajer, Vukica; Schmidt, Marius

2017-09-01

Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol. 305 115-54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201-41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol. 22 651-9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237-51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5-20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242-6, Barends et al 2015 Science 350 445-50, Pande et al 2016 Science 352 725-9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs. We also outline

Shock compression and flash-heating of molecular adsorbates on the picosecond time scale

Science.gov (United States)

Berg, Christopher Michael

An ultrafast nonlinear coherent laser spectroscopy termed broadband multiplex vibrational sum-frequency generation (SFG) with nonresonant suppression was employed to monitor vibrational transitions of molecular adsorbates on metallic substrates during laser-driven shock compression and flash-heating. Adsorbates were in the form of well-ordered self-assembled monolayers (SAMs) and included molecular explosive simulants, such as nitroaromatics, and long chain-length alkanethiols. Based on reflectance measurements of the metallic substrates, femtosecond flash-heating pulses were capable of producing large-amplitude temperature jumps with DeltaT = 500 K. Laser-driven shock compression of SAMs produced pressures up to 2 GPa, where 1 GPa ≈ 1 x 104 atm. Shock pressures were estimated via comparison with frequency shifts observed in the monolayer vibrational transitions during hydrostatic pressure measurements in a SiC anvil cell. Molecular dynamics during flash-heating and shock loading were probed with vibrational SFG spectroscopy with picosecond temporal resolution and sub-nanometer spatial resolution. Flash-heating studies of 4-nitrobenzenethiolate (NBT) on Au provided insight into effects from hot-electron excitation of the molecular adsorbates at early pump-probe delay times. At longer delay times, effects from the excitation of SAM lattice modes and lower-energy NBT vibrations were shown. In addition, flash-heating studies of alkanethiolates demonstrated chain disordering behaviors as well as interface thermal conductances across the Au-SAM junction, which was of specific interest within the context of molecular electronics. Shock compression studies of molecular explosive simulants, such as 4-nitrobenzoate (NBA), demonstrated the proficiency of this technique to observe shock-induced molecular dynamics, in this case orientational dynamics, on the picosecond time scale. Results validated the utilization of these refined shock loading techniques to probe the shock

Time-resolved diffusion tomographic imaging in highly scattering turbid media

Science.gov (United States)

Alfano, Robert R. (Inventor); Cai, Wei (Inventor); Liu, Feng (Inventor); Lax, Melvin (Inventor); Das, Bidyut B. (Inventor)

1998-01-01

A method for imaging objects in highly scattering turbid media. According to one embodiment of the invention, the method involves using a plurality of intersecting source/detectors sets and time-resolving equipment to generate a plurality of time-resolved intensity curves for the diffusive component of light emergent from the medium. For each of the curves, the intensities at a plurality of times are then inputted into the following inverse reconstruction algorithm to form an image of the medium: X.sup.(k+1).spsp.T =?Y.sup.T W+X.sup.(k).spsp.T .LAMBDA.!?W.sup.T W+.LAMBDA.!.sup.-1 wherein W is a matrix relating output at detector position r.sub.d, at time t, to source at position r.sub.s, .LAMBDA. is a regularization matrix, chosen for convenience to be diagonal, but selected in a way related to the ratio of the noise, to fluctuations in the absorption (or diffusion) X.sub.j that we are trying to determine: .LAMBDA..sub.ij =.lambda..sub.j .delta..sub.ij with .lambda..sub.j =/ Here Y is the data collected at the detectors, and X.sup.k is the kth iterate toward the desired absoption information.

Difference structures from time-resolved small-angle and wide-angle x-ray scattering

Science.gov (United States)

Nepal, Prakash; Saldin, D. K.

2018-05-01

Time-resolved small-angle x-ray scattering/wide-angle x-ray scattering (SAXS/WAXS) is capable of recovering difference structures directly from difference SAXS/WAXS curves. It does so by means of the theory described here because the structural changes in pump-probe detection in a typical time-resolved experiment are generally small enough to be confined to a single residue or group in close proximity which is identified by a method akin to the difference Fourier method of time-resolved crystallography. If it is assumed, as is usual with time-resolved structures, that the moved atoms lie within the residue, the 100-fold reduction in the search space (assuming a typical protein has about 100 residues) allows the exaction of the structure by a simulated annealing algorithm with a huge reduction in computing time and leads to a greater resolution by varying the positions of atoms only within that residue. This reduction in the number of potential moved atoms allows us to identify the actual motions of the individual atoms. In the case of a crystal, time-resolved calculations are normally performed using the difference Fourier method, which is, of course, not directly applicable to SAXS/WAXS. The method developed in this paper may be thought of as a substitute for that method which allows SAXS/WAXS (and hence disordered molecules) to also be used for time-resolved structural work.

Spin and time-resolved magnetic resonance in radiation chemistry. Recent developments and perspectives

International Nuclear Information System (INIS)

Shkrob, I.A.; Trifunac, A.D.

1997-01-01

Time-resolved pulsed EPR and ODMR in studies on early events in radiation chemistry are examined. It is concluded that these techniques yield valuable and diverse information about chemical reactions in spurs, despite the fact that the spur reactions occur on a time scale that is much shorter than the time resolution of these methods. Several recent examples include EPR of H/D atoms in vitreous silica and cryogenic liquids and ODMR of doped alkane solids and amorphous semiconductors. It is argued that a wider use of time-resolved magnetic resonance methods would benefit the studies on radiation chemistry of disordered solids, simple liquids, and polymers. (author)

Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

International Nuclear Information System (INIS)

Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W.P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

2015-01-01

-flow natural seawater at the Pacific Northwest National Laboratory (PNNL). Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis were used to characterize the adsorbent at different stages of adsorbent preparation and treatment. The study can be divided into two parts: (A) investigation of optimal parameters for KOH adsorbent conditioning and (B) investigation of other possible agents for alkali conditioning, including cost analysis on the basis of uranium production. In the first part of the study, tests with simulated seawater containing 8 ppm uranium showed that the uranium adsorption capacity increased with an increase in the KOH concentration and conditioning time and temperature at each of the KOH concentrations used. FTIR and solid state NMR studies indicated that KOH conditioning converts the amidoxime functional groups into more hydrophilic carboxylate. The longer the KOH conditioning time, up to three hours, the higher was the loading capacity from the simulated seawater solution which is composed of only uranyl, sodium, chloride, and carbonate ions. Marine testing with natural seawater, on the other hand, showed that the uranium adsorption capacity of the adsorbent increased with KOH conditioning temperature, and gradually decreased with increasing KOH conditioning time from one hour to three hours at 80 C. This behavior is due to the conversion of amidoxime to carboxylate. The carboxylate groups are needed to increase the hydrophilicity of the adsorbent; however, conversion of a significant amount of amidoxime to carboxylate leads to loss in selectivity toward uranyl ions. Thus, there is an optimum KOH conditioning time for each temperature at which an optimum ratio between amidoxime and carboxylate is reached. For the case of base conditioning with 0.44 M KOH at 80 C, the optimal conditioning time is 1 hour, with respect to the highest uranium loading capacity from

Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

Energy Technology Data Exchange (ETDEWEB)

Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

2015-09-30

-flow natural seawater at the Pacific Northwest National Laboratory (PNNL). Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR) spectroscopy, Scanning Electron Microscopy (SEM), and elemental analysis were used to characterize the adsorbent at different stages of adsorbent preparation and treatment. The study can be divided into two parts: (A) investigation of optimal parameters for KOH adsorbent conditioning and (B) investigation of other possible agents for alkali conditioning, including cost analysis on the basis of uranium production. In the first part of the study, tests with simulated seawater containing 8 ppm uranium showed that the uranium adsorption capacity increased with an increase in the KOH concentration and conditioning time and temperature at each of the KOH concentrations used. FTIR and solid state NMR studies indicated that KOH conditioning converts the amidoxime functional groups into more hydrophilic carboxylate. The longer the KOH conditioning time, up to three hours, the higher was the loading capacity from the simulated seawater solution which is composed of only uranyl, sodium, chloride, and carbonate ions. Marine testing with natural seawater, on the other hand, showed that the uranium adsorption capacity of the adsorbent increased with KOH conditioning temperature, and gradually decreased with increasing KOH conditioning time from one hour to three hours at 80 C. This behavior is due to the conversion of amidoxime to carboxylate. The carboxylate groups are needed to increase the hydrophilicity of the adsorbent; however, conversion of a significant amount of amidoxime to carboxylate leads to loss in selectivity toward uranyl ions. Thus, there is an optimum KOH conditioning time for each temperature at which an optimum ratio between amidoxime and carboxylate is reached. For the case of base conditioning with 0.44 M KOH at 80 C, the optimal conditioning time is 1 hour, with respect to the highest uranium loading capacity from

Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

DEFF Research Database (Denmark)

Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank

2016-01-01

Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IR...

A fiber optics system for monitoring utilization of ZnO adsorbent beds during desulfurization for logistic fuel cell applications

Science.gov (United States)

Sujan, Achintya; Yang, Hongyun; Dimick, Paul; Tatarchuk, Bruce J.

2016-05-01

An in-situ fiber optic based technique for direct measurement of capacity utilization of ZnO adsorbent beds by monitoring bed color changes during desulfurization for fuel cell systems is presented. Adsorbents composed of bulk metal oxides (ZnO) and supported metal oxides (ZnO/SiO2 and Cusbnd ZnO/SiO2) for H2S removal at 22 °C are examined. Adsorbent bed utilization at breakthrough is determined by the optical sensor as the maximum derivative of area under UV-vis spectrum from 250 to 800 nm observed as a function of service time. Since the response time of the sensor due to bed color change is close to bed breakthrough time, a series of probes along the bed predicts utilization of the portion of bed prior to H2S breakthrough. The efficacy of the optical sensor is evaluated as a function of inlet H2S concentration, H2S flow rate and desulfurization in presence of CO, CO2 and moisture in feed. A 6 mm optical probe is employed to measure utilization of a 3/16 inch ZnO extrudate bed for H2S removal. It is envisioned that with the application of the optical sensor, desulfurization can be carried out at high adsorbent utilization and low operational costs during on-board miniaturized fuel processing for logistic fuel cell power systems.

Multi-frame pyramid correlation for time-resolved PIV

NARCIS (Netherlands)

Sciacchitano, A.; Scarano, F.; Wieneke, B.

2012-01-01

A novel technique is introduced to increase the precision and robustness of time-resolved particle image velocimetry (TR-PIV) measurements. The innovative element of the technique is the linear combination of the correlation signal computed at different separation time intervals. The domain of the

Transporting method for adsorbing tower and the adsorbing tower

International Nuclear Information System (INIS)

Shimokawa, Nobuhiro.

1996-01-01

A cylindrical plastic bag is disposed to the upper surface of an adsorbing tower so as to surround a suspending piece. One opening of the bag is sealed, and other opening is secured in a sealed state to a bag holding portion disposed to glove box at a gate for the adsorbing tower box. The adsorbing tower is transported into the glove box, and after the completion of the operation of the adsorbing tower, the adsorbing tower is taken out in a state that the bag is restricted and sealed at a portion below the adsorbing tower. The bag may be made of a vinyl plastic, the bag holding portion may be a short-cylindrical protrusion, and may have an O-ring groove at the outer surface. Even if the adsorbing tower is heavy, the adsorbing tower can be carried out easily in a state where it is sealed gas tightly. (N.H.)

Multi-Channel Amplifier-Discriminator for Highly Time-Resolved Detection

CERN Document Server

Despeisse, M; Lapington, J; Jarron, P

2011-01-01

A low-power multi-channel amplifier-discriminator was developed for application in highly time-resolved detection systems. The proposed circuit architecture, so-called Nino, is based on a time-over-threshold approach and shows a high potential for time-resolved readout of solid-state photo-detectors and of detectors based on vacuum technologies. The Irpics circuit was designed in a 250 nm CMOS technology, implementing 32 channels of a Nino version optimized to achieve high-time resolution on the output low-voltage differential signals (LVDS) while keeping a low power consumption of 10 mW per channel. Electrical characterizations of the circuit demonstrate a very low intrinsic time jitter on the output pulse leading edge, measured below 10 ps rms for each channel for high input signal charges (100 fC) and below 25 ps rms for low input signal charges (20-100 fC). The read-out architecture moreover permits to retrieve the input signal charge from the timing measurements, while a calibration procedure was develop...

Reduction of Poisson noise in measured time-resolved data for time-domain diffuse optical tomography.

Science.gov (United States)

Okawa, S; Endo, Y; Hoshi, Y; Yamada, Y

2012-01-01

A method to reduce noise for time-domain diffuse optical tomography (DOT) is proposed. Poisson noise which contaminates time-resolved photon counting data is reduced by use of maximum a posteriori estimation. The noise-free data are modeled as a Markov random process, and the measured time-resolved data are assumed as Poisson distributed random variables. The posterior probability of the occurrence of the noise-free data is formulated. By maximizing the probability, the noise-free data are estimated, and the Poisson noise is reduced as a result. The performances of the Poisson noise reduction are demonstrated in some experiments of the image reconstruction of time-domain DOT. In simulations, the proposed method reduces the relative error between the noise-free and noisy data to about one thirtieth, and the reconstructed DOT image was smoothed by the proposed noise reduction. The variance of the reconstructed absorption coefficients decreased by 22% in a phantom experiment. The quality of DOT, which can be applied to breast cancer screening etc., is improved by the proposed noise reduction.

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

International Nuclear Information System (INIS)

Rutherford, Michael E.; Chapman, David J.; White, Thomas G.; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E.

2016-01-01

Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

Energy Technology Data Exchange (ETDEWEB)

Rutherford, Michael E.; Chapman, David J.; White, Thomas G. [Imperial College London, London (United Kingdom); Drakopoulos, Michael [Diamond Light Source, I12 Joint Engineering, Environmental, Processing (JEEP) Beamline, Didcot, Oxfordshire (United Kingdom); Rack, Alexander [European Synchrotron Radiation Facility, Grenoble (France); Eakins, Daniel E., E-mail: d.eakins@imperial.ac.uk [Imperial College London, London (United Kingdom)

2016-03-24

Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

Usefulness of time-resolved projection MRA on evaluation of hemodynamics in cerebral occlusive diseases

International Nuclear Information System (INIS)

Oka, Yoshihisa; Kusunoki, Katsusuke; Nochide, Ichiro; Igase, Keiji; Harada, Hironobu; Sadamoto, Kazuhiko; Nagasawa, Kiyoshi

2001-01-01

The usefulness for evaluation of cerebral hemodynamics using time-resolved projection MRA was studied in normal volunteers and patients of cerebrovascular diseases. Six normal volunteers and ten patients with cerebrovascular occlusive diseases including 6 of IC occlusion and 4 of post EC/IC bypass surgery underwent time-resolved projection MRA on a 1.5 T clinical MRI system. Projection angiograms are acquired with 2D-fast SPGR sequence with a time resolution of approximately one image per second, 40 images being acquired consecutively before and after bolus injection Gd-DTPA. And all images were calculated by complex subtraction from the background mask in a work station. In normal volunteers, the quality of images of time-resolved projection MRA was satisfactory. The arteries from internal carotid artery through M2 segment of middle cerebral artery and all major venous systems were well portrayed. In 4 cases of IC occlusion who were assessed the collateral flow through the anterior communicating artery and posterior communicating artery, there were delayed to demonstrate the ipsilateral MCA. However, in 2 cases of IC occlusion that were assessed the collateral flow through leptomeningeal anastomosis, ipsilateral MCA and collateral circulation were not demonstrated. In all patients of post EC/IC bypass surgery, the patency of EC/IC bypass could be evaluated as properly with time-resolved projection MRA as 3D-TOF MRA. Although the temporal and spatial resolutions are insufficient, time-resolved projection MRA was power-full non-invasive method to evaluate the cerebral hemodynamics vis the basal communicating arteries in IC occlusion and identify the patency of EC/IC bypass. (author)

Broad-band time-resolved near infrared spectroscopy in the TJ-II stellarator

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, M.C.; Pastor, I.; Cal, E. de la; McCarthy, K.J. [Laboratorio Nacional de Fusion, CIEMAT, Madrid (Spain); Diaz, D. [Universidad Autonoma de Madrid, Dept Quimica Fisica Aplicada, Madrid (Spain)

2014-11-15

First experimental results on broad-band, time-resolved Near Infrared (NIR;here loosely defined as covering from 750 to 1650 nm) passive spectroscopy using a high sensitivity InGaAs detector are reported for the TJ-II Stellarator. Experimental set-up is described together with its main characteristics, the most remarkable ones being its enhanced NIR response, broadband spectrum acquisition in a single shot, and time-resolved measurements with up to 1.8 kHz spectral rate. Prospects for future work and more extended physics studies in this newly open spectral region in TJ-II are discussed. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

In-situ biofouling assessment in spacer filled channels using optical coherence tomography (OCT): 3D biofilm thickness mapping

KAUST Repository

Fortunato, Luca

2017-01-13

Membrane systems for water purification can be seriously hampered by biofouling. The use of optical coherence tomography (OCT) to investigate biofilms in membrane systems has recently increased due to the ability to do the characterization in-situ and non-destructively The OCT biofilm thickness map is presented for the first time as a tool to assess biofilm spatial distribution on a surface. The map allows the visualization and evaluation of the biofilm formation and growth in membrane filtration systems through the use of a false color scale. The biofilm development was monitored with OCT to evaluate the suitability of the proposed approach. A 3D time series analysis of biofilm development in a spacer filled channel representative of a spiral-wound membrane element was performed. The biofilm thickness map enables the time-resolved and spatial-resolved evaluation and visualization of the biofilm deposition pattern in-situ non-destructively.

Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111

Directory of Open Access Journals (Sweden)

A. Schuler

2017-01-01

Full Text Available Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3′,5,5′-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111 in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

Quantum-dot-based homogeneous time-resolved fluoroimmunoassay of alpha-fetoprotein

Energy Technology Data Exchange (ETDEWEB)

Chen Meijun; Wu Yingsong; Lin Guanfeng; Hou Jingyuan; Li Ming [Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, Guangzhou, 510515 (China); Liu Tiancai, E-mail: liutc@smu.edu.cn [Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, Guangzhou, 510515 (China)

2012-09-05

Highlights: Black-Right-Pointing-Pointer QDs-based homogeneous time-resolved fluoroimmunoassay was developed to detect AFP. Black-Right-Pointing-Pointer The conjugates were prepared with QDs-doped microspheres and anti-AFP McAb. Black-Right-Pointing-Pointer The conjugates were prepared with LTCs and another anti-AFP McAb. Black-Right-Pointing-Pointer Excess amounts of conjugates were used for detecting AFP without rinsing. Black-Right-Pointing-Pointer The wedding of QPs and LTCs was suitable for HTRFIA to detect AFP. - Abstract: Quantum dots (QDs) with novel photoproperties are not widely used in clinic diagnosis, and homogeneous time-resolved fluorescence assays possess many advantages over current methods for alpha-fetoprotein (AFP) detection. A novel QD-based homogeneous time-resolved fluorescence assay was developed and used for detection of AFP, a primary marker for many cancers and diseases. QD-doped carboxyl-modified polystyrene microparticles (QPs) were prepared by doping oil-soluble QDs possessing a 605 nm emission peak. The antibody conjugates (QPs-E014) were prepared from QPs and an anti-AFP monoclonal antibody, and luminescent terbium chelates (LTCs) were prepared and conjugated to a second anti-AFP monoclonal antibody (LTCs-E010). In a double-antibodies sandwich structure, QPs-E014 and LTCs-E010 were used for detection of AFP, serving as energy acceptor and donor, respectively, with an AFP bridge. The results demonstrated that the luminescence lifetime of these QPs was sufficiently long for use in a time-resolved fluoroassay, with the efficiency of time-resolved Foerster resonance transfer (TR-FRET) at 67.3% and the spatial distance of the donor to acceptor calculated to be 66.1 Angstrom-Sign . Signals from TR-FRET were found to be proportional to AFP concentrations. The resulting standard curve was log Y = 3.65786 + 0.43863{center_dot}log X (R = 0.996) with Y the QPs fluorescence intensity and X the AFP concentration; the calculated sensitivity was 0

Watching proteins function with time-resolved x-ray crystallography

Energy Technology Data Exchange (ETDEWEB)

Šrajer, Vukica; Schmidt, Marius

2017-08-22

Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol. 305 115–54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201–41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol. 22 651–9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237–51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5–20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242–6, Barends et al 2015 Science 350 445–50, Pande et al 2016 Science 352 725–9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs. We

Watching proteins function with time-resolved x-ray crystallography

International Nuclear Information System (INIS)

Šrajer, Vukica; Schmidt, Marius

2017-01-01

Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol . 305 115–54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201–41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol . 22 651–9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237–51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5–20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242–6, Barends et al 2015 Science 350 445–50, Pande et al 2016 Science 352 725–9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs

The time resolved SBS and SRS research in heavy water and its application in CARS

Science.gov (United States)

Liu, Jinbo; Gai, Baodong; Yuan, Hong; Sun, Jianfeng; Zhou, Xin; Liu, Di; Xia, Xusheng; Wang, Pengyuan; Hu, Shu; Chen, Ying; Guo, Jingwei; Jin, Yuqi; Sang, Fengting

2018-05-01

We present the time-resolved character of stimulated Brillouin scattering (SBS) and backward stimulated Raman scattering (BSRS) in heavy water and its application in Coherent Anti-Stokes Raman Scattering (CARS) technique. A nanosecond laser from a frequency-doubled Nd: YAG laser is introduced into a heavy water cell, to generate SBS and BSRS beams. The SBS and BSRS beams are collinear, and their time resolved characters are studied by a streak camera, experiment show that they are ideal source for an alignment-free CARS system, and the time resolved property of SBS and BSRS beams could affect the CARS efficiency significantly. By inserting a Dye cuvette to the collinear beams, the time-overlapping of SBS and BSRS could be improved, and finally the CARS efficiency is increased, even though the SBS energy is decreased. Possible methods to improve the efficiency of this CARS system are discussed too.

Spatially-resolved in-situ quantification of biofouling using optical coherence tomography (OCT) and 3D image analysis in a spacer filled channel

KAUST Repository

Fortunato, Luca

2016-11-21

The use of optical coherence tomography (OCT) to investigate biomass in membrane systems has increased with time. OCT is able to characterize the biomass in-situ and non-destructively. In this study, a novel approach to process three-dimensional (3D) OCT scans is proposed. The approach allows obtaining spatially-resolved detailed structural biomass information. The 3D biomass reconstruction enables analysis of the biomass only, obtained by subtracting the time zero scan to all images. A 3D time series analysis of biomass development in a spacer filled channel under representative conditions (cross flow velocity) for a spiral wound membrane element was performed. The flow cell was operated for five days with monitoring of ultrafiltration membrane performance: feed channel pressure drop and permeate flux. The biomass development in the flow cell was detected by OCT before a performance decline was observed. Feed channel pressure drop continuously increased with increasing biomass volume, while flux decline was mainly affected in the initial phase of biomass accumulation. The novel OCT imaging approach enabled the assessment of spatial biomass distribution in the flow cell, discriminating the total biomass volume between the membrane, feed spacer and glass window. Biomass accumulation was stronger on the feed spacer during the early stage of biofouling, impacting the feed channel pressure drop stronger than permeate flux.

Reactor for in situ measurements of spatially resolved kinetic data in heterogeneous catalysis

Science.gov (United States)

Horn, R.; Korup, O.; Geske, M.; Zavyalova, U.; Oprea, I.; Schlögl, R.

2010-06-01

The present work describes a reactor that allows in situ measurements of spatially resolved kinetic data in heterogeneous catalysis. The reactor design allows measurements up to temperatures of 1300 °C and 45 bar pressure, i.e., conditions of industrial relevance. The reactor involves reactants flowing through a solid catalyst bed containing a sampling capillary with a side sampling orifice through which a small fraction of the reacting fluid (gas or liquid) is transferred into an analytical device (e.g., mass spectrometer, gas chromatograph, high pressure liquid chromatograph) for quantitative analysis. The sampling capillary can be moved with μm resolution in or against flow direction to measure species profiles through the catalyst bed. Rotation of the sampling capillary allows averaging over several scan lines. The position of the sampling orifice is such that the capillary channel through the catalyst bed remains always occupied by the capillary preventing flow disturbance and fluid bypassing. The second function of the sampling capillary is to provide a well which can accommodate temperature probes such as a thermocouple or a pyrometer fiber. If a thermocouple is inserted in the sampling capillary and aligned with the sampling orifice fluid temperature profiles can be measured. A pyrometer fiber can be used to measure the temperature profile of the solid catalyst bed. Spatial profile measurements are demonstrated for methane oxidation on Pt and methane oxidative coupling on Li/MgO, both catalysts supported on reticulated α -Al2O3 foam supports.

Time-resolved temperature measurements in a rapid compression machine using quantum cascade laser absorption in the intrapulse mode

KAUST Repository

Nasir, Ehson Fawad

2016-07-16

A temperature sensor based on the intrapulse absorption spectroscopy technique has been developed to measure in situ temperature time-histories in a rapid compression machine (RCM). Two quantum-cascade lasers (QCLs) emitting near 4.55μm and 4.89μm were operated in pulsed mode, causing a frequency "down-chirp" across two ro-vibrational transitions of carbon monoxide. The down-chirp phenomenon resulted in large spectral tuning (δν ∼2.8cm-1) within a single pulse of each laser at a high pulse repetition frequency (100kHz). The wide tuning range allowed the application of the two-line thermometry technique, thus making the sensor quantitative and calibration-free. The sensor was first tested in non-reactive CO-N2 gas mixtures in the RCM and then applied to cases of n-pentane oxidation. Experiments were carried out for end of compression (EOC) pressures and temperatures ranging 9.21-15.32bar and 745-827K, respectively. Measured EOC temperatures agreed with isentropic calculations within 5%. Temperature rise measured during the first-stage ignition of n-pentane is over-predicted by zero-dimensional kinetic simulations. This work presents, for the first time, highly time-resolved temperature measurements in reactive and non-reactive rapid compression machine experiments. © 2016 Elsevier Ltd.

Time-resolved spectroscopy using a chopper wheel as a fast shutter

International Nuclear Information System (INIS)

Wang, Shicong; Wendt, Amy E.; Boffard, John B.; Lin, Chun C.

2015-01-01

Widely available, small form-factor, fiber-coupled spectrometers typically have a minimum exposure time measured in milliseconds, and thus cannot be used directly for time-resolved measurements at the microsecond level. Spectroscopy at these faster time scales is typically done with an intensified charge coupled device (CCD) system where the image intensifier acts as a “fast” electronic shutter for the slower CCD array. In this paper, we describe simple modifications to a commercially available chopper wheel system to allow it to be used as a “fast” mechanical shutter for gating a fiber-coupled spectrometer to achieve microsecond-scale time-resolved optical measurements of a periodically pulsed light source. With the chopper wheel synchronized to the pulsing of the light source, the time resolution can be set to a small fraction of the pulse period by using a chopper wheel with narrow slots separated by wide spokes. Different methods of synchronizing the chopper wheel and pulsing of the light sources are explored. The capability of the chopper wheel system is illustrated with time-resolved measurements of pulsed plasmas

Development of a method for the in situ measurement of polycyclic aromatic hydrocarbons with time resolved laser fluorescence spectroscopy. Final report

International Nuclear Information System (INIS)

Jaeger, E.; Weissbach, A.; Koenig, F.; Paul, T.

1994-01-01

A method was developed for the detection of polycyclic aromatic hydrocarbons (PAH) in water on the basis of time resolved laser fluorescence spectroscopy. The detection of the sum of PAH in ground- and surfacewater is possible with high sensitivity and selectivity. The fluorescence of other substances like chlorophyll or dissolved organic matter is suppressed by a special choice of spectral and temporal windows. The method works without any sample preparation and gives the results in a very short time. On the basis of this method a first device was built with a sensitivity of 0,1 μg/1 PAH in water. The measuring time was less than one minute. The on site use of this prototype is possible because of the use of a battery driven nitrogen laser together with a notebook computer for system control The application of fiberoptic cables up to 30 meter length makes it possible to use the system for screening and monitoring of polluted areas both in existing wells and without any well by using geological probe techniques. (orig.) [de

Assembly and application of an instrument for attosecond-time-resolved ionization chronoscopy

International Nuclear Information System (INIS)

Uphues, T.

2006-11-01

In the framework of this thesis a new setup for attosecond time-resolved measurements has been built and observations of ionization dynamics in rare gas atoms have been made. This new technique is entitled Ionization Chronoscopy and gives further evidence that time-resolved experiments in the attosecond regime will become a powerful tool for investigations in atomic physics. (orig.)

Biodiesel Production from Residual Palm Oil Contained in Spent Bleaching Earth by In Situ Trans-Esterification

Directory of Open Access Journals (Sweden)

A S Fahmil QRM

2014-06-01

Full Text Available Spent Bleaching Earth (SBE is an industrial solid waste of vegetable oil industry that has a high residual oil to be potentialy converted to biodiesel. This study aims at developing a biodiesel production process technology by utilizing residual palm oil contained in SBE and to test the use of hexane in the trans-esterification process. Optimization process was done by using the Response Surface Method (RSM. The variables studied included catalyst concentration and reaction time. On the other hand, the deoiled SBE resulted from biodiesel production was tested as an adsorbent on biodiesel purification after being reactivated. The method used in the biodiesel production included an in situ acid catalysed esterification followed by in situ base catalysed trans-esterification. The results of RSM showed that the optimum process was obtained at NaOH concentration of 1.8% and reaction time of 104.73 minutes, with a predicted response rate of 97.18% and 95.63% for validation results. The use of hexane could also increase the yield of biodiesel which was obtained on the ratio of hexane to methanol of 0.4:1 (volume of hexane: volume of methanol. On the other hand, the reactivated bleaching earth was effective as an adsorbent in biodiesel production, which was still conform with the Indonesian National Standard.

Time-resolved crystallography using the Hadamard Transform

Science.gov (United States)

Yorke, Briony A.; Beddard, Godfrey S.; Owen, Robin L.; Pearson, Arwen R.

2014-01-01

A new method for performing time-resolved X-ray crystallographic experiments based on the Hadamard Transform is proposed and demonstrated. The time-resolution is defined by the underlying periodicity of the probe pulse sequence and the signal to noise is greatly improved compared to the fastest experiments depending on a single pulse. This approach is general and equally applicable to any spectroscopic or imaging measurement where the probe can be encoded. PMID:25282611

Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite as a potential adsorbent for Cr (VI) removal

CSIR Research Space (South Africa)

Setshedi, KZ

2013-01-01

Full Text Available Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite (PPy OMMT NC), was prepared as a potential adsorbent, via in situ polymerization of pyrrole monomer for adsorption of toxic Cr(VI) from aqueous solution. The WAXD...

In-situ remediation of contaminated ground water using the MAG*SEPSM technology

International Nuclear Information System (INIS)

Dunn, M.J.

1994-01-01

Argonne National Laboratory is leading a project for demonstration of in-situ remediation of contaminated ground water utilizing MAG*SEP SM technology developed by Bradtec. This technology is being considered for eventual application at sites involving groundwater contaminated with heavy metals and/or radionuclides, such as the Savannah River Site (SRS) and Berkeley Pit. The MAG*SEP SM technology uses specially coated magnetic particles to selectively adsorb contaminants from ground water. Particles are mixed with ground water, contaminants are adsorbed onto the particles, and the particles are removed by magnetic filtration. The technology can recover low levels of radioactive and/or inorganic hazardous contamination (in the ppm range), leaving nonradioactive/nonhazardous species essentially unaffected. The first phase of this project has involved the optimization of MAG*SEP SM process chemistry for a selected site at SRS. To date this work has identified a candidate adsorber material (the amino form of iminodicarboxylic acid) for selective removal of lead, cadmium, and mercury from this site's ground water. Decontamination factors of 170, 270, and 235, respective, for each contaminant have been achieved. Further process chemistry optimization work for this adsorber material is planned. The project will eventually lead to an in-situ demonstration of the MAG*SEP SM technology, integrated with the EnviroWall trademark barrier technology developed by Barrier Member Containment Corporation (BMC)

Surface phenomena revealed by in situ imaging: studies from adhesion, wear and cutting

Science.gov (United States)

Viswanathan, Koushik; Mahato, Anirban; Yeung, Ho; Chandrasekar, Srinivasan

2017-03-01

Surface deformation and flow phenomena are ubiquitous in mechanical processes. In this work we present an in situ imaging framework for studying a range of surface mechanical phenomena at high spatial resolution and across a range of time scales. The in situ framework is capable of resolving deformation and flow fields quantitatively in terms of surface displacements, velocities, strains and strain rates. Three case studies are presented demonstrating the power of this framework for studying surface deformation. In the first, the origin of stick-slip motion in adhesive polymer interfaces is investigated, revealing a intimate link between stick-slip and surface wave propagation. Second, the role of flow in mediating formation of surface defects and wear particles in metals is analyzed using a prototypical sliding process. It is shown that conventional post-mortem observation and inference can lead to erroneous conclusions with regard to formation of surface cracks and wear particles. The in situ framework is shown to unambiguously capture delamination wear in sliding. Third, material flow and surface deformation in a typical cutting process is analyzed. It is shown that a long-standing problem in the cutting of annealed metals is resolved by the imaging, with other benefits such as estimation of energy dissipation and power from the flow fields. In closure, guidelines are provided for profitably exploiting in situ observations to study large-strain deformation, flow and friction phenomena at surfaces that display a variety of time-scales.

Sequestration of Antimony on Calcite Observed by Time-Resolved Nanoscale Imaging.

Science.gov (United States)

Renard, François; Putnis, Christine V; Montes-Hernandez, German; King, Helen E; Breedveld, Gijs D; Okkenhaug, Gudny

2018-01-02

Antimony, which has damaging effects on the human body and the ecosystem, can be released into soils, ground-, and surface waters either from ore minerals that weather in near surface environments, or due to anthropogenic releases from waste rich in antimony, a component used in batteries, electronics, ammunitions, plastics, and many other industrial applications. Here, we show that dissolved Sb can interact with calcite, a widespread carbonate mineral, through a coupled dissolution-precipitation mechanism. The process is imaged in situ, at room temperature, at the nanometer scale by using an atomic force microscope equipped with a flow-through cell. Time-resolved imaging allowed following the coupled process of calcite dissolution, nucleation of precipitates at the calcite surface and growth of these precipitates. Sb(V) forms a precipitate, whereas Sb(III) needs to be oxidized to Sb(V) before being incorporated in the new phase. Scanning-electron microscopy and Raman spectroscopy allowed identification of the precipitates as two different calcium-antimony phases (Ca 2 Sb 2 O 7 ). This coupled dissolution-precipitation process that occurs in a boundary layer at the calcite surface can sequester Sb as a solid phase on calcite, which has environmental implications as it may reduce the mobility of this hazardous compound in soils and groundwaters.

A flexible gas flow reaction cell for in situ x-ray absorption spectroscopy studies

Energy Technology Data Exchange (ETDEWEB)

Kroner, Anna B., E-mail: anna.kroner@diamond.ac.uk; Gilbert, Martin; Duller, Graham; Cahill, Leo; Leicester, Peter; Woolliscroft, Richard; Shotton, Elizabeth J. [Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Chilton, Oxfordshire, OX110DE (United Kingdom); Mohammed, Khaled M. H. [UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Chilton, Oxfordshire, OX110FA (United Kingdom); School of Chemistry, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

2016-07-27

A capillary-based sample environment with hot air blower and integrated gas system was developed at Diamond to conduct X-ray absorption spectroscopy (XAS) studies of materials under time-resolved, in situ conditions. The use of a hot air blower, operating in the temperature range of 298-1173 K, allows introduction of other techniques e.g. X-ray diffraction (XRD), Raman spectroscopy for combined techniques studies. The flexibility to use either quartz or Kapton capillaries allows users to perform XAS measurement at energies as low as 5600 eV. To demonstrate performance, time-resolved, in situ XAS results of Rh catalysts during the process of activation (Rh K-edge, Ce L{sub 3}-edge and Cr K-edge) and the study of mixed oxide membrane (La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3−δ}) under various partial oxygen pressure conditions are described.

In Situ Magnetic Separation for Extracellular Protein Production

DEFF Research Database (Denmark)

Kappler, T.; Cerff, Martin; Ottow, Kim Ekelund

2009-01-01

A new approach for in situ product removal from bioreactors is presented in which high-gradient magnetic separation is used. This separation process was used for the adsorptive removal of proteases secreted by Bacillus licheniformis. Small, non-porous bacitracin linked magnetic adsorbents were...... was not influenced by the in situ product removal step. Protease production also remained the same after the separation step. Furthermore, degradation of the protease, which followed first order kinetics, was reduced by using the method. Using a theoretical modeling approach, we Could show that protease yield...... in total was enhanced by using in situ magnetic separation. The process described here is a promising technique to improve overall yield in No production processes which are often limited due to weak downstream operations, Potential limitations encountered during a bioprocess can be overcome...

Optimization and comprehensive characterization of metal hydride based hydrogen storage systems using in-situ Neutron Radiography

Science.gov (United States)

Börries, S.; Metz, O.; Pranzas, P. K.; Bellosta von Colbe, J. M.; Bücherl, T.; Dornheim, M.; Klassen, T.; Schreyer, A.

2016-10-01

For the storage of hydrogen, complex metal hydrides are considered as highly promising with respect to capacity, reversibility and safety. The optimization of corresponding storage tanks demands a precise and time-resolved investigation of the hydrogen distribution in scaled-up metal hydride beds. In this study it is shown that in situ fission Neutron Radiography provides unique insights into the spatial distribution of hydrogen even for scaled-up compacts and therewith enables a direct study of hydrogen storage tanks. A technique is introduced for the precise quantification of both time-resolved data and a priori material distribution, allowing inter alia for an optimization of compacts manufacturing process. For the first time, several macroscopic fields are combined which elucidates the great potential of Neutron Imaging for investigations of metal hydrides by going further than solely 'imaging' the system: A combination of in-situ Neutron Radiography, IR-Thermography and thermodynamic quantities can reveal the interdependency of different driving forces for a scaled-up sodium alanate pellet by means of a multi-correlation analysis. A decisive and time-resolved, complex influence of material packing density is derived. The results of this study enable a variety of new investigation possibilities that provide essential information on the optimization of future hydrogen storage tanks.

High efficient removal of chromium (VI) using glycine doped polypyrrole adsorbent from aqueous solution

CSIR Research Space (South Africa)

Ballav, N

2012-08-01

Full Text Available Glycine doped polypyrrole (PPy-gly) adsorbent was prepared via in situ polymerization of pyrrole (Py) monomer in the presence of glycine (gly) for the removal of Cr(VI). Formation of PPy homopolymer and inclusion of gly in the PPy matrix were...

Time-resolved suprathermal x-rays

International Nuclear Information System (INIS)

Lee, P.H.Y.; Rosen, M.D.

1978-01-01

Temporally resolved x-ray spectra in the range of 1 to 20 keV have been obtained from gold disk targets irradiated by 1.06 μm laser pulses from the Argus facility. The x-ray streak camera used for the measurement has been calibrated for streak speed and dynamic range by using an air-gap Fabry-Perot etalon, and the instrument response has been calibrated using a multi-range monoenergetic x-ray source. The experimental results indicate that we are able to observe the ''hot'' x-ray temperature evolve in time and that the experimentally observed values can be qualitatively predicted by LASNEX code computations when the inhibited transport model is used

Time-resolved spectroscopy of laser-induced breakdown in water

Science.gov (United States)

Thomas, Robert J.; Hammer, Daniel X.; Noojin, Gary D.; Stolarski, David J.; Rockwell, Benjamin A.; Roach, William P.

1996-05-01

Laser pulses of 60-ps and 80-ps at a wavelength of 532-nm and 1064-nm respectively were used to produce laser induced breakdown in triple-distilled water. The resulting luminescent flash from the plasma was captured with an imaging spectrograph coupled to a streak camera with a 5-ps time resolution. The wavelength range was 350 to 900-nm. We present the resulting experimental data which gives plasma duration and time-resolved spectral information. Plasma temperature is also computed from the data. All parameters are presented at a pulse energy of 1-mJ and are compared with time-integrated spectra at the same pulse duration and at 5 to 7-ns pulse duration in a similar energy range.

Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources.

Science.gov (United States)

Rutherford, Michael E; Chapman, David J; White, Thomas G; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E

2016-05-01

The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

Femtosecond Time-Resolved Resonance-Enhanced CARS of Gaseous Iodine at Room Temperature

International Nuclear Information System (INIS)

He Ping; Fan Rong-Wei; Xia Yuan-Qin; Yu Xin; Chen De-Ying; Yao Yong

2011-01-01

Time-resolved resonance-enhanced coherent anti-Stokes Raman scattering (CARS) is applied to investigate molecular dynamics in gaseous iodine. 40 fs laser pulses are applied to create and monitor the high vibrational states of iodine at room temperature (corresponding to a vapor pressure as low as about 35 Pa) by femtosecond time-resolved CARS. Depending on the time delay between the probe pulse and the pump/Stokes pulse pairs, the high vibrational states both on the electronically ground states and the excited states can be detected as oscillations in the CARS transient signal. It is proved that the femtosecond time-resolved CARS technique is a promising candidate for investigating the molecular dynamics of a low concentration system and can be applied to environmental and atmospheric monitoring measurements. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Orientational epitaxy in adsorbed monolayers

International Nuclear Information System (INIS)

Novaco, A.D.; McTague, J.P.

1977-01-01

The ground state for adsorbed monolayers on crystalline substrates is shown to involve a definite relative orientation of the substrate and adsorbate crystal axes, even when the relative lattice parameters are incommensurate. The rotation angle which defines the structure of the monolayer-substrate system is determined by the competition between adsorbate-substrate and adsorbate-adsorbate energy terms, and is generally not a symmetry angle. Numerical predictions are presented for the rare gas-graphite systems, whose interaction potentials are rather well known. Recent LEED data for some of these systems appear to corroborate these predictions

Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

International Nuclear Information System (INIS)

Hedqvist, A.; Rachlew-Kaellne, E.

1998-01-01

Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and Z eff together with a description of the interpretation and the equipment are presented. (author)

The influence of the electronic structure of adsorbate-substrate complexes on photoisomerization ability

International Nuclear Information System (INIS)

Bronner, Christopher; Schulze, Michael; Hagen, Sebastian; Tegeder, Petra

2012-01-01

We use time-resolved two-photon photoemission to study two molecular photoswitches at the Au(111) surface, namely azobenzene and its derivative tetra-tert-butyl-azobenzene (TBA). Electronic states located at the substrate-adsorbate interface are found to be a sensitive probe for the photoisomerization of TBA. In contrast to TBA, azobenzene loses its switching ability at the Au(111) surface. Besides the different adsorption geometries of both molecules, we partly attribute the quenching in the case of azobenzene to a shift of the highest occupied molecular orbital (HOMO) with respect to the gold d-bands, which renders the hole transfer involved in the photoisomerization mechanism of TBA inefficient. (paper)

Modeling adsorption: Investigating adsorbate and adsorbent properties

Science.gov (United States)

Webster, Charles Edwin

1999-12-01

Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

Ecological applications of the irradiated adsorbents

International Nuclear Information System (INIS)

Tusseyev, T.

2004-01-01

Full text: In our previous works it was shown that after irradiation some adsorbents gain new interesting properties such as increasing (or decreasing) of their adsorption capacity, selectivity in relation to some gases, change of chemical bounds of gas molecules with adsorbent surface as well as other properties. We investigated a lot of adsorbents with semiconducting and dielectric properties. A high temperature superconductor was investigated also. Adsorbents were irradiated by ultraviolet (UV) and gamma - radiation, reactor (n.γ) - radiation, α-particles (E=40-50 MeV), protons ( E=30 MeV), and also He-3 ions (E-29-60 MeV). The following techniques were used: volumetric (manometrical), mass-spectrometer and IR spectroscopic methods, and also method of electronic - paramagnetic resonance (spin paramagnetic resonance) The obtained results allow to speak about creation of new adsorbents for gas purification (clearing) from harmful impurities, gas selection into components, an increasing of adsorbing surface. Thus one more advantage of the irradiated adsorbents is that they have 'memory effect', i.e. they can be used enough long time after irradiation. In laboratory conditions we built the small-sized adsorptive pump on the basis of the irradiated zeolites which are capable to work in autonomous conditions. It was found, that some of adsorbents after irradiation gain (or lose) selectivity in relation to definite gases. So, silica gel, which one in initial state does not adsorb hydrogen, after gamma irradiation it becomes active in relation to hydrogen. Some of rare earths oxides also show selectivity in relation to hydrogen and oxygen depending on a type of irradiation. Thus, it is possible to create different absorbents, depending on a solved problem, using a way or selection of adsorbents, either of radiation type and energy, as a result obtained adsorbents can be used for various ecological purposes

Time-resolved imaging of purely valence-electron dynamics during a chemical reaction

DEFF Research Database (Denmark)

Hockett, Paul; Bisgaard, Christer Z.; Clarkin, Owen J.

2011-01-01

Chemical reactions are manifestations of the dynamics of molecular valence electrons and their couplings to atomic motions. Emerging methods in attosecond science can probe purely electronic dynamics in atomic and molecular systems(1-6). By contrast, time-resolved structural-dynamics methods...... such as electron(7-10) or X-ray diffraction(11) and X-ray absorption(12) yield complementary information about the atomic motions. Time-resolved methods that are directly sensitive to both valence-electron dynamics and atomic motions include photoelectron spectroscopy(13-15) and high-harmonic generation(16......,17): in both cases, this sensitivity derives from the ionization-matrix element(18,19). Here we demonstrate a time-resolved molecular-frame photoelectron-angular-distribution (TRMFPAD) method for imaging the purely valence-electron dynamics during a chemical reaction. Specifically, the TRMFPADs measured during...

Time-resolved x-ray diagnostics

International Nuclear Information System (INIS)

Lyons, P.B.

1981-01-01

Techniques for time-resolved x-ray diagnostics will be reviewed with emphasis on systems utilizing x-ray diodes or scintillators. System design concerns for high-bandwidth (> 1 GHz) diagnostics will be emphasized. The limitations of a coaxial cable system and a technique for equalizing to improve bandwidth of such a system will be reviewed. Characteristics of new multi-GHz amplifiers will be presented. An example of a complete operational system on the Los Alamos Helios laser will be presented which has a bandwidth near 3 GHz over 38 m of coax. The system includes the cable, an amplifier, an oscilloscope, and a digital camera readout

Time and energy resolved runaway measurements in TFR from induced radioactivity

International Nuclear Information System (INIS)

1983-09-01

A time and energy resolved measurement of the radioactivity induced by runaway electrons in proper samples has been developped in TFR. The data give an information on the confinement time of these electrons, which appears to be strongly dependent on the toroidal field, suggesting the onset of a magnetic turbulence at lower fields. Observations showing that the runaway electrons deeply penetrate into the limiter shadow are also reported

A novel multiplex absorption spectrometer for time-resolved studies

Science.gov (United States)

Lewis, Thomas; Heard, Dwayne E.; Blitz, Mark A.

2018-02-01

A Time-Resolved Ultraviolet/Visible (UV/Vis) Absorption Spectrometer (TRUVAS) has been developed that can simultaneously monitor absorption at all wavelengths between 200 and 800 nm with millisecond time resolution. A pulsed photolysis laser (KrF 248 nm) is used to initiate chemical reactions that create the target species. The absorption signals from these species evolve as the composition of the gas in the photolysis region changes over time. The instrument can operate at pressures over the range ˜10-800 Torr and can measure time-resolved absorbances systems (in particular the Herriott cell), there are fundamental differences, most notably the ability to adjust each mirror to maximise the overlap between the probe beam and the photolysis laser. Another feature which aids the sensitivity and versatility of the system is the use of 2 high-throughput spectrographs coupled with sensitive line-array CCDs, which can measure absorbance from ˜200 to 800 nm simultaneously. The capability of the instrument is demonstrated via measurements of the absorption spectrum of the peroxy radical, HOCH2CH2O2, and its self-reaction kinetics.

Poly(acrylic acid) modifying bentonite with in-situ polymerization for removing lead ions.

Science.gov (United States)

He, Y F; Zhang, L; Yan, D Z; Liu, S L; Wang, H; Li, H R; Wang, R M

2012-01-01

In this paper, a new kind of poly(acrylic acid) modified clay adsorbent, the poly(acrylic acid)/bentonite composite (PAA/HB) was prepared by in-situ polymerization, and utilized to remove lead(II) ions from solutions. The maximum adsorption of adsorbent is at pH 5 for metal ions, whereas the adsorption starts at pH 2. The effects of contact time (5-60 min), initial concentration of metal ions (200-1,000 mg/L) and adsorbent dosage (0.04-0.12 g/100 mL) have been reported in this article. The experimental data were investigated by means of kinetic and equilibrium adsorption isotherms. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order equation. The experimental data fitted the pseudo-second-order kinetic model very well. Langmuir and Freundlich isotherms were tried for the system to better understand the adsorption isotherm process. The maximal adsorption capacity of the lead(II) ions on the PAA/HB, as calculated from the Langmuir model, was 769.2 mg/g. The results in this study indicated that PAA/HB was an attractive candidate for removing lead(II) (99%).

Lucas–Kanade fluid trajectories for time-resolved PIV

International Nuclear Information System (INIS)

Yegavian, Robin; Leclaire, Benjamin; Illoul, Cédric; Losfeld, Gilles; Champagnat, Frédéric

2016-01-01

We introduce a new method for estimating fluid trajectories in time-resolved PIV. It relies on a Lucas–Kanade paradigm and consists in a simple and direct extension of a two-frame estimation with FOLKI-PIV (Champagnat et al 2011 Exp. Fluids 50 1169–82). The so-called Lucas–Kanade Fluid Trajectories (LKFT) are assumed to be polynomial in time, and are found as the minimizer of a global functional, in which displacements are sought so as to match the intensities of a series of images pairs in the sequence, in the least-squares sense. All pairs involve the central image, similar to other recent time-resolved approaches (FTC (Lynch and Scarano 2013 Meas. Sci. Technol . 24 035305) and FTEE (Jeon et al 2014 Exp. Fluids 55 1–16)). As switching from a two-frame to a time-resolved objective simply amounts to adding terms in a functional, no significant additional algorithmic element is required. Similar to FOLKI-PIV the method is very well suited for GPU acceleration, which is an important feature as computational complexity increases with the image sequence size. Tests on synthetic data exhibiting peak-locking show that increasing the image sequence size strongly reduces both associated bias and random error, and that LKFT has a remaining total error comparable to that of FTEE on this case. Results on case B of the third PIV challenge (Stanislas et al 2008 Exp. Fluids 45 27–71) also show its ability to drastically reduce the error in situations with low signal-to-noise ratio. These results are finally confirmed on experimental images acquired in the near-field of a low Reynolds number jet. Strong reductions in peak-locking, spatial and temporal noise compared to two-frame estimation are also observed, on the displacement components themselves, as well as on spatial or temporal derivatives, such as vorticity and material acceleration. (paper)

Time-resolved spectral measurements above 80 A

International Nuclear Information System (INIS)

Kauffman, R.L.; Ceglio, N.; Medecki, H.

1983-01-01

We have made time-resolved spectral measurements above 80 A from laser-produced plasmas. These are made using a transmission grating spectrograph whose primary components are a cylindrically-curved x-ray mirror for light collection, a transmission grating for spectral dispersions, and an x-ray streak camera for temporal resolution. A description of the instrument and an example of the data are given

Krypton retention on solid adsorbents

International Nuclear Information System (INIS)

Monson, P.R. Jr.

1982-01-01

An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-40 0 to -80 0 C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite

An in situ XPS study of L-cysteine co-adsorbed with water on polycrystalline copper and gold

Science.gov (United States)

Jürgensen, Astrid; Raschke, Hannes; Esser, Norbert; Hergenröder, Roland

2018-03-01

The interactions of biomolecules with metal surfaces are important because an adsorbed layer of such molecules introduces complex reactive functionality to the substrate. However, studying these interactions is challenging: they usually take place in an aqueous environment, and the structure of the first few monolayers on the surface is of particular interest, as these layers determine most interfacial properties. Ideally, this requires surface sensitive analysis methods that are operated under ambient conditions, for example ambient pressure x-ray photoelectron spectroscopy (AP-XPS). This paper focuses on an AP-XPS study of the interaction of water vapour and l-Cysteine on polycrystalline copper and gold surfaces. Thin films of l-Cysteine were characterized with XPS in UHV and in a water vapour atmosphere (P ≤ 1 mbar): the structure of the adsorbed l-Cysteine layer depended on substrate material and deposition method, and exposure of the surface to water vapour led to the formation of hydrogen bonds between H2O molecules and the COO- and NH2 groups of adsorbed l-Cysteine zwitterions and neutral molecules, respectively. This study also proved that it is possible to investigate monolayers of biomolecules in a gas atmosphere with AP-XPS using a conventional laboratory Al-Kα x-ray source.

Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

Science.gov (United States)

Hedqvist, Anders; Rachlew-Källne, Elisabeth

1998-09-01

Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and 0741-3335/40/9/004/img1 together with a description of the interpretation and the equipment are presented.

Characterization of as-grown and adsorbate-covered N-polar InN surfaces using in situ photoelectron spectroscopy

International Nuclear Information System (INIS)

Eisenhardt, Anja; Himmerlich, Marcel; Krischok, Stefan

2012-01-01

The surface electronic properties and adsorption behaviour of as-grown and oxidized N-polar InN films are characterized by photoelectron spectroscopy (XPS, UPS). The epitaxial growth of the InN layers was performed by plasma-assisted molecular beam epitaxy on GaN/6H-SiC(000-1). After growth and in situ characterization the InN surfaces were exposed to molecular oxygen to evaluate the adsorption behaviour of O 2 on N-polar InN and to study its impact on the surface electronic properties of the III-nitride material. The results are compared with studies on In-polar InN on GaN/sapphire templates. The as-grown N-polar InN surface exhibits a pronounced surface state at a binding energy of ∝1.6 eV. The valence band minimum lies about 0.8-1.0 eV below the surface Fermi level. Additionally, the XPS core level binding energies for InN(000-1) are reduced compared to InN(0001) films, indicating different surface band bending for clean N-polar and In-polar InN, respectively. The interaction of molecular oxygen with the InN(000-1) surface leads to a downward band bending by 0.1 eV compared to the initial state. Additional adsorption of species from the residual gas of the UHV chamber increases the surface downward band bending. Furthermore two pronounced oxygen related states with an energy distance of ∝5 eV could be detected in the valence band region. The adsorbed oxygen results in an additional component in the N1s core level spectra, which is interpreted as formation of NO x bonds. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Moment analysis of the time-dependent transmission of a step-function input of a radioactive gas through an adsorber bed

International Nuclear Information System (INIS)

Lee, T.V.; Rothstein, D.; Madey, R.

1986-01-01

The time-dependent concentration of a radioactive gas at the outlet of an adsorber bed for a step change in the input concentration is analyzed by the method of moments. This moment analysis yields analytical expressions for calculating the kinetic parameters of a gas adsorbed on a porous solid in terms of observables from a time-dependent transmission curve. Transmission is the ratio of the adsorbate outlet concentration to that at the inlet. The three nonequilibrium parameters are the longitudinal diffusion coefficient, the solid-phase diffusion coefficient, and the interfacial mass-transfer coefficient. Three quantities that can be extracted in principle from an experimental transmission curve are the equilibrium transmission, the average residence (or propagation) time, and the first-moment relative to the propagation time. The propagation time for a radioactive gas is given by the time integral of one minus the transmission (expressed as a fraction of the steady-state transmission). The steady-state transmission, the propagation time, and the first-order moment are functions of the three kinetic parameters and the equilibrium adsorption capacity. The equilibrium adsorption capacity is extracted from an experimental transmission curve for a stable gaseous isotope. The three kinetic parameters can be obtained by solving the three analytical expressions simultaneously. No empirical correlations are required

Life-time resolved emission spectra in CdI2 crystals

International Nuclear Information System (INIS)

Kawabata, Seiji; Nakagawa, Hideyuki

2007-01-01

The emission spectrum of CdI 2 is composed of ultraviolet (UV), green (G) and yellow (Y and Y') bands peaking at 3.38, 2.50, 2.16 and 2.25 eV, respectively. In order to determine the initial states of the Y- and G-luminescence, decay curves have been measured at 6 and 80 K by varying emission energy. The observed decay curves are composed of two or three exponential components. These decay components were named τ 1 , τ 2 , τ 3 , τ 3' and τ 4 . The emission spectrum for each decay component, i.e., the life-time resolved emission spectrum, was constructed from the observed decay curves. At 6 K, three bands at 2.12, 2.49 and 2.64 eV are obtained for τ 1 , τ 2 and τ 3 components, respectively. At 80 K, a dominant band for the τ 4 component and a weak band for the τ 3' component appear on the same energy position at 2.25 eV. The origin of each emission band in the life-time resolved emission spectra will be briefly discussed

Positronium chemistry in porous adsorbents

International Nuclear Information System (INIS)

Foti, G.; Nagy, L.G.; Moravcsik, G.; Schay, G.

1981-01-01

Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22 Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

Development of soft x-ray time-resolved photoemission spectroscopy system with a two-dimensional angle-resolved time-of-flight analyzer at SPring-8 BL07LSU

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Manami; Yamamoto, Susumu; Nakamura, Fumitaka; Yukawa, Ryu; Fukushima, Akiko; Harasawa, Ayumi; Kakizaki, Akito; Matsuda, Iwao [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Chiba 277-8581 (Japan); Kousa, Yuka; Kondoh, Hiroshi [Department of Chemistry, Keio University, Yokohama 223-8522 (Japan); Tanaka, Yoshihito [RIKEN/SPring-8 Center, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2012-02-15

We have developed a soft x-ray time-resolved photoemission spectroscopy system using synchrotron radiation (SR) at SPring-8 BL07LSU and an ultrashort pulse laser system. Two-dimensional angle-resolved measurements were performed with a time-of-flight-type analyzer. The photoemission spectroscopy system is synchronized to light pulses of SR and laser using a time control unit. The performance of the instrument is demonstrated by mapping the band structure of a Si(111) crystal over the surface Brillouin zones and observing relaxation of the surface photo-voltage effect using the pump (laser) and probe (SR) method.

Time-resolved laser-induced fluorescence in the nuclear fuel cycle

International Nuclear Information System (INIS)

Moulin, C.; Decambox, P.; Mauchien, P.; Petit, A.

1995-01-01

Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented. (author)

Time-resolved magnetic field effects in exciplex systems under X-irradiation

International Nuclear Information System (INIS)

Anishchik, S.V.; Lavrik, N.L.

1988-01-01

The presence of exciplex systems after X-irradiation of pyrene and N,N-diethylaniline in methanol as well as the influence of the applied magnetic field on exciplex fluorescence was registered using a time-resolving method. The experimental results confirmed the hypothesis on exciplex emergence in the system under study. (author)

Time resolved resonant inelastic X-ray scattering: A supreme tool to understand dynamics in solids and molecules

International Nuclear Information System (INIS)

Beye, M.; Wernet, Ph.; Schüßler-Langeheine, C.; Föhlisch, A.

2013-01-01

Highlights: •The high specificity of RIXS ideally suits time-resolved measurements. •Methods relating to the core hole lifetime cover the low femtosecond regime. •Pump-probe methods are used starting at sub-ps time scales. •FELs and synchrotrons are useful for pump-probe studies. •Examples from solid state dynamics and molecules are discussed. -- Abstract: Dynamics in materials typically involve different degrees of freedom, like charge, lattice, orbital and spin in a complex interplay. Time-resolved resonant inelastic X-ray scattering (RIXS) as a highly selective tool can provide unique insight and follow the details of dynamical processes while resolving symmetries, chemical and charge states, momenta, spin configurations, etc. In this paper, we review examples where the intrinsic scattering duration time is used to study femtosecond phenomena. Free-electron lasers access timescales starting in the sub-ps range through pump-probe methods and synchrotrons study the time scales longer than tens of ps. In these examples, time-resolved resonant inelastic X-ray scattering is applied to solids as well as molecular systems

Technical note: Time-resolved immunofluorometric assay for growth hormone in ruminants

DEFF Research Database (Denmark)

Løvendahl, P.; Adamsen, J.; Lund, Regina Teresa

2003-01-01

for 4 h at 25degreesC. Plates were then washed six times, incubated for 5 to 10 min with 250 muL of enhancement solution, and fluorescence read with a time-resolved fluorometer. The sensitivity of the assay was 0.1 ng/mL, and the working range was 0.2 to 200 ng/mL. Recovery of quantitative amounts...

Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

DEFF Research Database (Denmark)

Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank

2016-01-01

Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IR....... The equations are applied to experimental TR-IRSL data of natural feldspars, and good agreement is found between experimental and modeling results....

Time-resolved fluorescence analysis of the mobile flavin cofactor

Indian Academy of Sciences (India)

Conformational heterogeneity of the FAD cofactor in -hydroxybenzoate hydroxylase (PHBH) was investigated with time-resolved polarized flavin fluorescence. For binary enzyme/substrate (analogue) complexes of wild-type PHBH and Tyr222 mutants, crystallographic studies have revealed two distinct flavin conformations ...

Detecting aromatic compounds on planetary surfaces using ultraviolet time-resolved fluorescence spectroscopy

Science.gov (United States)

Eshelman, E.; Daly, M. G.; Slater, G.; Cloutis, E.

2018-02-01

Many aromatic organic molecules exhibit strong and characteristic fluorescence when excited with ultraviolet radiation. As laser excitation in the ultraviolet generates both fluorescence and resonantly enhanced Raman scattering of aromatic vibrational modes, combined Raman and fluorescence instruments have been proposed to search for organic compounds on Mars. In this work the time-resolved fluorescence of a suite of 24 compounds composed of 2-5 ringed alternant, non-alternant, and heterocyclic PAHs was measured. Fluorescence instrumentation with similar specifications to a putative flight instrument was capable of observing the fluorescence decay of these compounds with a sub-ns resolution. Incorporating time-resolved capabilities was also found to increase the ability to discriminate between individual PAHs. Incorporating time-resolved fluorescence capabilities into an ultraviolet gated Raman system intended for a rover or lander can increase the ability to detect and characterize PAHs on planetary surfaces.

Mobile Charge Generation Dynamics in P3HT:PCBM Observed by Time-Resolved Terahertz Spectroscopy

DEFF Research Database (Denmark)

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

2012-01-01

Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

Mobile charge generation dynamics in P3HT: PCBM observed by time-resolved terahertz spectroscopy

DEFF Research Database (Denmark)

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

2012-01-01

Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

Time and spectrum-resolving multiphoton correlator for 300–900 nm

Energy Technology Data Exchange (ETDEWEB)

Johnsen, Kelsey D.; Thibault, Marilyne; Jennewein, Thomas [Institute for Quantum Computing and Department for Physics and Astronomy, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L 3G1 (Canada); Kolenderski, Piotr, E-mail: kolenderski@fizyka.umk.pl [Institute for Quantum Computing and Department for Physics and Astronomy, University of Waterloo, 200 University Ave. West, Waterloo, Ontario N2L 3G1 (Canada); Faculty of Physics, Astronomy and Informatics, Institute of Physics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Scarcella, Carmelo; Tosi, Alberto [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy)

2014-10-14

We demonstrate a single-photon sensitive spectrometer in the visible range, which allows us to perform time-resolved and multi-photon spectral correlation measurements at room temperature. It is based on a monochromator composed of two gratings, collimation optics, and an array of single photon avalanche diodes. The time resolution can reach 110 ps and the spectral resolution is 2 nm/pixel, limited by the design of the monochromator. This technique can easily be combined with commercial monochromators and can be useful for joint spectrum measurements of two photons emitted in the process of parametric down conversion, as well as time-resolved spectrum measurements in optical coherence tomography or medical physics applications.

Mechanism of Particle Formation in Silver/Epoxy Nanocomposites Obtained through a Visible-Light-Assisted in Situ Synthesis.

Science.gov (United States)

dell'Erba, Ignacio E; Martínez, Francisco D; Hoppe, Cristina E; Eliçabe, Guillermo E; Ceolín, Marcelo; Zucchi, Ileana A; Schroeder, Walter F

2017-10-03

A detailed understanding of the processes taking place during the in situ synthesis of metal/polymer nanocomposites is crucial to manipulate the shape and size of nanoparticles (NPs) with a high level of control. In this paper, we report an in-depth time-resolved analysis of the particle formation process in silver/epoxy nanocomposites obtained through a visible-light-assisted in situ synthesis. The selected epoxy monomer was based on diglycidyl ether of bisphenol A, which undergoes relatively slow cationic ring-opening polymerization. This feature allowed us to access a full description of the formation process of silver NPs before this was arrested by the curing of the epoxy matrix. In situ time-resolved small-angle X-ray scattering investigation was carried out to follow the evolution of the number and size of the silver NPs as a function of irradiation time, whereas rheological experiments combined with near-infrared and ultraviolet-visible spectroscopies were performed to interpret how changes in the rheological properties of the matrix affect the nucleation and growth of particles. The analysis of the obtained results allowed us to propose consistent mechanisms for the formation of metal/polymer nanocomposites obtained by light-assisted one-pot synthesis. Finally, the effect of a thermal postcuring treatment of the epoxy matrix on the particle size in the nanocomposite was investigated.

Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

Science.gov (United States)

Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

2015-02-01

We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

Time-resolved x-ray line diagnostics of laser-produced plasmas

International Nuclear Information System (INIS)

Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D.; Lee, R.W.

1982-11-01

We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 μm light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers, whose Z's range from 13 to 22, are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasms is changed from SiO 2 to PbO or In. Spectra will be presented along with preliminary analysis of the data

Time-resolved x-ray line diagnostics of laser-produced plasmas

International Nuclear Information System (INIS)

Kauffman, R.L.; Matthews, D.L.; Kilkenny, J.D.; Lee, R.W.

1982-01-01

We have examined the underdense plasma conditions of laser irradiated disks using K x-rays from highly ionized ions. A 900 ps laser pulse of 0.532 μm light is used to irradiate various Z disks which have been doped with low concentrations of tracer materials. The tracers whose Z's range from 13 to 22 are chosen so that their K x-ray spectrum is sensitive to typical underdense plasma temperatures and densities. Spectra are measured using a time-resolved crystal spectrograph recording the time history of the x-ray spectrum. A spatially-resolved, time-integrated crystal spectrograph also monitors the x-ray lines. Large differences in Al spectra are observed when the host plasma is changed from SiO 2 to PbO or In. Spectra will be presented along with preliminary analysis of the data

Time-resolved explosion of intense-laser-heated clusters.

Science.gov (United States)

Kim, K Y; Alexeev, I; Parra, E; Milchberg, H M

2003-01-17

We investigate the femtosecond explosive dynamics of intense laser-heated argon clusters by measuring the cluster complex transient polarizability. The time evolution of the polarizability is characteristic of competition in the optical response between supercritical and subcritical density regions of the expanding cluster. The results are consistent with time-resolved Rayleigh scattering measurements, and bear out the predictions of a recent laser-cluster interaction model [H. M. Milchberg, S. J. McNaught, and E. Parra, Phys. Rev. E 64, 056402 (2001)

Time-resolved explosion of intense-laser-heated clusters

International Nuclear Information System (INIS)

Kim, K.Y.; Alexeev, I.; Parra, E.; Milchberg, H.M.

2003-01-01

We investigate the femtosecond explosive dynamics of intense laser-heated argon clusters by measuring the cluster complex transient polarizability. The time evolution of the polarizability is characteristic of competition in the optical response between supercritical and subcritical density regions of the expanding cluster. The results are consistent with time-resolved Rayleigh scattering measurements, and bear out the predictions of a recent laser-cluster interaction model [H. M. Milchberg, S. J. McNaught, and E. Parra, Phys. Rev. E 64, 056402 (2001)

Time-resolved PHERMEX image restorations constrained with an additional multiply-exposed image

International Nuclear Information System (INIS)

Kruger, R.P.; Breedlove, J.R. Jr.; Trussell, H.J.

1978-06-01

There are a number of possible industrial and scientific applications of nanosecond cineradiographs. Although the technology exists to produce closely spaced pulses of x rays for this application, the quality of the time-resolved radiographs is severely limited. The limitations arise from the necessity of using a fluorescent screen to convert the transmitted x rays to light and then using electro-optical imaging systems to gate and to record the images with conventional high-speed cameras. It has been proposed that, in addition to the time-resolved images, a conventional multiply exposed radiograph be obtained. This report uses both PHERMEX and conventional photographic simulations to demonstrate that the additional information supplied by the multiply exposed radiograph can be used to improve the quality of digital image restorations of the time-resolved pictures over what could be achieved with the degraded images alone

In situ Ru K-edge EXAFS of CO adsorption on a Ru modified Pt/C fuel cell catalyst

International Nuclear Information System (INIS)

Rose, Abigail; Bilsborrow, Robert; King, Colin R.; Ravikumar, M.K.; Qian Yangdong; Wiltshire, Richard J.K.; Crabb, Eleanor M.; Russell, Andrea E.

2009-01-01

The Ru-CO bond of CO adsorbed on a Ru modified Pt/C fuel cell catalyst has been directly probed by in situ EXAFS at the Ru K-edge, providing evidence of a CO:metal surface atom ratio greater than 1:1 and that CO is adsorbed at bridging sites associated with Ru atoms at the surface of the catalyst nanoparticles. This result illustrates the limitations of single crystal models as representations of the bonding of adsorbed species at nanoparticle surfaces.

Dynamic Time-Resolved Chirped-Pulse Rotational Spectroscopy of Vinyl Cyanide Photoproducts in a Room Temperature Flow Reactor

Science.gov (United States)

Zaleski, Daniel P.; Prozument, Kirill

2017-06-01

Chirped-pulsed (CP) Fourier transform rotational spectroscopy invented by Brooks Pate and coworkers a decade ago is an attractive tool for gas phase chemical dynamics and kinetics studies. A good reactor for such a purpose would have well-defined (and variable) temperature and pressure conditions to be amenable to accurate kinetic modeling. Furthermore, in low pressure samples with large enough number of molecular emitters, reaction dynamics can be observable directly, rather than mediated by supersonic expansion. In the present work, we are evaluating feasibility of in situ time-resolved CP spectroscopy in a room temperature flow tube reactor. Vinyl cyanide (CH_2CHCN), neat or mixed with inert gasses, flows through the reactor at pressures 1-50 μbar (0.76-38 mTorr) where it is photodissociated by a 193 nm laser. Millimeter-wave beam of the CP spectrometer co-propagates with the laser beam along the reactor tube and interacts with nascent photoproducts. Rotational transitions of HCN, HNC, and HCCCN are detected, with ≥10 μs time-steps for 500 ms following photolysis of CH_2CHCN. The post-photolysis evolution of the photoproducts' rotational line intensities is investigated for the effects of rotational and vibrational thermalization of energized photoproducts. Possible contributions from bimolecular and wall-mediated chemistry are evaluated as well.

Femtosecond time-resolved transient absorption spectroscopy of xanthophylls.

Science.gov (United States)

Niedzwiedzki, Dariusz M; Sullivan, James O; Polívka, Tomás; Birge, Robert R; Frank, Harry A

2006-11-16

Xanthophylls are a major class of photosynthetic pigments that participate in an adaptation mechanism by which higher plants protect themselves from high light stress. In the present work, an ultrafast time-resolved spectroscopic investigation of all the major xanthophyll pigments from spinach has been performed. The molecules are zeaxanthin, lutein, violaxanthin, and neoxanthin. beta-Carotene was also studied. The experimental data reveal the inherent spectral properties and ultrafast dynamics including the S(1) state lifetimes of each of the pigments. In conjunction with quantum mechanical computations the results address the molecular features of xanthophylls that control the formation and decay of the S* state in solution. The findings provide compelling evidence that S* is an excited state with a conformational geometry twisted relative to the ground state. The data indicate that S* is formed via a branched pathway from higher excited singlet states and that its yield depends critically on the presence of beta-ionylidene rings in the polyene system of pi-electron conjugated double bonds. The data are expected to be beneficial to researchers employing ultrafast time-resolved spectroscopic methods to investigate the mechanisms of both energy transfer and nonphotochemical quenching in higher plant preparations.

Time resolved spectroscopy of GRB 030501 using INTEGRAL

DEFF Research Database (Denmark)

Beckmann, V.; Borkowski, J.; Courvoisier, T.J.L.

2003-01-01

The gamma-ray instruments on-board INTEGRAL offer an unique opportunity to perform time resolved analysis on GRBs. The imager IBIS allows accurate positioning of GRBs and broad band spectral analysis, while SPI provides high resolution spectroscopy. GRB 030501 was discovered by the INTEGRAL Burst...... the Ulysses and RHESSI experiments....

Time-resolved luminescence from feldspars: New insight into fading

DEFF Research Database (Denmark)

Tsukamoto, S.; Denby, P.M.; Murray, A.S.

2006-01-01

Time-resolved infrared optically stimulated luminescence (IR-OSL) signals of K- and Na-feldspar samples extracted from sediments were measured in UV, blue and red detection windows, using a fast photon counter and pulsed IR stimulation (lambda = 875 nm). We observe that the relative contribution ...

New layout of time resolved beam energy spectrum measurement for dragon-I

International Nuclear Information System (INIS)

Liao Shuqing; Zhang Kaizhi; Shi Jinshui

2010-01-01

A new layout of time resolved beam energy spectrum measurement is proposed for Dragon-I by a new method named RBS (rotating beams in solenoids). The basic theory of RBS and the new layout are presented and the measuring error is also discussed. The derived time resolved beam energy spectrum is discrete and is determined by measuring the beam's rotating angle and expanding width through a group of solenoids at the export of Dragon-I. (authors)

Time-resolved Laue diffraction from protein crystals: Instrumental considerations

International Nuclear Information System (INIS)

Bilderback, D.H.; Cornell Univ., Ithaca, NY; Moffat, K.; Szebenyi, D.M.E.

1984-01-01

A serious limitation of macromolecular crystallography has been its inability to determine changes in structure on a biochemical time scale of milliseconds or less. Recently, we have shown that X-ray exposures on single crystals of macromolecules may be obtained in the millisecond time range through the use of intense, polychromatic radiation with Δlambda/lambda approx.= 0.2 derived from the Cornell High Energy Synchrotron Source, CHESS. Such radiation falling on a stationary crystal yields a Laue diffraction pattern, in which almost all Laue reflections arise from a unique set of Miller indices and where their intensities are automatically integrated over wavelength. This Laue technique requires wide band pass optics, which may be obtained by a combination of reflection and transmission mirrors, filters or layered synthetic microstructures. Time-resolved macromolecular crystallography may be achieved by several data collection schemes: 'one-shot' recording coupled to a simple streak camera, repetitive sample perturbation coupled to a detector with temporal resolution and repetitive perturbation which uses the synchrotron pulses for stroboscopic triggering and detection. These schemes are appropriate for different time scales, roughly the milli-, micro- and nanosecond regimes. It appears that time-resolved crystallography is entirely feasible, with an ultimate time resolution limited only by the length of a synchrotron light pulse, some 150 ps at CHESS. (orig.)

Kalman filter approach for uncertainty quantification in time-resolved laser-induced incandescence.

Science.gov (United States)

Hadwin, Paul J; Sipkens, Timothy A; Thomson, Kevin A; Liu, Fengshan; Daun, Kyle J

2018-03-01

Time-resolved laser-induced incandescence (TiRe-LII) data can be used to infer spatially and temporally resolved volume fractions and primary particle size distributions of soot-laden aerosols, but these estimates are corrupted by measurement noise as well as uncertainties in the spectroscopic and heat transfer submodels used to interpret the data. Estimates of the temperature, concentration, and size distribution of soot primary particles within a sample aerosol are typically made by nonlinear regression of modeled spectral incandescence decay, or effective temperature decay, to experimental data. In this work, we employ nonstationary Bayesian estimation techniques to infer aerosol properties from simulated and experimental LII signals, specifically the extended Kalman filter and Schmidt-Kalman filter. These techniques exploit the time-varying nature of both the measurements and the models, and they reveal how uncertainty in the estimates computed from TiRe-LII data evolves over time. Both techniques perform better when compared with standard deterministic estimates; however, we demonstrate that the Schmidt-Kalman filter produces more realistic uncertainty estimates.

Time - resolved thermography at Tokamak T-10

International Nuclear Information System (INIS)

Grunow, C.; Guenther, K.; Lingertat, J.; Chicherov, V.M.; Evstigneev, S.A.; Zvonkov, S.N.

1987-01-01

Thermographic experiments were performed at T-10 tokamak to investigate the thermic coupling of plasma and the limiter. The limiter is an internal equipment of the vacuum vessel of tokamak-type fusion devices and the interaction of plasma with limiter results a high thermal load of limiter for short time. In according to improve the limiter design the temperature distribution on the limiter surface was measured by a time-resolved thermographic method. Typical isotherms and temperature increment curves are presented. This measurement can be used as a systematic plasma diagnostic method because the limiter is installed in the tokamak whereas special additional probes often disturb the plasma discharge. (D.Gy.) 3 refs.; 7 figs

20 CFR 670.991 - How does Job Corps ensure that complaints or disputes are resolved in a timely fashion?

Science.gov (United States)

2010-04-01

... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false How does Job Corps ensure that complaints or disputes are resolved in a timely fashion? 670.991 Section 670.991 Employees' Benefits EMPLOYMENT AND... resolved in a timely fashion? (a) If a complaint is not resolved by the center operator or service provider...

Resolving runaway electron distributions in space, time, and energy

Science.gov (United States)

Paz-Soldan, C.; Cooper, C. M.; Aleynikov, P.; Eidietis, N. W.; Lvovskiy, A.; Pace, D. C.; Brennan, D. P.; Hollmann, E. M.; Liu, C.; Moyer, R. A.; Shiraki, D.

2018-05-01

Areas of agreement and disagreement with present-day models of runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from runaway electrons (REs) with a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent RE transport, and can be used to perform full two-dimensional (energy and pitch-angle) inversions of the RE phase-space distribution. Energy-resolved measurements find qualitative agreement with modeling on the role of collisional and synchrotron damping in modifying the RE distribution shape. Measurements are consistent with predictions of phase-space attractors that accumulate REs, with non-monotonic features observed in the distribution. Temporally resolved measurements find qualitative agreement with modeling on the impact of collisional and synchrotron damping in varying the RE growth and decay rate. Anomalous RE loss is observed and found to be largest at low energy. Possible roles for kinetic instability or spatial transport to resolve these anomalies are discussed.

Structural changes and thermal stability of charged LiNixMnyCozO₂ cathode materials studied by combined in situ time-resolved XRD and mass spectroscopy.

Science.gov (United States)

Bak, Seong-Min; Hu, Enyuan; Zhou, Yongning; Yu, Xiqian; Senanayake, Sanjaya D; Cho, Sung-Jin; Kim, Kwang-Bum; Chung, Kyung Yoon; Yang, Xiao-Qing; Nam, Kyung-Wan

2014-12-24

Thermal stability of charged LiNixMnyCozO2 (NMC, with x + y + z = 1, x:y:z = 4:3:3 (NMC433), 5:3:2 (NMC532), 6:2:2 (NMC622), and 8:1:1 (NMC811)) cathode materials is systematically studied using combined in situ time-resolved X-ray diffraction and mass spectroscopy (TR-XRD/MS) techniques upon heating up to 600 °C. The TR-XRD/MS results indicate that the content of Ni, Co, and Mn significantly affects both the structural changes and the oxygen release features during heating: the more Ni and less Co and Mn, the lower the onset temperature of the phase transition (i.e., thermal decomposition) and the larger amount of oxygen release. Interestingly, the NMC532 seems to be the optimized composition to maintain a reasonably good thermal stability, comparable to the low-nickel-content materials (e.g., NMC333 and NMC433), while having a high capacity close to the high-nickel-content materials (e.g., NMC811 and NMC622). The origin of the thermal decomposition of NMC cathode materials was elucidated by the changes in the oxidation states of each transition metal (TM) cations (i.e., Ni, Co, and Mn) and their site preferences during thermal decomposition. It is revealed that Mn ions mainly occupy the 3a octahedral sites of a layered structure (R3̅m) but Co ions prefer to migrate to the 8a tetrahedral sites of a spinel structure (Fd3̅m) during the thermal decomposition. Such element-dependent cation migration plays a very important role in the thermal stability of NMC cathode materials. The reasonably good thermal stability and high capacity characteristics of the NMC532 composition is originated from the well-balanced ratio of nickel content to manganese and cobalt contents. This systematic study provides insight into the rational design of NMC-based cathode materials with a desired balance between thermal stability and high energy density.

Time Resolved X-Ray Scattering of molecules in Solution

DEFF Research Database (Denmark)

Brandt van Driel, Tim

The dissertation describes the use of Time-Resolved X-ray Diffuse Scattering (TR-XDS) to study photo-induced structural changes in molecules in solution. The application of the technique is exemplified with experiments on two bimetallic molecules. The main focus is on the data-flow and process......)42+ obtained at European Synchrotron Radiation Facility (ESRF) are presented to exemplify TR-XDS at synchrotrons. Similarly, measurements on Ir2(dimen)42+ are used to show the XFEL data-flow and how it deviates from the prior. A method to identify and account for systematic fluctuations...

Ultrafast Structural Dynamics in InSb Probed by Time-Resolved X-Ray Diffraction

International Nuclear Information System (INIS)

Chin, A.H.; Shank, C.V.; Chin, A.H.; Schoenlein, R.W.; Shank, C.V.; Glover, T.E.; Leemans, W.P.; Balling, P.

1999-01-01

Ultrafast structural dynamics in laser-perturbed InSb are studied using time-resolved x-ray diffraction with a novel femtosecond x-ray source. We report the first observation of a delay in the onset of lattice expansion, which we attribute to energy relaxation processes and lattice strain propagation. In addition, we observe direct indications of ultrafast disordering on a subpicosecond time scale. copyright 1999 The American Physical Society

Dynamical observation of lithium insertion/extraction reaction during charge-discharge processes in Li-ion batteries by in situ spatially resolved electron energy-loss spectroscopy.

Science.gov (United States)

Shimoyamada, Atsushi; Yamamoto, Kazuo; Yoshida, Ryuji; Kato, Takehisa; Iriyama, Yasutoshi; Hirayama, Tsukasa

2015-12-01

All-solid-state Li-ion batteries (LIBs) with solid electrolytes are expected to be the next generation devices to overcome serious issues facing conventional LIBs with liquid electrolytes. However, the large Li-ion transfer resistance at the electrode/solid-electrolyte interfaces causes low power density and prevents practical use. In-situ-formed negative electrodes prepared by decomposing the solid electrolyte Li(1+x+3z)Alx(Ti,Ge)(2-x)Si(3z)P(3-z)O12 (LASGTP) with an excess Li-ion insertion reaction are effective electrodes providing low Li-ion transfer resistance at the interfaces. Prior to our work, however, it had still been unclear how the negative electrodes were formed in the parent solid electrolytes. Here, we succeeded in dynamically visualizing the formation by in situ spatially resolved electron energy-loss spectroscopy in a transmission electron microscope mode (SR-TEM-EELS). The Li-ions were gradually inserted into the solid electrolyte region around 400 nm from the negative current-collector/solid-electrolyte interface in the charge process. Some of the ions were then extracted in the discharge process, and the rest were diffused such that the distribution was almost flat, resulting in the negative electrodes. The redox reaction of Ti(4+)/Ti(3+) in the solid electrolyte was also observed in situ during the Li insertion/extraction processes. The in situ SR-TEM-EELS revealed the mechanism of the electrochemical reaction in solid-state batteries. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Transient photoconductivity in InGaN/GaN multiple quantum wells, measured by time-resolved terahertz spectroscopy

DEFF Research Database (Denmark)

Porte, Henrik; Turchinovich, Dmitry; Cooke, David

2009-01-01

Terahertz conductivity of InGaN/GaN MQWs was studied by time-resolved terahertz spectroscopy. Restoration of the built-in piezoelectric field leads to a nonexponential carrier density decay. Terahertz conductivity spectrum is described by the Drude-Smith......Terahertz conductivity of InGaN/GaN MQWs was studied by time-resolved terahertz spectroscopy. Restoration of the built-in piezoelectric field leads to a nonexponential carrier density decay. Terahertz conductivity spectrum is described by the Drude-Smith...

Cluster tool for in situ processing and comprehensive characteriza tion of thin films at high temperatures.

Science.gov (United States)

Wenisch, Robert; Lungwitz, Frank; Hanf, Daniel; Heller, Rene; Zscharschuch, Jens; Hübner, René; von Borany, Johannes; Abrasonis, Gintautas; Gemming, Sibylle; Escobar-Galindo, Ramon; Krause, Matthias

2018-05-31

A new cluster tool for in situ real-time processing and depth-resolved compositional, structural and optical characterization of thin films at temperatures from -100 to 800 °C is described. The implemented techniques comprise magnetron sputtering, ion irradiation, Rutherford backscattering spectrometry, Raman spectroscopy and spectroscopic ellipsometry. The capability of the cluster tool is demonstrated for a layer stack MgO/ amorphous Si (~60 nm)/ Ag (~30 nm), deposited at room temperature and crystallized with partial layer exchange by heating up to 650°C. Its initial and final composition, stacking order and structure were monitored in situ in real time and a reaction progress was defined as a function of time and temperature.

The RATIO method for time-resolved Laue crystallography

International Nuclear Information System (INIS)

Coppens, P.; Pitak, M.; Gembicky, M.; Messerschmidt, M.; Scheins, S.; Benedict, J.; Adachi, S.-I.; Sato, T.; Nozawa, S.; Ichiyanagi, K.; Chollet, M.; Koshihara, S.-Y.

2009-01-01

A RATIO method for analysis of intensity changes in time-resolved pump-probe Laue diffraction experiments is described. The method eliminates the need for scaling the data with a wavelength curve representing the spectral distribution of the source and removes the effect of possible anisotropic absorption. It does not require relative scaling of series of frames and removes errors due to all but very short term fluctuations in the synchrotron beam.

Time-resolved photoelectron spectroscopy and ab initio multiple spawning studies of hexamethylcyclopentadiene

DEFF Research Database (Denmark)

Wolf, T. J. A.; Kuhlman, Thomas Scheby; Schalk, O.

2014-01-01

Time-resolved photoelectron spectroscopy and ab initio multiple spawning were applied to the ultrafast non-adiabatic dynamics of hexamethylcyclopentadiene. The high level of agreement between experiment and theory associates wavepacket motion with a distinct degree of freedom.......Time-resolved photoelectron spectroscopy and ab initio multiple spawning were applied to the ultrafast non-adiabatic dynamics of hexamethylcyclopentadiene. The high level of agreement between experiment and theory associates wavepacket motion with a distinct degree of freedom....

Time-resolved detection of surface plasmon polaritons with a scanning tunneling microscope

DEFF Research Database (Denmark)

Keil, Ulrich Dieter Felix; Ha, T.; Jensen, Jacob Riis

1998-01-01

We present the time-resolved detection of surface plasmon polaritons with an STM. The results indicate that the time resolved signal is due to rectification of coherently superimposed plasmon voltages. The comparison with differential reflectivity measurements shows that the tip itself influences...... the decay of the plasmon-field coherence. Generation of the measured signal at the tunneling junction offers the possibility to observe ultrafast effects with a spatial resolution determined by the tunneling junction...

Direct angle resolved photoemission spectroscopy and ...

Indian Academy of Sciences (India)

Since 1997 we systematically perform direct angle resolved photoemission spectroscopy (ARPES) on in-situ grown thin (< 30 nm) cuprate films. Specifically, we probe low-energy electronic structure and properties of high-c superconductors (HTSC) under different degrees of epitaxial (compressive vs. tensile) strain.

Investigation of Co nanoparticle formation using time-dependent and spatially-resolved X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zinoveva, S

2008-04-15

A crucial step towards controlled synthesis of nanoparticles is the detailed understanding of the various chemical processes that take place during the synthesis. X-ray Absorption Spectroscopy (XAS) is especially suitable for elucidating the type and structure of the intermediate metal species. It is applicable to materials that have no long range order and provides information on both electronic and geometric structures. Here a comparative study is reported of the formation of cobalt nanoparticles via thermolysis of two organometallic precursors dicobalt octacarbonyl (DCO) and alkyne-bridged dicobalt hexacarbonyl (ADH) in the presence of aluminum organics. Using time-dependent XAS a reaction pathway different from both the atom based La Mer model and the Watzky and Finsky autocatalytic surface growth model is observed. Where prior to the nucleation several intermediates are formed and the initial nucleus is composed of Co atoms coordinated with ligands Co{sub n}(CO){sub m} with n=2-3, m=3-5. The formation of Co nanoparticles was also investigated using a reaction different from thermolysis of cobalt carbonyls, namely reduction of Co (II) acetate by sodium borohydrate. Here the combination of microreactor system and spatially resolved XAS allowed ''in situ'' monitoring of the wet chemical synthesis. Several steps of the reaction were spatially resolved in the microreactor. The vertical size of the X-ray beam (50 {mu}m) focused with Kirkpatrick-Baez mirror system, determines the time resolution (better than 2 ms). The results provide direct insight into rapid process of nanoparticles formation and demonstrate the potential of this new technique for the fundamental studies of such type of processes where miniaturization and timeresolution are important. Like in the carbonyls thermolysis no evidence for the reduction of the starting complex to isolated Co{sup 0} atoms followed by nucleation of Co{sup 0} atoms was observed. (orig.)

Investigation of Co nanoparticle formation using time-dependent and spatially-resolved X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Zinoveva, S.

2008-04-15

A crucial step towards controlled synthesis of nanoparticles is the detailed understanding of the various chemical processes that take place during the synthesis. X-ray Absorption Spectroscopy (XAS) is especially suitable for elucidating the type and structure of the intermediate metal species. It is applicable to materials that have no long range order and provides information on both electronic and geometric structures. Here a comparative study is reported of the formation of cobalt nanoparticles via thermolysis of two organometallic precursors dicobalt octacarbonyl (DCO) and alkyne-bridged dicobalt hexacarbonyl (ADH) in the presence of aluminum organics. Using time-dependent XAS a reaction pathway different from both the atom based La Mer model and the Watzky and Finsky autocatalytic surface growth model is observed. Where prior to the nucleation several intermediates are formed and the initial nucleus is composed of Co atoms coordinated with ligands Co{sub n}(CO){sub m} with n=2-3, m=3-5. The formation of Co nanoparticles was also investigated using a reaction different from thermolysis of cobalt carbonyls, namely reduction of Co (II) acetate by sodium borohydrate. Here the combination of microreactor system and spatially resolved XAS allowed ''in situ'' monitoring of the wet chemical synthesis. Several steps of the reaction were spatially resolved in the microreactor. The vertical size of the X-ray beam (50 {mu}m) focused with Kirkpatrick-Baez mirror system, determines the time resolution (better than 2 ms). The results provide direct insight into rapid process of nanoparticles formation and demonstrate the potential of this new technique for the fundamental studies of such type of processes where miniaturization and timeresolution are important. Like in the carbonyls thermolysis no evidence for the reduction of the starting complex to isolated Co{sup 0} atoms followed by nucleation of Co{sup 0} atoms was observed. (orig.)

Time- and Space-Resolved Spectroscopic Investigation on Pi-Conjugated Nanostructures - 2

Science.gov (United States)

2016-01-12

Defocused wide-field fluorescence (DWFI) microscopy suggests that molecular heterogeneities and flexibilities clearly depend on ring size and that site... Confocal   Microscopy   Setup Wild‐field  Microscopy   Setup Femtosecond Z‐scan  experiment Setup Figure 3. Instruments of Time- and space-resolved...approved for public release. 3. Space-Resolved Laser Spectroscopy - Confocal Microscopy - Wild-field Microscopy 4. Non-Linear Spectroscopy

Analytical expressions for time-resolved optically stimulated luminescence experiments in quartz

International Nuclear Information System (INIS)

Pagonis, V.; Lawless, J.; Chen, R.; Chithambo, M.L.

2011-01-01

Optically stimulated luminescence (OSL) signals can be obtained using a time-resolved optical stimulation (TR-OSL) method, also known as pulsed OSL. During TR-OSL measurements, the stimulation and emission of luminescence are experimentally separated in time using short light pulses. This paper presents analytical expressions for the TR-OSL intensity observed during and after such a pulse in quartz experiments. The analytical expressions are derived using a recently published kinetic model which describes thermal quenching phenomena in quartz samples. In addition, analytical expressions are derived for the concentration of electrons in the conduction band during and after the TR-OSL pulse, and for the maximum signals attained during optical stimulation of the samples. The relevance of the model for dosimetric applications is examined, by studying the dependence of the maximum TR-OSL signals on the degree of initial trap filling, and also on the probability of electron retrapping into the dosimetric trap. Analytical expressions are derived for two characteristic times of the TR-OSL mechanism; these times are the relaxation time for electrons in the conduction band, and the corresponding relaxation time for the radiative transition within the luminescence center. The former relaxation time is found to depend on several experimental parameters, while the latter relaxation time depends only on internal parameters characteristic of the recombination center. These differences between the two relaxation times can be explained by the presence of localized and delocalized transitions in the quartz sample. The analytical expressions in this paper are shown to be equivalent to previous analytical expressions derived using a different mathematical approach. A description of thermal quenching processes in quartz based on AlO 4 - /AlO 4 defects is presented, which illustrates the connection between the different descriptions of the luminescence process found in the literature

Developments in time-resolved x-ray research at APS beamline 7ID

Energy Technology Data Exchange (ETDEWEB)

Walko, D. A., E-mail: d-walko@anl.gov; Adams, B. W.; Doumy, G.; Dufresne, E. M.; Li, Yuelin; March, A. M.; Sandy, A. R.; Wang, Jin; Wen, Haidan; Zhu, Yi [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2016-07-27

The 7ID beamline of the Advanced Photon Source (APS) is dedicated to time-resolved research using x-ray imaging, scattering, and spectroscopy techniques. Time resolution is achieved via gated detectors and/or mechanical choppers in conjunction with the time structure of the x-ray beam. Three experimental hutches allow for a wide variety of experimental setups. Major areas of research include atomic, molecular, and optical physics; chemistry; condensed matter physics in the bulk, thin film, and surface regimes; and fluid-spray dynamics. Recent developments in facilities at 7ID include a high-power, high-repetition-rate picosecond laser to complement the 1 kHz ultrafast laser. For the ultrafast laser, a newly commissioned optical parametric amplifier provides pump wavelength from 0.2 to 15 µm with energy per pulse up to 200 µJ. A nanodiffraction station has also been commissioned, using Fresnel zone-plate optics to achieve a focused x-ray spot of 300 nm. This nanoprobe is not only used to spatially resolve the evolution of small features in samples after optical excitation, but also has been combined with an intense THz source to study material response under ultrafast electric fields.

Time-Resolved Fluorescent Immunochromatography of Aflatoxin B1 in Soybean Sauce: A Rapid and Sensitive Quantitative Analysis.

Science.gov (United States)

Wang, Du; Zhang, Zhaowei; Li, Peiwu; Zhang, Qi; Zhang, Wen

2016-07-14

Rapid and quantitative sensing of aflatoxin B1 with high sensitivity and specificity has drawn increased attention of studies investigating soybean sauce. A sensitive and rapid quantitative immunochromatographic sensing method was developed for the detection of aflatoxin B1 based on time-resolved fluorescence. It combines the advantages of time-resolved fluorescent sensing and immunochromatography. The dynamic range of a competitive and portable immunoassay was 0.3-10.0 µg·kg(-1), with a limit of detection (LOD) of 0.1 µg·kg(-1) and recoveries of 87.2%-114.3%, within 10 min. The results showed good correlation (R² > 0.99) between time-resolved fluorescent immunochromatographic strip test and high performance liquid chromatography (HPLC). Soybean sauce samples analyzed using time-resolved fluorescent immunochromatographic strip test revealed that 64.2% of samples contained aflatoxin B1 at levels ranging from 0.31 to 12.5 µg·kg(-1). The strip test is a rapid, sensitive, quantitative, and cost-effective on-site screening technique in food safety analysis.

MCNP simulations of a new time-resolved Compton scattering imaging technique

International Nuclear Information System (INIS)

Ilan, Y.

2004-01-01

Medical images of human tissue can be produced using Computed Tomography (CT), Positron Emission Tomography (PET), Ultrasound or Magnetic Resonance Imaging (MRI). In all of the above techniques, in order to get a three-dimensional (3D) image, one has to rotate or move the source, the detectors or the scanned target. This procedure is complicated, time consuming and increases the cost and weight of the scanning equipment. Time resolved optical tomography has been suggested as an alternative to the above conventional methods. This technique implies near infrared light (NIR) and fast time-resolved detectors to obtain a 3D image of the scanned target. However, due to the limited penetration of the NIR light in the tissue, the application of this technique is limited to soft tissue like a female breast or a premature infant brain

On the theory of time-resolved x-ray diffraction

DEFF Research Database (Denmark)

Henriksen, Niels Engholm; Møller, Klaus Braagaard

2008-01-01

We derive the basic theoretical formulation for X-ray diffraction with pulsed fields, using a fully quantized description of light and matter. Relevant time scales are discussed for coherent as well as incoherent X-ray pulses, and we provide expressions to be used for calculation...... of the experimental diffraction signal for both types of X-ray sources. We present a simple analysis of time-resolved X-ray scattering for direct bond breaking in diatomic molecules. This essentially analytical approach highlights the relation between the signal and the time-dependent quantum distribution...

Fast time-resolved electrostatic force microscopy: Achieving sub-cycle time resolution

Energy Technology Data Exchange (ETDEWEB)

Karatay, Durmus U.; Harrison, Jeffrey S.; Glaz, Micah S.; Giridharagopal, Rajiv; Ginger, David S., E-mail: ginger@chem.washington.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)

2016-05-15

The ability to measure microsecond- and nanosecond-scale local dynamics below the diffraction limit with widely available atomic force microscopy hardware would enable new scientific studies in fields ranging from biology to semiconductor physics. However, commercially available scanning-probe instruments typically offer the ability to measure dynamics only on time scales of milliseconds to seconds. Here, we describe in detail the implementation of fast time-resolved electrostatic force microscopy using an oscillating cantilever as a means to measure fast local dynamics following a perturbation to a sample. We show how the phase of the oscillating cantilever relative to the perturbation event is critical to achieving reliable sub-cycle time resolution. We explore how noise affects the achievable time resolution and present empirical guidelines for reducing noise and optimizing experimental parameters. Specifically, we show that reducing the noise on the cantilever by using photothermal excitation instead of piezoacoustic excitation further improves time resolution. We demonstrate the discrimination of signal rise times with time constants as fast as 10 ns, and simultaneous data acquisition and analysis for dramatically improved image acquisition times.

Time-resolved X-ray scattering program at the Advanced Photon Source

International Nuclear Information System (INIS)

Rodricks, B.

1994-01-01

The Time-Resolved Scattering Program's goal is the development of instruments and techniques for time-resolved studies. This entails the development of wide bandpass and focusing optics, high-speed detectors, mechanical choppers, and components for the measurement and creation of changes in samples. Techniques being developed are pump-probe experiments, single-bunch scattering experiments, high-speed white and pink beam Laue scattering, and nanosecond to microsecond synchronization of instruments. This program will be carried out primarily from a white-beam, bend-magnet source, experimental station, 1-BM-B, that immediately follows the first optics enclosure (1-BM-A). This paper will describe the experimental station and instruments under development to carry out the program

Space- and time-resolved raman and breakdown spectroscopy: advanced lidar techniques

Science.gov (United States)

Silviu, Gurlui; Marius Mihai, Cazacu; Adrian, Timofte; Oana, Rusu; Georgiana, Bulai; Dimitriu, Dan

2018-04-01

DARLIOES - the advanced LIDAR is based on space- and time-resolved RAMAN and breakdown spectroscopy, to investigate chemical and toxic compounds, their kinetics and physical properties at high temporal (2 ns) and spatial (1 cm) resolution. The high spatial and temporal resolution are needed to resolve a large variety of chemical troposphere compounds, emissions from aircraft, the self-organization space charges induced light phenomena, temperature and humidity profiles, ice nucleation, etc.

Thermally activated delayed fluorescence of fluorescein derivative for time-resolved and confocal fluorescence imaging.

Science.gov (United States)

Xiong, Xiaoqing; Song, Fengling; Wang, Jingyun; Zhang, Yukang; Xue, Yingying; Sun, Liangliang; Jiang, Na; Gao, Pan; Tian, Lu; Peng, Xiaojun

2014-07-09

Compared with fluorescence imaging utilizing fluorophores whose lifetimes are in the order of nanoseconds, time-resolved fluorescence microscopy has more advantages in monitoring target fluorescence. In this work, compound DCF-MPYM, which is based on a fluorescein derivative, showed long-lived luminescence (22.11 μs in deaerated ethanol) and was used in time-resolved fluorescence imaging in living cells. Both nanosecond time-resolved transient difference absorption spectra and time-correlated single-photon counting (TCSPC) were employed to explain the long lifetime of the compound, which is rare in pure organic fluorophores without rare earth metals and heavy atoms. A mechanism of thermally activated delayed fluorescence (TADF) that considers the long wavelength fluorescence, large Stokes shift, and long-lived triplet state of DCF-MPYM was proposed. The energy gap (ΔEST) of DCF-MPYM between the singlet and triplet state was determined to be 28.36 meV by the decay rate of DF as a function of temperature. The ΔE(ST) was small enough to allow efficient intersystem crossing (ISC) and reverse ISC, leading to efficient TADF at room temperature. The straightforward synthesis of DCF-MPYM and wide availability of its starting materials contribute to the excellent potential of the compound to replace luminescent lanthanide complexes in future time-resolved imaging technologies.

Real-time visualization of the vibrational wavepacket dynamics in electronically excited pyrimidine via femtosecond time-resolved photoelectron imaging

Science.gov (United States)

Li, Shuai; Long, Jinyou; Ling, Fengzi; Wang, Yanmei; Song, Xinli; Zhang, Song; Zhang, Bing

2017-07-01

The vibrational wavepacket dynamics at the very early stages of the S1-T1 intersystem crossing in photoexcited pyrimidine is visualized in real time by femtosecond time-resolved photoelectron imaging and time-resolved mass spectroscopy. A coherent superposition of the vibrational states is prepared by the femtosecond pump pulse at 315.3 nm, resulting in a vibrational wavepacket. The composition of the prepared wavepacket is directly identified by a sustained quantum beat superimposed on the parent-ion transient, possessing a frequency in accord with the energy separation between the 6a1 and 6b2 states. The dephasing time of the vibrational wavepacket is determined to be 82 ps. More importantly, the variable Franck-Condon factors between the wavepacket components and the dispersed cation vibrational levels are experimentally illustrated to identify the dark state and follow the energy-flow dynamics on the femtosecond time scale. The time-dependent intensities of the photoelectron peaks originated from the 6a1 vibrational state exhibit a clear quantum beating pattern with similar periodicity but a phase shift of π rad with respect to those from the 6b2 state, offering an unambiguous picture of the restricted intramolecular vibrational energy redistribution dynamics in the 6a1/6b2 Fermi resonance.

The aquatic real-time monitoring network; in-situ optical sensors for monitoring the nation's water quality

Science.gov (United States)

Pellerin, Brian A.; Bergamaschi, Brian A.; Murdoch, Peter S.; Downing, Bryan D.; Saraceno, John Franco; Aiken, George R.; Striegl, Robert G.

2011-01-01

Floods, hurricanes, and longer-term changes in climate and land use can have profound effects on water quality due to shifts in hydrologic flow paths, water residence time, precipitation patterns, connectivity between rivers and uplands, and many other factors. In order to understand and respond to changes in hydrology and water quality, resource managers and policy makers have a need for accurate and early indicators, as well as the ability to assess possible mechanisms and likely outcomes. In-situ optical sensors-those making continuous measurements of constituents by absorbance or fluorescence properties in the environment at timescales of minutes to years-have a long history in oceanography for developing highly resolved concentrations and fluxes, but are not commonly used in freshwater systems. The United States Geological Survey (USGS) has developed the Aquatic Real-Time Monitoring Network, with high-resolution optical data collection for organic carbon, nutrients, and sediment in large coastal rivers, along with continuous measurements of discharge, water temperature, and dissolved inorganic carbon. The collecting of continuous water-quality data in the Nation?s waterways has revealed temporal trends and spatial patterns in constituents that traditional sampling approaches fail to capture, and will serve a critical role in monitoring, assessment and decision-making in a rapidly changing landscape.

Time-resolved stimulated emission depletion and energy transfer dynamics in two-photon excited EGFP

Science.gov (United States)

Masters, T. A.; Robinson, N. A.; Marsh, R. J.; Blacker, T. S.; Armoogum, D. A.; Larijani, B.; Bain, A. J.

2018-04-01

Time and polarization-resolved stimulated emission depletion (STED) measurements are used to investigate excited state evolution following the two-photon excitation of enhanced green fluorescent protein (EGFP). We employ a new approach for the accurate STED measurement of the hitherto unmeasured degree of hexadecapolar transition dipole moment alignment ⟨α40 ⟩ present at a given excitation-depletion (pump-dump) pulse separation. Time-resolved polarized fluorescence measurements as a function of pump-dump delay reveal the time evolution of ⟨α40 ⟩ to be considerably more rapid than predicted for isotropic rotational diffusion in EGFP. Additional depolarization by homo-Förster resonance energy transfer is investigated for both ⟨α20 ⟩ (quadrupolar) and ⟨α40 ⟩ transition dipole alignments. These results point to the utility of higher order dipole correlation measurements in the investigation of resonance energy transfer processes.

Ultrafast time-resolved faraday rotation in EuO thin films.

Science.gov (United States)

Liu, F; Makino, T; Yamasaki, T; Ueno, K; Tsukazaki, A; Fukumura, T; Kong, Y; Kawasaki, M

2012-06-22

We have investigated the ultrafast spin dynamics in EuO thin films by time-resolved Faraday rotation spectroscopy. The photoinduced magnetization is found to be increased in a transient manner, accompanied with subsequent demagnetization. The dynamical magnetization enhancement showed a maximum slightly below the Curie temperature with prolonged tails toward both lower and higher temperatures and dominates the demagnetization counterpart at 55 K. The magnetization enhancement component decays in ~1 ns. The realization of the transient collective ordering is attributable to the enhancement of the f-d exchange interaction.

Mix and Inject: Reaction Initiation by Diffusion for Time-Resolved Macromolecular Crystallography

Directory of Open Access Journals (Sweden)

Marius Schmidt

2013-01-01

Full Text Available Time-resolved macromolecular crystallography unifies structure determination with chemical kinetics, since the structures of transient states and chemical and kinetic mechanisms can be determined simultaneously from the same data. To start a reaction in an enzyme, typically, an initially inactive substrate present in the crystal is activated. This has particular disadvantages that are circumvented when active substrate is directly provided by diffusion. However, then it is prohibitive to use macroscopic crystals because diffusion times become too long. With small micro- and nanocrystals diffusion times are adequately short for most enzymes and the reaction can be swiftly initiated. We demonstrate here that a time-resolved crystallographic experiment becomes feasible by mixing substrate with enzyme nanocrystals which are subsequently injected into the X-ray beam of a pulsed X-ray source.

Plastique: A synchrotron radiation beamline for time resolved fluorescence in the frequency domain

Science.gov (United States)

De Stasio, Gelsomina; Zema, N.; Antonangeli, F.; Savoia, A.; Parasassi, T.; Rosato, N.

1991-06-01

PLASTIQUE is the only synchrotron radiation beamline in the world that performs time resolved fluorescence experiments in frequency domain. These experiments are extremely valuable sources of information on the structure and dynamics of molecules. We describe the beamline and some initial data.

Dissolved Air Flotation of arsenic adsorbent particles

Directory of Open Access Journals (Sweden)

Mario Enrique Santander Muñoz

2015-01-01

Full Text Available The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF and dissolved air flotation (DAF. A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic poly-acrylamide (NALCO 9808 as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with flotation studies to determine the removal efficiency of adsorbents particles. The results achieved indicate that the adsorption kinetic of arsenic is very rapid and that in range of pH’s from 2 to 7 the adsorption percentages remain constant. The equilibrium conditions were achieved in 60 minutes and about 95% of arsenic was adsorbed when used an adsorbent concentration of 2 g/L and pH 6.3. The maximum adsorption capacity of adsorbent particles was 4.96 mg/g. The mean free energy of adsorption (E was found to be 2.63 kJ/mol, which suggests physisorption. The results of the flotation studies demonstrated that when synthetic effluents with 8.9 mg/L of arsenic were treated under the following experimental conditions; 2 g/L of adsorbent particles, 120 mg/L of Fe(III, 2 mg/L of Nalco 9808, 20 mg/L of sodium oleate, and 40% of recycle ratio in the DAF, it was possible to reach 98% of arsenic removal and 6.3 NTU of residual turbidity in clarified synthetic effluent.

New methods and applications in time-resolved X-ray absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Stoetzel, Jan Eric

2012-07-01

Recent experimental advances and developments in the QEXAFS technique were presented along with new applications in the disciplines of catalysis and surface science. Both performance and user-friendliness of the QEXAFS method were significantly improved, while the applicability of QEXAFS was extended by newly designed mechanics. The application of a fast angular encoder proved to be capable to sample the continuously changing Bragg angle of the monochromator crystal synchronized to the acquired absorption data. A new data acquisition system was designed, based on a multifunctional ADC board, which provides high acquisition frequencies, while low noise acquisition could be achieved due to the provided differential acquisition mode. Additionally, control of all experimental devices as current amplifiers, monochromator motors and sample stages were implemented to further increase the efficiency of the experimental setup for QEFAS measurements. In order to simplify the processing of the huge generated QEXAFS raw data files, a completely new software tool for data analysis was designed, which provides not only the basic procedures of QEXAFS data analysis, but also many approaches customized for time-resolved data. Apart from technical advances, various experiments were performed with QEXAFS to gain new insights into the complex processes of several catalytic reactions, the thermal decomposition of metal oxalates, as well as layer growth processes and reactions on rough surfaces. Supported Pd catalysts were investigated during catalytic partial oxidation of methane, whereby oscillations in the conversion were linked to structural changes of the catalyst. Kinetic oscillations were also investigated on a supported Pt catalyst during the extinction of CO oxidation induced by decreasing temperature. Modulated experiments were investigated (i) on supported Pt-Rh/Al{sub 2}O{sub 3} catalysts during active catalytic partial oxidation in switching gas atmospheres of methane and

Developments in time-resolved high pressure x-ray diffraction using rapid compression and decompression

International Nuclear Information System (INIS)

Smith, Jesse S.; Sinogeikin, Stanislav V.; Lin, Chuanlong; Rod, Eric; Bai, Ligang; Shen, Guoyin

2015-01-01

Complementary advances in high pressure research apparatus and techniques make it possible to carry out time-resolved high pressure research using what would customarily be considered static high pressure apparatus. This work specifically explores time-resolved high pressure x-ray diffraction with rapid compression and/or decompression of a sample in a diamond anvil cell. Key aspects of the synchrotron beamline and ancillary equipment are presented, including source considerations, rapid (de)compression apparatus, high frequency imaging detectors, and software suitable for processing large volumes of data. A number of examples are presented, including fast equation of state measurements, compression rate dependent synthesis of metastable states in silicon and germanium, and ultrahigh compression rates using a piezoelectric driven diamond anvil cell

Life-time resolved emission spectra in CdCl2 crystals

International Nuclear Information System (INIS)

Kawabata, S.; Nakagawa, H.; Kitaura, M.

2005-01-01

The emission spectrum of CdCl 2 is composed of ultraviolet (UV) and yellow (Y) bands peaking at 3.70 and 2.30 eV, respectively. In order to determine the initial states of the Y-luminescence, decay curves of the Y-emission were measured at 8K by varying emission energy in the range from 1.64 eV to 3.13 eV. The observed decay curves are composed of two or three exponential components. The values of lifetime for them were 900, 460 and 60 μs. The emission spectrum for each decay component, i.e., life-time resolved emission spectrum, was analyzed by the observed decay curves. The emission spectrum for the component of 460 μs lifetime exhibits a dominant band at 2.30 eV and a satellite band at 3.03 eV. The emission spectrum for the component of 60 μs lifetime is reproduced by the three Gaussian bands peaking at 2.21, 2.65 and 2.87 eV. For the component of 900 μs lifetime, only a single band appears at 1.73 eV. The origin of the emission bands in life-time resolved emission spectra is briefly discussed, and the initial states of Y-luminescence are explained by the excited states of a [Cd 2+ Cl - 6 ] 4- complex molecular ion. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Time-resolved X-ray studies using third generation synchrotron radiation sources

International Nuclear Information System (INIS)

Mills, D.M.

1991-10-01

The third generation, high-brilliance, hard x-ray, synchrotron radiation (SR) sources currently under construction (ESRF at Grenoble, France; APS at Argonne, Illinois; and SPring-8 at Harima, Japan) will usher in a new era of x-ray experimentation for both physical and biological sciences. One of the most exciting areas of experimentation will be the extension of x-ray scattering and diffraction techniques to the study of transient or time-evolving systems. The high repetition rate, short-pulse duration, high brilliance, and variable spectral bandwidth of these sources make them ideal for x-ray time-resolved studies. The temporal properties (bunch length, interpulse period, etc.) of these new sources will be summarized. Finally, the scientific potential and the technological challenges of time-resolved x-ray scattering from these new sources will be described. 13 refs., 4 figs

In situ microscopy of the self-assembly of branched nanocrystals in solution

Science.gov (United States)

Sutter, Eli; Sutter, Peter; Tkachenko, Alexei V.; Krahne, Roman; de Graaf, Joost; Arciniegas, Milena; Manna, Liberato

2016-04-01

Solution-phase self-assembly of nanocrystals into mesoscale structures is a promising strategy for constructing functional materials from nanoscale components. Liquid environments are key to self-assembly since they allow suspended nanocrystals to diffuse and interact freely, but they also complicate experiments. Real-time observations with single-particle resolution could have transformative impact on our understanding of nanocrystal self-assembly. Here we use real-time in situ imaging by liquid-cell electron microscopy to elucidate the nucleation and growth mechanism and properties of linear chains of octapod-shaped nanocrystals in their native solution environment. Statistical mechanics modelling based on these observations and using the measured chain-length distribution clarifies the relative importance of dipolar and entropic forces in the assembly process and gives direct access to the interparticle interaction. Our results suggest that monomer-resolved in situ imaging combined with modelling can provide unprecedented quantitative insight into the microscopic processes and interactions that govern nanocrystal self-assembly in solution.

In situ and real-time atomic force microscopy studies of the stability of oligothiophene langmuir-blodgett monolayers in liquid

KAUST Repository

Yin, Naining

2014-03-20

Oligothiophene thin films have been considered as promising material for molecular electronics due to their desirable electronic properties and high structural stability under ambient conditions. To ensure performance in devices the functional structures, such as individual ordered domains, must be stable under practical and operational conditions or environments including exposure to various media. This work investigates the structure of oligothiophene Langmuir-Blodgett (LB) films upon exposure to liquid media such as water, ethanol (EtOH), and mixed tetrahydrofuran (THF)/EtOH solutions. The LB films form islands ranging from 500 nm up to 1 μm consisting of densely packed oligothiophene molecules. These islands are surrounded by bare substrate and loosely packed adsorbates. In situ and time-dependent AFM images were acquired to reveal the structural evolution, from which degradation pathways and kinetics are extracted. Degradation of these LB films initiates and propagates from intraisland defect sites, such as cracks and pin holes, whereas the edges of islands remain intact on the surface. The observations appear to be in contrast to the known degradation mechanism among self-assembled monolayers, such as alkanethiols on gold, which initiates and progresses at domain boundaries. Rationale for the observed degradation processes will also be discussed. © 2014 American Chemical Society.

Determination of quenching coefficients by time resolved emission spectroscopy

International Nuclear Information System (INIS)

Gans, T.; Schulz-von der Gathen, V.; Doebele, H.F.

2001-01-01

Capacitively coupled RF discharges (CCRF discharges) at 13.56 MHz in hydrogen exhibit a field reversal phase of about 10 ns during which an intense electron current provides collisional excitation, within the sheath region. After this strongly dominant short pulsed electron impact excitation, it is possible to determine quenching coefficients from the lifetime of the fluorescence at various pressures by time resolved OES even for high energy levels and without any restrictions of optical selection rules. This novel technique allows the measurement of quenching coefficients for atomic and molecular emission lines of hydrogen itself, as well as for emission lines of small admixtures (e.g. noble gases) to the hydrogen discharge, since with a fast gate-able ICCD camera operating at 13.56 MHz it is possible to measure even faint emission lines temporally resolved

Determination of quenching coefficients by time resolved emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Gans, T.; Schulz-von der Gathen, V.; Doebele, H.F. [Essen Univ. (Gesamthochschule) (Germany). Inst. fuer Laser- und Plasmaphysik

2001-07-01

Capacitively coupled RF discharges (CCRF discharges) at 13.56 MHz in hydrogen exhibit a field reversal phase of about 10 ns during which an intense electron current provides collisional excitation, within the sheath region. After this strongly dominant short pulsed electron impact excitation, it is possible to determine quenching coefficients from the lifetime of the fluorescence at various pressures by time resolved OES even for high energy levels and without any restrictions of optical selection rules. This novel technique allows the measurement of quenching coefficients for atomic and molecular emission lines of hydrogen itself, as well as for emission lines of small admixtures (e.g. noble gases) to the hydrogen discharge, since with a fast gate-able ICCD camera operating at 13.56 MHz it is possible to measure even faint emission lines temporally resolved.

Time-resolved three-dimensional magnetic resonance velocity mapping of chronic thoracic aortic dissection. A preliminary investigation

International Nuclear Information System (INIS)

Amano, Yasuo; Sekine, Tetsuro; Tanaka, Keiji; Takagi, Ryo; Kumita, Shinichiro; Suzuki, Yuriko

2011-01-01

The blood flow patterns of chronic thoracic aortic dissection are complicated, and their clinical significance remains unknown. We evaluated the technical and clinical potentials of time-resolved 3-dimensional (3D) magnetic resonance (MR) velocity mapping for assessing these patterns. We used data collected from time-resolved 3D phase-contrast MR imaging of 16 patients with chronic thoracic aortic dissection to generate time-resolved 3D MR velocity mapping that included 3D streamline and path line. We investigated blood flow patterns of this disease in the mapping and compared them with the morphological changes of the patent false lumen. Time-resolved 3D MR velocity mapping visualized rapid flow at the entry and in the true lumen immediately distal to the entry. We observed slower helical or laminar flow in the patent false lumen. In patients with disease progression, slower helical flow following rapid entry jet collided with the outer wall of the false lumen and was also observed in a growing ulcer-like projection. We showed the potential of time-resolved 3D MR velocity mapping for visualizing pathologic flow patterns related to chronic thoracic aortic dissection. (author)

Time-resolved photoelectron spectroscopy of IR-driven electron dynamics in a charge transfer model system.

Science.gov (United States)

Falge, Mirjam; Fröbel, Friedrich Georg; Engel, Volker; Gräfe, Stefanie

2017-08-02

If the adiabatic approximation is valid, electrons smoothly adapt to molecular geometry changes. In contrast, as a characteristic of diabatic dynamics, the electron density does not follow the nuclear motion. Recently, we have shown that the asymmetry in time-resolved photoelectron spectra serves as a tool to distinguish between these dynamics [Falge et al., J. Phys. Chem. Lett., 2012, 3, 2617]. Here, we investigate the influence of an additional, moderately intense infrared (IR) laser field, as often applied in attosecond time-resolved experiments, on such asymmetries. This is done using a simple model for coupled electronic-nuclear motion. We calculate time-resolved photoelectron spectra and their asymmetries and demonstrate that the spectra directly map the bound electron-nuclear dynamics. From the asymmetries, we can trace the IR field-induced population transfer and both the field-driven and intrinsic (non-)adiabatic dynamics. This holds true when considering superposition states accompanied by electronic coherences. The latter are observable in the asymmetries for sufficiently short XUV pulses to coherently probe the coupled states. It is thus documented that the asymmetry is a measure for phases in bound electron wave packets and non-adiabatic dynamics.

Time-resolved spectroscopy of the probe fluorescence in the study of human blood protein dynamic structure on SR beam

International Nuclear Information System (INIS)

Dobretsov, G.E.; Kurek, N.K.; Syrejshchikova, T.I.; Yakimenko, M.N.; Clarke, D.T.; Jones, G.R.; Munro, I.H.

2000-01-01

Time-resolved spectroscopy on the SRS of the Daresbury Laboratory was used for the study of the human serum lipoproteins and human blood albumins with fluorescent probes K-37 and K-35, developed in Russia. The probe K-37 was found sensitive to the difference in dynamic properties of the lipid objects. Two sets of the parameters were used for the description of lipid dynamic structure: (1) time-resolved fluorescence spectra and (2) time-resolved fluorescence depolarization as a function of rotational mobility of lipid molecules. Each measured dynamic parameter reflected the monotonous changes of dynamic properties in the range: lipid spheres-very low density lipoproteins-low density lipoproteins-high density lipoproteins-phospholipid liposomes. The range is characterized by the increase of the ratio polar/ nonpolar lipids. Thus, time-resolved fluorescence could be used to detect some structural modifications in lipoproteins related to atherosclerosis and subsequent cardiovascular diseases development

Rare Earth Elements as Potential Biosignatures on Mars in SuperCam Time Resolved Laser Fluorescence Spectroscopy Data

Science.gov (United States)

Ollila, A.; Beyssac, O.; Sharma, S. K.; Misra, A. K.; Clegg, S. M.; Gauthier, M.; Wiens, R. C.; Maurice, S.; Gasnault, O.; Lanza, N.

2017-12-01

The rare earth elements (REE, La to Lu) are a group of elements with similar chemical properties that are generally present in geologic materials at trace concentrations. REEs may be concentrated via processes such as igneous fractional crystallization in accessory minerals, e.g. apatite, zircon, and titanite. Additionally, however, concentrations of REE may serve to identify regions of high astrobiological interest. For example, Fe-oxyhydroxide deposits in hydrothermal vent systems and biologically related manganese nodules may be enriched in REEs. REEs have not been measured in situ on Mars, therefore their prevalence and distribution on Mars is as yet unknown, except as observed in martian meteorites. SuperCam is a survey instrument that will analyze materials around the Mars 2020 rover using a variety of spectral techniques including laser-induced breakdown spectroscopy (LIBS), Raman, VIS-IR, and time-resolved laser fluorescence (TRLF) spectroscopy. Recently, the SuperCam Engineering Development Unit was tested at the Los Alamos National Laboratory for its capabilities to detect REEs in minerals using TRLF spectroscopy. While this instrument was not designed to precisely replicate the flight model, the spectral resolution and light transmission was sufficient to obtain TRLF spectra on a number of minerals demonstrating a variety of REE luminescent centers. These include apatite (Sm3+, Nd3+, Eu3+, Dy3+), fluorite (Ho3+, Sm3+, Dy3+, Nd3+), and zircon (Er3+, Pr3+, Nd3+). Future work includes expanding this suite to include minerals associated with biological activities, for example Mn-oxides (desert varnish and manganese nodules), hydrothermal Fe-oxides, and stromatolite-associated carbonates. In this way and in combination with its other techniques, SuperCam may direct the rover team to perform further analyses of similar samples by the in situ chemical and mineralogical suite of instruments, or aid in prioritization for sample return.

Dual time-resolved temperature-jump fluorescence and infrared spectroscopy for the study of fast protein dynamics.

Science.gov (United States)

Davis, Caitlin M; Reddish, Michael J; Dyer, R Brian

2017-05-05

Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of jump induced difference spectrum from 50ns to 0.5ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.

Probing long-range structural order in SnPc/Ag(111) by umklapp process assisted low-energy angle-resolved photoelectron spectroscopy

Science.gov (United States)

Jauernik, Stephan; Hein, Petra; Gurgel, Max; Falke, Julian; Bauer, Michael

2018-03-01

Laser-based angle-resolved photoelectron spectroscopy is performed on tin-phthalocyanine (SnPc) adsorbed on silver Ag(111). Upon adsorption of SnPc, strongly dispersing bands are observed which are identified as secondary Mahan cones formed by surface umklapp processes acting on photoelectrons from the silver substrate as they transit through the ordered adsorbate layer. We show that the photoemission data carry quantitative structural information on the adsorbate layer similar to what can be obtained from a conventional low-energy electron diffraction (LEED) study. More specifically, we compare photoemission data and LEED data probing an incommensurate-to-commensurate structural phase transition of the adsorbate layer. Based on our results we propose that Mahan-cone spectroscopy operated in a pump-probe configuration can be used in the future to probe structural dynamics at surfaces with a temporal resolution in the sub-100-fs regime.

Resolving Peak Ground Displacements in Real-Time GNSS PPP Solutions

Science.gov (United States)

Hodgkinson, K. M.; Mencin, D.; Mattioli, G. S.; Sievers, C.; Fox, O.

2017-12-01

The goal of early earthquake warning (EEW) systems is to provide warning of impending ground shaking to the public, infrastructure managers, and emergency responders. Shaking intensity can be estimated using Ground Motion Prediction Equations (GMPEs), but only if site characteristics, hypocentral distance and event magnitude are known. In recent years work has been done analyzing the first few seconds of the seismic P wave to derive event location and magnitude. While initial rupture locations seem to be sufficiently constrained, it has been shown that P-wave magnitude estimates tend to saturate at M>7. Regions where major and great earthquakes occur may therefore be vulnerable to an underestimation of shaking intensity if only P waves magnitudes are used. Crowell et al., (2013) first demonstrated that Peak Ground Displacement (PGD) from long-period surface waves recorded by GNSS receivers could provide a source-scaling relation that does not saturate with event magnitude. GNSS PGD derived magnitudes could improve the accuracy of EEW GMPE calculations. If such a source-scaling method were to be implemented in EEW algorithms it is critical that the noise levels in real-time GNSS processed time-series are low enough to resolve long-period surface waves. UNAVCO currently operates 770 real-time GNSS sites, most of which are located along the North American-Pacific Plate Boundary. In this study, we present an analysis of noise levels observed in the GNSS Precise Point Positioning (PPP) solutions generated and distributed in real-time by UNAVCO for periods from seconds to hours. The analysis is performed using the 770 sites in the real-time network and data collected through July 2017. We compare noise levels determined from various monument types and receiver-antenna configurations. This analysis gives a robust estimation of noise levels in PPP solutions because the solutions analyzed are those that were generated in real-time and thus contain all the problems observed

Transfer of chirality from adsorbed chiral molecules to the substrates highlighted by circular dichroism in angle-resolved valence photoelectron spectroscopy

DEFF Research Database (Denmark)

Contini, G.; Turchini, S.; Sanna, Simone

2012-01-01

Studies of self-assembled chiral molecules on achiral metallic surfaces have mostly focused on the determination of the geometry of adsorbates and their electronic structure. The aim of this paper is to provide direct information on the chirality character of the system and on the chirality...... transfer from molecules to substrate by means of circular dichroism in the angular distribution of valence photoelectrons for the extended domain of the chiral self-assembled molecular structure, formed by alaninol adsorbed on Cu(100). We show, by the dichroic behavior of a mixed molecule–copper valence...... state, that the presence of molecular chiral domains induces asymmetry in the interaction with the substrate and locally transfers the chiral character to the underlying metal atoms participating in the adsorption process; combined information related to the asymmetry of the initial electronic state...

PLASTIQUE: A synchrotron radiation beamline for time resolved fluorescence in the frequency domain

International Nuclear Information System (INIS)

De Stasio, G.; Zema, N.; Antonangeli, F.; Parasassi, T.; Rosato, N.

1991-01-01

PLASTIQUE is the only synchrotron radiation beamline in the world that performs time resolved fluorescence experiments in the frequency domain. These experiments are extremely valuable sources of informations on the structure and dynamics of molecules. The beamline and some examples of initial data are described

Time-resolved laser-induced fluorescence system

Science.gov (United States)

Bautista, F. J.; De la Rosa, J.; Gallegos, F. J.

2006-02-01

Fluorescence methods are being used increasingly in the measurement of species concentrations in gases, liquids and solids. Laser induced fluorescence is spontaneous emission from atoms or molecules that have been excited by laser radiation. Here we present a time resolved fluorescence instrument that consists of a 5 μJ Nitrogen laser (337.1 nm), a sample holder, a quartz optical fiber, a spectrometer, a PMT and a PC that allows the measurement of visible fluorescence spectra (350-750 nm). Time response of the system is approximately 5 ns. The instrument has been used in the measurement of colored bond paper, antifreeze, diesel, cochineal pigment and malignant tissues. The data acquisition was achieved through computer control of a digital oscilloscope (using General Purpose Interface Bus GPIB) and the spectrometer via serial (RS232). The instrument software provides a graphic interface that lets make some data acquisition tasks like finding fluorescence spectra, and fluorescence lifetimes. The software was developed using the Lab-View 6i graphic programming package and can be easily managed in order to add more functions to it.

Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sentef, Michael; Kemper, Alexander F.; Moritz, Brian; Freericks, James K.; Shen, Zhi-Xun; Devereaux, Thomas P.

2013-12-26

Nonequilibrium pump-probe time-domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system, we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for “slow” versus “fast” recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.

Zinc-aluminates for an in situ sulfur reduction in cracked gasoline

Energy Technology Data Exchange (ETDEWEB)

Quintana-Solorzano, R.; Valente, J.S.; Hernandez-Beltran, F.J.; Castillo-Araiza, C.O. [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas Norte 152 C.P., 07730 Mexico, D.F. (Mexico)

2008-05-30

Using additives remains as an attractive alternative for an in situ sulfur reduction in cracked gasoline since it is a practical, flexible and economical option. Zinc-aluminates prepared by the sol-gel method are used as additives for reducing sulfur in gasoline from the cracking of a high-sulfur feed in a fixed-bed bench reactor. Products distribution and feed conversion are not dramatically altered after incorporating the additive to the base catalyst with some effect on gasoline and its octane number and coke. A decrease in the gasoline sulfur content of up to 35 wt% including benzothiophene, and up to 50% excluding benzothiophene, is observed when blending the zinc-aluminates to the base catalyst, which is caused by lowering the C{sub 1} to C{sub 4} alkyl-thiophenes content. The zinc content of the zinc-aluminates has a positive effect on the gasoline sulfur reduction. It is suggested that together with the direct cracking of adsorbed thiophenic species on the additive, a further gasoline sulfur decrease is possible through cracking of saturated thiophenic species formed by hydrogenation of adsorbed thiophenic species with hydrogen produced in situ in the additive. The obtained results also demonstrate that solids with higher Lewis acidity are not unfailingly the most effective for gasoline sulfur reduction. (author)

Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering

KAUST Repository

Ruocco, N.

2016-05-27

We present a small angle neutron scattering (SANS) investigation of a blend composed of a dendritic polymer and a linear matrix with comparable viscosity in start-up of an elongational flow at Tg + 50. The two-generation dendritic polymer is diluted to 10% by weight in a matrix of a long well-entangled linear chains. Both components consist of mainly 1,4-cis-polyisoprene but differ in isotopic composition. The resulting scattering contrast is sufficiently high to permit time-resolved measurements of the system structure factor during the start-up phase and to follow the retraction processes involving the inner sections of the branched polymer in the nonlinear deformation response. The outer branches and the linear matrix, on the contrary, are in the linear deformation regime. The linear matrix dominates the rheological signature of the blend and the influence of the branched component can barely be detected. However, the neutron scattering intensity is predominantly that of the (branched) minority component so that its dynamics is clearly evident. In the present paper, we use the neutron scattering data to validate the branch point withdrawal process, which could not be unambiguously discerned from rheological measurements in this blend. The maximal tube stretch that the inner branches experience, before the relaxed outer arm material is incorporated into the tube is determined. The in situ scattering experiments demonstrate for the first time the leveling-off of the strain as the result of branch point withdrawal and chain retraction directly on the molecular level. We conclude that branch point motion in the mixture of architecturally complex polymers occurs earlier than would be expected in a purely branched system, presumably due to the different topological environment that the linear matrix presents to the hierarchically deep-buried tube sections. © 2016 American Chemical Society.

Branch Point Withdrawal in Elongational Startup Flow by Time-Resolved Small Angle Neutron Scattering

KAUST Repository

Ruocco, N.; Auhl, D.; Bailly, C.; Lindner, P.; Pyckhout-Hintzen, W.; Wischnewski, A.; Leal, L. G.; Hadjichristidis, Nikolaos; Richter, D.

2016-01-01

We present a small angle neutron scattering (SANS) investigation of a blend composed of a dendritic polymer and a linear matrix with comparable viscosity in start-up of an elongational flow at Tg + 50. The two-generation dendritic polymer is diluted to 10% by weight in a matrix of a long well-entangled linear chains. Both components consist of mainly 1,4-cis-polyisoprene but differ in isotopic composition. The resulting scattering contrast is sufficiently high to permit time-resolved measurements of the system structure factor during the start-up phase and to follow the retraction processes involving the inner sections of the branched polymer in the nonlinear deformation response. The outer branches and the linear matrix, on the contrary, are in the linear deformation regime. The linear matrix dominates the rheological signature of the blend and the influence of the branched component can barely be detected. However, the neutron scattering intensity is predominantly that of the (branched) minority component so that its dynamics is clearly evident. In the present paper, we use the neutron scattering data to validate the branch point withdrawal process, which could not be unambiguously discerned from rheological measurements in this blend. The maximal tube stretch that the inner branches experience, before the relaxed outer arm material is incorporated into the tube is determined. The in situ scattering experiments demonstrate for the first time the leveling-off of the strain as the result of branch point withdrawal and chain retraction directly on the molecular level. We conclude that branch point motion in the mixture of architecturally complex polymers occurs earlier than would be expected in a purely branched system, presumably due to the different topological environment that the linear matrix presents to the hierarchically deep-buried tube sections. © 2016 American Chemical Society.

Time- and energy resolved photoemission electron microscopy-imaging of photoelectron time-of-flight analysis by means of pulsed excitations

International Nuclear Information System (INIS)

Oelsner, Andreas; Rohmer, Martin; Schneider, Christian; Bayer, Daniela; Schoenhense, Gerd; Aeschlimann, Martin

2010-01-01

The present work enlightens the developments in time- and energy resolved photoemission electron microscopy over the past few years. We describe basic principles of the technique and demonstrate different applications. An energy- and time-filtering photoemission electron microscopy (PEEM) for real-time spectroscopic imaging can be realized either by a retarding field or hemispherical energy analyzer or by using time-of-flight optics with a delay line detector. The latter method has the advantage of no data loss at all as all randomly incoming particles are measured not only by position but also by time. This is of particular interest for pump-probe experiments in the femtosecond and attosecond time scale where space charge processes drastically limit the maximum number of photoemitted electrons per laser pulse. This work focuses particularly on time-of-flight analysis using a novel delay line detector. Time and energy resolved PEEM instruments with delay line detectors enable 4D imaging (x, y, Δt, E Kin ) on a true counting basis. This allows a broad range of applications from real-time observation of dynamic phenomena at surfaces to fs time-of-flight spectro-microscopy and even aberration correction. By now, these time-of-flight analysis instruments achieve intrinsic time resolutions of 108 ps absolute and 13.5 ps relative. Very high permanent measurement speeds of more than 4 million events per second in random detection regimes have been realized using a standard USB2.0 interface. By means of this performance, the time-resolved PEEM technique enables to display evolutions of spatially resolved (<25 nm) and temporal sliced images life on any modern computer. The method allows dynamics investigations of variable electrical, magnetic, and optical near fields at surfaces and great prospects in dynamical adaptive photoelectron optics. For dynamical processes in the ps time scale such as magnetic domain wall movements, the time resolution of the delay line detectors

Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas.

Science.gov (United States)

Liu, Lei; Deng, Leimin; Fan, Lisha; Huang, Xi; Lu, Yao; Shen, Xiaokang; Jiang, Lan; Silvain, Jean-François; Lu, Yongfeng

2017-10-30

Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al 2 O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al 2 O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O 2 chemistry in air.

Field instruments for real time in-situ crude oil concentration measurements

International Nuclear Information System (INIS)

Fuller, C.B.; Bonner, J.S.; Page, C.A.; Arrambide, G.; Sterling, M.C.Jr.; Ojo, T.O.

2003-01-01

Accidental oil spills, contaminant release during resuspension, storms, and harmful algal blooms are all episodic events that can effect coastal margins. It is important to quantitatively describe water and ecological quality evolution and predict the impact to these areas by such events, but traditional sampling methods miss environmental activity during cyclical events. This paper presents a new sampling approach that involves continuous, real-time in-situ monitoring to provide data for development of comprehensive modeling protocols. It gives spill response coordinators greater assurance in making decisions using the latest visualization tools which are based on a good understanding of the physical processes at work in pulsed events. Five sensors for rapid monitoring of crude oil concentrations in aquatic systems were described. The in-situ and ex-situ sensors can measure plume transport and estimate polycyclic aromatic hydrocarbon exposure concentrations to assess risk of toxicity. A brief description and evaluation of the following 5 sensors was provided: the LISST-100 by Sequoia Instrument, a submersible multi-angle laser scattering instrument; the AU-10 field fluorometer by Turner Designs, an ex-situ single wavelength fluorometer; the Flashlamp by WET Labs Inc., an in-situ single wavelength fluorometer; and, the ECO-FL3 and SAFire by WET Labs Inc., two in-situ multiple wavelength fluorometers. These instruments were used to analyze crude oil emissions of various concentrations. All of the instruments followed a linear response within the tested concentration range. At the lowest concentrations the LISST-100 was not as effective as the fluorometers because of limited particle volume for scatter. For the AU-10 field fluorometer, the highest concentrations tested were above the measurement range of the instrument. 6 refs., 5 figs

Nanosecond time-resolved EPR in pulse radiolysis via the spin echo method

International Nuclear Information System (INIS)

Trifunac, A.D.; Norris, J.R.; Lawler, R.G.

1979-01-01

The design and operation of a time-resolved electron spin echo spectrometer suitable for detecting transient radicals produced by 3 MeV electron radiolysis is described. Two modes of operation are available: Field swept mode which generates a normal EPR spectrum and kinetic mode in which the time dependence of a single EPR line is monitored. Techniques which may be used to minimize the effects of nonideal microwave pulses and overlapping sample tube signals are described. The principal advantages of the spin echo method over other time-resolved EPR methods are: (1) Improved time resolution (presently approx.30--50 nsec) allows monitoring of fast changes in EPR signals of transient radicals, (2) Lower susceptibility to interference between the EPR signal and the electron beam pulse at short times, and (3) Lack of dependence of transient signals on microwave field amplitude or static field inhomogeneity at short times. The performance of the instrument is illustrated using CIDEP from acetate radical formed in pulsed radiolysis of aqueous solutions of potassium acetate. The relaxation time and CIDEP enhancement factor obtained for this radical using the spin echo method compare favorably with previous determinations using direct detection EPR. Radical decay rates yield estimates of initial radical concentrations of 10 -4 10 -3 M per electron pulse. The Bloch equations are solved to give an expression for the echo signal for samples exhibiting CIDEP using arbitrary microwave pulse widths and distributions of Larmor frequencies. Conditions are discussed under which the time-dependent signal would be distorted by deviations from an ideal nonselective 90 0 --tau--180 0 pulse sequence

Noninvasive detection of inhomogeneities in turbid media with time-resolved log-slope analysis

International Nuclear Information System (INIS)

Wan, S.K.; Guo Zhixiong; Kumar, Sunil; Aber, Janice; Garetz, B.A.

2004-01-01

Detecting foreign objects embedded in turbid media using noninvasive optical tomography techniques is of great importance in many practical applications, such as in biomedical imaging and diagnosis, safety inspection on aircrafts and submarines, and LIDAR techniques. In this paper we develop a novel optical tomography approach based on slope analysis of time-resolved back-scattered signals collected at the medium boundaries where the light source is an ultrafast, short-pulse laser. As the optical field induced by the laser-pulse propagates, the detected temporal signals are influenced by the optical properties of the medium traversed. The detected temporal signatures therefore contain information that can indicate the presence of an inhomogeneity as well as its size and location relative to the laser source and detection systems. The log-slope analysis of the time-resolved back-scattered intensity is shown to be an effective method for extracting the information contained in the signal. The technique is validated by experimental results and by Monte Carlo simulations

Conditions for reliable time-resolved dosimetry of electronic portal imaging devices for fixed-gantry IMRT and VMAT

International Nuclear Information System (INIS)

Yeo, Inhwan Jason; Patyal, Baldev; Mandapaka, Anant; Jung, Jae Won; Yi, Byong Yong; Kim, Jong Oh

2013-01-01

Purpose: The continuous scanning mode of electronic portal imaging devices (EPID) that offers time-resolved information has been newly explored for verifying dynamic radiation deliveries. This study seeks to determine operating conditions (dose rate stability and time resolution) under which that mode can be used accurately for the time-resolved dosimetry of intensity-modulated radiation therapy (IMRT) beams.Methods: The authors have designed the following test beams with variable beam holdoffs and dose rate regulations: a 10 × 10 cm open beam to serve as a reference beam; a sliding window (SW) beam utilizing the motion of a pair of multileaf collimator (MLC) leaves outside the 10 × 10 cm jaw; a step and shoot (SS) beam to move the pair in step; a volumetric modulated arc therapy (VMAT) beam. The beams were designed in such a way that they all produce the same open beam output of 10 × 10 cm. Time-resolved ion chamber measurements at isocenter and time-resolved and integrating EPID measurements were performed for all beams. The time-resolved EPID measurements were evaluated through comparison with the ion chamber and integrating EPID measurements, as the latter are accepted procedures. For two-dimensional, time-resolved evaluation, a VMAT beam with an infield MLC travel was designed. Time-resolved EPID measurements and Monte Carlo calculations of such EPID dose images for this beam were performed and intercompared.Results: For IMRT beams (SW and SS), the authors found disagreement greater than 2%, caused by frame missing of the time-resolved mode. However, frame missing disappeared, yielding agreement better than 2%, when the dose rate of irradiation (and thus the frame acquisition rates) reached a stable and planned rate as the dose of irradiation was raised past certain thresholds (a minimum 12 s of irradiation per shoot used for SS IMRT). For VMAT, the authors found that dose rate does not affect the frame acquisition rate, thereby causing no frame missing

Influence of * OH adsorbates on the potentiodynamics of the CO 2 generation during the electro-oxidation of ethanol

Energy Technology Data Exchange (ETDEWEB)

Yang, Guangxing; Namin, Lida M.; Aaron Deskins, N.; Teng, Xiaowei

2017-09-01

Direct ethanol fuel cells (DEFCs) are a promising technology for the generation of electricity via the direct conversion of ethanol into CO2, showing higher thermodynamic efficiency and volumetric energy density than hydrogen fuel cells. However, implementation of DEFCs is hampered by the low CO2 selectivity during the ethanol oxidation reaction (EOR). Comprehensive understanding of the electro-kinetics and reaction pathways of CO2 generation via CC bond-breaking is not only a fundamental question for electro-catalysis, but also a key technological challenge since practical implementation of DEFC technology is contingent on its ability to selectively oxidize ethanol into CO2 to achieve exceptional energy density through 12-electron transfer reaction. Here, we present comprehensive in situ potentiodynamics studies of CO2 generation during the EOR on Pt, Pt/SnO2 and Pt/Rh/SnO2 catalysts using a house-made electrochemical cell equipped with a CO2 microelectrode. Highly sensitive CO2 measurements enable the real time detection of the partial pressure of CO2 during linear sweep voltammetry measurements, through which electro-kinetics details of CO2 generation can be obtained. In situ CO2 measurements provide the mechanistic understanding of potentiodynamics of the EOR, particularly the influence of *OH adsorbates on CO2 generation rate and selectivity. Density functional theory (DFT) simulations of Pt, Pt/SnO2, and Pt/Rh/SnO2 surfaces clarify reaction details over these catalysts. Our results show that at low potentials, inadequate *OH adsorbates impair the removal of reaction intermediates, and thus Pt/Rh/SnO2 exhibited the best performance toward CO2 generation, while at high potentials, Rh sites were overwhelmingly occupied (poisoned) by *OH adsorbates, and thus Pt/SnO2 exhibited the best performance toward CO2 generation.

Taking the pulse of snowmelt: in situ sensors reveal seasonal, event and diurnal patterns of nitrate and dissolved organic matter variability in an upland forest stream

Science.gov (United States)

Brian A. Pellerin; John Franco Saraceno; James B. Shanley; Stephen D. Sebestyen; George R. Aiken; Wilfred M. Wollheim; Brian A. Bergamaschi

2012-01-01

Highly resolved time series data are useful to accurately identify the timing, rate, and magnitude of solute transport in streams during hydrologically dynamic periods such as snowmelt. We used in situ optical sensors for nitrate (NO3-) and chromophoric dissolved organic matter fluorescence (FDOM) to measure surface water...

Denoising time-resolved microscopy image sequences with singular value thresholding

Energy Technology Data Exchange (ETDEWEB)

Furnival, Tom, E-mail: tjof2@cam.ac.uk; Leary, Rowan K., E-mail: rkl26@cam.ac.uk; Midgley, Paul A., E-mail: pam33@cam.ac.uk

2017-07-15

Time-resolved imaging in microscopy is important for the direct observation of a range of dynamic processes in both the physical and life sciences. However, the image sequences are often corrupted by noise, either as a result of high frame rates or a need to limit the radiation dose received by the sample. Here we exploit both spatial and temporal correlations using low-rank matrix recovery methods to denoise microscopy image sequences. We also make use of an unbiased risk estimator to address the issue of how much thresholding to apply in a robust and automated manner. The performance of the technique is demonstrated using simulated image sequences, as well as experimental scanning transmission electron microscopy data, where surface adatom motion and nanoparticle structural dynamics are recovered at rates of up to 32 frames per second. - Highlights: • Correlations in space and time are harnessed to denoise microscopy image sequences. • A robust estimator provides automated selection of the denoising parameter. • Motion tracking and automated noise estimation provides a versatile algorithm. • Application to time-resolved STEM enables study of atomic and nanoparticle dynamics.

Condition of granulating titanium-activated carbon composite adsorbent and its adsorption for uranium

International Nuclear Information System (INIS)

Miyai, Yoshitaka; Kitamura, Takao; Katoh, Shunsaku; Miyazaki, Hidetoshi

1979-01-01

The powdery titanium-activated carbon composite adsorbent was granulated, and the strength and uranium adsorptivity of the granulated adsorbent were studied in relation to its granulating condition. By use of polyvinylalcohol (PVA) with degree of polymerization above 2,000 as binder, the granular adsorbent with as much the same strength as commercial granular activated carbon was obtained. Addition of PVA did not affect the amount of adsorbed uranium in equilibrium, but decreased the adsorption rate. Effect of granule size between 2-5 mm on the uranium adsorption rate was that the uranium adsorption rate changed proportionally to surface area of assumed sphere. As a test for practical use, 5 times repetitions of adsorption and desorption were carried out on the same granular adsorbent. During this repetition the adsorbent containing formalized PVA revealed smaller weight loss than non-treated adsorbent. The amount of adsorbed uranium decreased with increasing repetition times, and reason of this was discussed. (author)

In situ detection of warfarin using time-correlated single-photon counting

Energy Technology Data Exchange (ETDEWEB)

Rosengren, Annika M.; Karlsson, Bjoern C.G. [Bioorganic and Biophysical Chemistry Laboratory, School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar (Sweden); Naeslund, Inga; Andersson, Per Ola [Swedish Defence Research Agency, FOI, CBRN Defence and Security, SE-901 82 Umea (Sweden); Nicholls, Ian A., E-mail: ian.a.nicholls@bioorg.uu.se [Bioorganic and Biophysical Chemistry Laboratory, School of Natural Sciences, Linnaeus University, SE-391 82 Kalmar (Sweden); Department of Biochemistry and Organic Chemistry Laboratory, Uppsala University, SE-751 23 Uppsala (Sweden)

2011-04-01

Highlights: {yields} Direct in situ measurement of specific isomeric forms of the anticoagulant warfarin. {yields} TCSPC spectroscopy in conjunction with synthetic Sudlow I binding site receptors. {yields} Development of sensor principle for use in clinical and environmental monitoring. -- Abstract: Here we report on a novel method for the direct in situ measurement of specific isomeric forms of the anticoagulant warfarin using time correlated single-photon counting (TCSPC) spectroscopy in conjunction with synthetic Sudlow I binding site receptors. The method is highly robust over the clinically significant concentration range, and demonstrates the potential of the binding site mimics in conjunction with the spectroscopic strategy employed here for the determination of this important pharmaceutical in clinical or even environmental samples.

In situ detection of warfarin using time-correlated single-photon counting

International Nuclear Information System (INIS)

Rosengren, Annika M.; Karlsson, Bjoern C.G.; Naeslund, Inga; Andersson, Per Ola; Nicholls, Ian A.

2011-01-01

Highlights: → Direct in situ measurement of specific isomeric forms of the anticoagulant warfarin. → TCSPC spectroscopy in conjunction with synthetic Sudlow I binding site receptors. → Development of sensor principle for use in clinical and environmental monitoring. -- Abstract: Here we report on a novel method for the direct in situ measurement of specific isomeric forms of the anticoagulant warfarin using time correlated single-photon counting (TCSPC) spectroscopy in conjunction with synthetic Sudlow I binding site receptors. The method is highly robust over the clinically significant concentration range, and demonstrates the potential of the binding site mimics in conjunction with the spectroscopic strategy employed here for the determination of this important pharmaceutical in clinical or even environmental samples.

Time resolved Thomson scattering diagnostic of pulsed gas metal arc welding (GMAW) process

International Nuclear Information System (INIS)

Kühn-Kauffeldt, M; Schein, J; Marquès, J L

2014-01-01

In this work a Thomson scattering diagnostic technique was applied to obtain time resolved electron temperature and density values during a gas metal arc welding (GMAW) process. The investigated GMAW process was run with aluminum wire (AlMg 4,5 Mn) with 1.2 mm diameter as a wire electrode, argon as a shielding gas and peak currents in the range of 400 A. Time resolved measurements could be achieved by triggering the laser pulse at shifted time positions with respect to the current pulse driving the process. Time evaluation of resulting electron temperatures and densities is used to investigate the state of the plasma in different phases of the current pulse and to determine the influence of the metal vapor and droplets on the plasma properties

Generation of pulsed far-infrared radiation and its application for far-infrared time-resolved spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kondo, Yasuhiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1996-07-01

So-called time-resolved spectroscopy technique has been used from old time as the means for studying the dynamic optical property, light-induced reaction and so on of matters. As an example, there is the method called pump and probe, and here, the wavelength of this probe light is the problem. If the object energy region is limited to about 0.1 eV, fast time-resolved spectroscopy is feasible relatively easily. However, energy region is extended to low energy region, the light source which is available as the pulsed probe light having sufficient intensity is limited. In this paper, the attempt of time-resolved spectroscopy utilizing coherent radiation, which has ended in failure, and the laser pulse-induced far-infrared radiation which can be utilized as new far-infrared probe light are reported. The reason why far-infrared radiation is used is explained. The attempt of time-resolved spectroscopy using NaCl crystals is reported on the equipment, the method of measuring absorption spectra and the results. Laser pulse-induced far-infrared radiation and the method of generating it are described. The multi-channel detector for far-infrared radiation which was made for trial is shown. (K.I.)

Time Resolved Detection of Infrared Synchrotron Radiation at DAΦNE

International Nuclear Information System (INIS)

Bocci, A.; Marcelli, A.; Drago, A.; Guidi, M. Cestelli; Pace, E.; Piccinini, M.; Sali, D.; Morini, P.; Piotrowski, J.

2007-01-01

Synchrotron radiation is characterized by a very wide spectral emission from IR to X-ray wavelengths and a pulsed structure that is a function of the source time structure. In a storage ring, the typical temporal distance between two bunches, whose duration is a few hundreds of picoseconds, is on the nanosecond scale. Therefore, synchrotron radiation sources are a very powerful tools to perform time-resolved experiments that however need extremely fast detectors. Uncooled IR devices optimized for the mid-IR range with sub-nanosecond response time, are now available and can be used for fast detection of intense IR sources such as synchrotron radiation storage rings. We present here different measurements of the pulsed synchrotron radiation emission at DAΦNE (Double Annular Φ-factory for Nice Experiments), the collider of the Laboratori Nazionali of Frascati (LNF) of the Istituto Nazionale di Fisica Nucleare (INFN), performed with very fast uncooled infrared detectors with a time resolution of a few hundreds of picoseconds. We resolved the emission time structure of the electron bunches of the DAΦNE collider when it works in a normal condition for high energy physics experiments with both photovoltaic and photoconductive detectors. Such a technology should pave the way to new diagnostic methods in storage rings, monitoring also source instabilities and bunch dynamics

Time-resolved methods in biophysics. 6. Time-resolved Laue crystallography as a tool to investigate photo-activated protein dynamics.

Science.gov (United States)

Bourgeois, Dominique; Schotte, Friedrich; Brunori, Maurizio; Vallone, Beatrice

2007-10-01

When polychromatic X-rays are shined onto crystalline material, they generate a Laue diffraction pattern. At third generation synchrotron radiation sources, a single X-ray pulse of approximately 100 ps duration is enough to produce interpretable Laue data from biomolecular crystals. Thus, by initiating biological turnover in a crystalline protein, structural changes along the reaction pathway may be filmed by ultra-fast Laue diffraction. Using laser-light as a trigger, transient species in photosensitive macromolecules can be captured at near atomic resolution with sub-nanosecond time-resolution. Such pump-probe Laue experiments have now reached an outstanding level of sophistication and have found a domain of excellence in the investigation of light-sensitive proteins undergoing cyclic photo-reactions and producing stiff crystals. The main theoretical concepts of Laue diffraction and the challenges associated with time-resolved experiments on biological crystals are recalled. The recent advances in the design of experiments are presented in terms of instrumental choices, data collection strategy and data processing, and some of the inherent difficulties of the method are highlighted. The discussion is based on the example of myoglobin, a protein that has traversed the whole history of pump-probe Laue diffraction, and for which a massive amount of data have provided considerable insight into the understanding of protein dynamics.

Rapid on-site sensing aflatoxin B1 in food and feed via a chromatographic time-resolved fluoroimmunoassay.

Directory of Open Access Journals (Sweden)

Zhaowei Zhang

Full Text Available Aflatoxin B1 poses grave threats to food and feed safety due to its strong carcinogenesis and toxicity, thus requiring ultrasensitive rapid on-site determination. Herein, a portable immunosensor based on chromatographic time-resolved fluoroimmunoassay was developed for sensitive and on-site determination of aflatoxin B1 in food and feed samples. Chromatographic time-resolved fluoroimmunoassay offered a magnified positive signal and low signal-to-noise ratio in time-resolved mode due to the absence of noise interference caused by excitation light sources. Compared with the immunosensing performance in previous studies, this platform demonstrated a wider dynamic range of 0.2-60 μg/kg, lower limit of detection from 0.06 to 0.12 µg/kg, and considerable recovery from 80.5% to 116.7% for different food and feed sample matrices. It was found to be little cross-reactivity with other aflatoxins (B2, G1, G2, and M1. In the case of determination of aflatoxin B1 in peanuts, corn, soy sauce, vegetable oil, and mouse feed, excellent agreement was found when compared with aflatoxin B1 determination via the conversational high-performance liquid chromatography method. The chromatographic time-resolved fluoroimmunoassay affords a powerful alternative for rapid on-site determination of aflatoxin B1 and holds a promise for food safety in consideration of practical food safety and environmental monitoring.

Rapid on-site sensing aflatoxin B1 in food and feed via a chromatographic time-resolved fluoroimmunoassay.

Science.gov (United States)

Zhang, Zhaowei; Tang, Xiaoqian; Wang, Du; Zhang, Qi; Li, Peiwu; Ding, Xiaoxia

2015-01-01

Aflatoxin B1 poses grave threats to food and feed safety due to its strong carcinogenesis and toxicity, thus requiring ultrasensitive rapid on-site determination. Herein, a portable immunosensor based on chromatographic time-resolved fluoroimmunoassay was developed for sensitive and on-site determination of aflatoxin B1 in food and feed samples. Chromatographic time-resolved fluoroimmunoassay offered a magnified positive signal and low signal-to-noise ratio in time-resolved mode due to the absence of noise interference caused by excitation light sources. Compared with the immunosensing performance in previous studies, this platform demonstrated a wider dynamic range of 0.2-60 μg/kg, lower limit of detection from 0.06 to 0.12 µg/kg, and considerable recovery from 80.5% to 116.7% for different food and feed sample matrices. It was found to be little cross-reactivity with other aflatoxins (B2, G1, G2, and M1). In the case of determination of aflatoxin B1 in peanuts, corn, soy sauce, vegetable oil, and mouse feed, excellent agreement was found when compared with aflatoxin B1 determination via the conversational high-performance liquid chromatography method. The chromatographic time-resolved fluoroimmunoassay affords a powerful alternative for rapid on-site determination of aflatoxin B1 and holds a promise for food safety in consideration of practical food safety and environmental monitoring.

Mesoporous silica/polyacrylamide composite: Preparation by UV-graft photopolymerization, characterization and use as Hg(II) adsorbent

Energy Technology Data Exchange (ETDEWEB)

Saad, Ali, E-mail: ali.saad8803@gmail.com [Laboratory of Materials, Molecules and Applications, IPEST, University of Carthage, Sidi Bou Said road, B.P. 51, 2070 La Marsa (Tunisia); Faculté des Sciences de Tunis, Université El Manar, PO Box 248, El Manar II, 2092 Tunis (Tunisia); Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Bakas, Idriss [Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Laboratoire AQUAMAR, Equipe Matériaux Photocatalyse et Environnement, Faculté des Sciences, Université Ibn Zohr, B.P. 8106, Cité Dakhla, Agadir (Morocco); Piquemal, Jean-Yves; Nowak, Sophie [Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Abderrabba, Manef, E-mail: abderrabbamanef@gmail.com [Laboratory of Materials, Molecules and Applications, IPEST, University of Carthage, Sidi Bou Said road, B.P. 51, 2070 La Marsa (Tunisia); Chehimi, Mohamed M., E-mail: chehimi@icmpe.cnrs.fr [Univ Paris Diderot, Sorbonne Paris Cité, ITODYS, UMR 7086, CNRS, F-75013 Paris (France); Université Paris Est, ICMPE (UMR7182), CNRS, UPEC, F-94320 Thiais (France)

2016-03-30

Graphical abstract: - Highlights: • Mesoporous silica/polyacrylamide nanocomposite adsorbent was prepared by UV-graft polymerization. • Polyacrylamide was successfully grafted onto the silanized mesoporous silica. • The Hg(II) adsorption capacity of the nanocomposite was as high as 177 mg g{sup −1} after 1 h at RT. • Adsorption process was found to fit pseudo second order kinetics and exothermic. - Abstract: MCM-41 ordered mesoporous silica was prepared, aminosilanized and grafted with polyacrylamide (PAAM) through in situ radical photopolymerization process. The resulting composite, denoted PAAM-NH{sub 2}-MCM-41, the calcined and silanized reference MCM-41s were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N{sub 2} physisorption at 77 K. These complementary techniques brought strong supporting evidence for the silanization process followed by PAAM grafting. The surface composition was found to be PAAM-rich as judged by XPS. The composite was then employed for the uptake of Hg(II) from aqueous solutions. Adsorption was monitored versus pH, time, and temperature. The maximum adsorption capacity at 25 °C and pH 5.2 was 177 mg g{sup −1}. Kinetically, the equilibrium was reached within 60 min for a 100 mg L{sup −1} mercury solution. The adsorption of Hg(II) on PAAM-NH{sub 2}-MCM-41 composites followed second order kinetics. Thermodynamic parameters suggested that the favorable adsorption process is exothermic in nature and the adsorption is ascribed to a decrease in the degree of freedom of adsorbed ions which results in the entropy change. This work conclusively shows that mesoporous silica–polymer hybrid metal ion adsorbents (with robust silica–polymer interface) can be prepared in a simple way by in situ radical photopolymerization in the presence of

Investigations Into the Reusability of Amidoxime-Based Polymeric Uranium Adsorbents

Energy Technology Data Exchange (ETDEWEB)

Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Wai, Chien M. [Univ. of Idaho, Moscow, ID (United States); LCW Supercritical Technologies, Seattle, WA (United States); Pan, H. B. [Univ. of Idaho, Moscow, ID (United States)

2016-09-28

Significant advancements in amidoxime-based polymeric adsorbents to extract uranium from seawater are achieved in recent years. The success of uranium adsorbent development can help provide a sustainable supply of fuel for nuclear reactors. To bring down the production cost of this new technology, in addition to the development of novel adsorbents with high uranium capacity and manufacture cost, the development of adsorbent re-using technique is critical because it can further reduce the cost of the adsorbent manufacture. In our last report, the use of high concentrations of bicarbonate solution (3M KHCO3) was identified as a cost-effective, environmental friendly method to strip uranium from amidoxime-based polymeric adsorbents. This study aims to further improve the method for high recovery of uranium capacity in re-uses and to evaluate the performance of adsorbents after multiple re-use cycles. Adsorption of dissolved organic matter (DOM) on the uranium adsorbents during seawater exposure can hinder the uranium adsorption and slow down the adsorption rate. An additional NaOH rinse (0.5 M NaOH, room temperature) was applied after the 3 M KHCO3 elution to remove natural organic matter from adsorbents. The combination of 3 M KHCO3 elution and 0.5 M NaOH rinse significantly improves the recovery of uranium adsorption capacity in the re-used adsorbents. In the first re-use, most ORNL adsorbents tested achieve ~100% recovery by using 3 M KHCO3 elution + 0.5 M NaOH rinse approach, in comparison to 54% recovery when only 3 M KHCO3 elution was applied. A significant drop in capacity was observed when the adsorbents went through more than one re-use. FTIR spectra revealed that degradation of amidoxime ligands occurs during seawater exposure, and is more significant the longer the exposure time. Significantly elevated ratios of Ca/U and Mg/U in re-used adsorbents support the decrease in abundance of amidoxime ligands and increase carboxylate group from FT-IR analysis. The

Time resolved fluorescence of cow and goat milk powder

Science.gov (United States)

Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

2017-01-01

Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

Time-resolved magnetization dynamics of cross-tie domain walls in permalloy microstructures

International Nuclear Information System (INIS)

Miguel, J; Kurde, J; Piantek, M; Kuch, W; Sanchez-Barriga, J; Heitkamp, B; Kronast, F; Duerr, H A; Bayer, D; Aeschlimann, M

2009-01-01

We report on a picosecond time-resolved x-ray magnetic circular dichroic-photoelectron emission microscopy study of the evolution of the magnetization components of a microstructured permalloy platelet comprising three cross-tie domain walls. A laser-excited photoswitch has been used to apply a triangular 80 Oe, 160 ps magnetic pulse. Micromagnetic calculations agree well with the experimental results, both in time and frequency, illustrating the large angle precession in the magnetic domains with magnetization perpendicular to the applied pulse, and showing how the magnetic vortices revert their core magnetization while the antivortices remain unaffected.

Time-resolved magnetization dynamics of cross-tie domain walls in permalloy microstructures

Energy Technology Data Exchange (ETDEWEB)

Miguel, J; Kurde, J; Piantek, M; Kuch, W [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin (Germany); Sanchez-Barriga, J; Heitkamp, B; Kronast, F; Duerr, H A [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Bayer, D; Aeschlimann, M, E-mail: jorge.miguel@fu-berlin.d [Fachbereich Physik, Universitaet Kaiserslautern, Erwin-Schroedinger Strasse 46, D-67663 Kaiserslautern (Germany)

2009-12-02

We report on a picosecond time-resolved x-ray magnetic circular dichroic-photoelectron emission microscopy study of the evolution of the magnetization components of a microstructured permalloy platelet comprising three cross-tie domain walls. A laser-excited photoswitch has been used to apply a triangular 80 Oe, 160 ps magnetic pulse. Micromagnetic calculations agree well with the experimental results, both in time and frequency, illustrating the large angle precession in the magnetic domains with magnetization perpendicular to the applied pulse, and showing how the magnetic vortices revert their core magnetization while the antivortices remain unaffected.

Time-resolved magnetic imaging in an aberration-corrected, energy-filtered photoemission electron microscope

International Nuclear Information System (INIS)

Nickel, F.; Gottlob, D.M.; Krug, I.P.; Doganay, H.; Cramm, S.; Kaiser, A.M.; Lin, G.; Makarov, D.; Schmidt, O.G.

2013-01-01

We report on the implementation and usage of a synchrotron-based time-resolving operation mode in an aberration-corrected, energy-filtered photoemission electron microscope. The setup consists of a new type of sample holder, which enables fast magnetization reversal of the sample by sub-ns pulses of up to 10 mT. Within the sample holder current pulses are generated by a fast avalanche photo diode and transformed into magnetic fields by means of a microstrip line. For more efficient use of the synchrotron time structure, we developed an electrostatic deflection gating mechanism capable of beam blanking within a few nanoseconds. This allows us to operate the setup in the hybrid bunch mode of the storage ring facility, selecting one or several bright singular light pulses which are temporally well-separated from the normal high-intensity multibunch pulse pattern. - Highlights: • A new time-resolving operation mode in photoemission electron microscopy is shown. • Our setup works within an energy-filtered, aberration-corrected PEEM. • A new gating system for bunch selection using synchrotron radiation is developed. • An alternative magnetic excitation system is developed. • First tr-imaging using an energy-filtered, aberration-corrected PEEM is shown

Experimental Evaluation Use of Semifluidized Bed Adsorber for the Treatment of P-chlorophenol and O-cresol in Wastewater using Activated Carbon as Adsorbent

Directory of Open Access Journals (Sweden)

Saad Hanash Ammar

2015-12-01

Full Text Available In the present work the performance of semifluidized bed adsorber was evaluated for removal of phenolic compound from wastewater using commercial activated carbon as adsorbent. P-chlorophenol (4-Chlorophenol and o-cresol (2-methylphenol was selected as a phenolic compound for that purpose. The phenols percent removal, in term of breakthrough curves were studied as affected by hydrodynamics limitations which include minimum and maximum semifluidization velocities and packed bed formation in the column by varying various parameters such as inlet liquid superficial velocity (from Uminsf to 8Uminsf m/s, and retaining grid (sometimes referred to as adsorbent loading to initial static bed height ratio (from 3-4.5. Inlet phenols concentration (50-400 mg/l and initial pH of the liquid solutions feed (from 4 to 10 were also studied. The experimental semifluidized adsorber unit was designed and constructed in Chem. Eng. labs at Al-Nahrain University (consisted of a QVF glass tube 2.54 cm inside diameter, and 70cm length. The results showed that the initial percent removal of phenolic compounds (P-chlorophenol and o-cresol decrease with increasing the superficial liquid velocity while the time required reaching equilibrium state decreased. Also it slightly affected with the increase in the retaining grid height and the time required to reach the equilibrium value decreased.

Time-resolved x-ray absorption spectroscopy: Watching atoms dance

Science.gov (United States)

Milne, Chris J.; Pham, Van-Thai; Gawelda, Wojciech; van der Veen, Renske M.; El Nahhas, Amal; Johnson, Steven L.; Beaud, Paul; Ingold, Gerhard; Lima, Frederico; Vithanage, Dimali A.; Benfatto, Maurizio; Grolimund, Daniel; Borca, Camelia; Kaiser, Maik; Hauser, Andreas; Abela, Rafael; Bressler, Christian; Chergui, Majed

2009-11-01

The introduction of pump-probe techniques to the field of x-ray absorption spectroscopy (XAS) has allowed the monitoring of both structural and electronic dynamics of disordered systems in the condensed phase with unprecedented accuracy, both in time and in space. We present results on the electronically excited high-spin state structure of an Fe(II) molecular species, [FeII(bpy)3]2+, in aqueous solution, resolving the Fe-N bond distance elongation as 0.2 Å. In addition an analysis technique using the reduced χ2 goodness of fit between FEFF EXAFS simulations and the experimental transient absorption signal in energy space has been successfully tested as a function of excited state population and chemical shift, demonstrating its applicability in situations where the fractional excited state population cannot be determined through other measurements. Finally by using a novel ultrafast hard x-ray 'slicing' source the question of how the molecule relaxes after optical excitation has been successfully resolved using femtosecond XANES.

Monitoring dynamic electrochemical processes with in situ ptychography

Science.gov (United States)

Kourousias, George; Bozzini, Benedetto; Jones, Michael W. M.; Van Riessen, Grant A.; Dal Zilio, Simone; Billè, Fulvio; Kiskinova, Maya; Gianoncelli, Alessandra

2018-03-01

The present work reports novel soft X-ray Fresnel CDI ptychography results, demonstrating the potential of this method for dynamic in situ studies. Specifically, in situ ptychography experiments explored the electrochemical fabrication of Co-doped Mn-oxide/polypyrrole nanocomposites for sustainable and cost-effective fuel-cell air-electrodes. Oxygen-reduction catalysts based on Mn-oxides exhibit relatively high activity, but poor durability: doping with Co has been shown to improve both reduction rate and stability. In this study, we examine the chemical state distribution of the catalytically crucial Co dopant to elucidate details of the Co dopant incorporation into the Mn/polymer matrix. The measurements were performed using a custom-made three-electrode thin-layer microcell, developed at the TwinMic beamline of Elettra Synchrotron during a series of experiments that were continued at the SXRI beamline of the Australian Synchrotron. Our time-resolved ptychography-based investigation was carried out in situ after two representative growth steps, controlled by electrochemical bias. In addition to the observation of morphological changes, we retrieved the spectroscopic information, provided by multiple ptychographic energy scans across Co L3-edge, shedding light on the doping mechanism and demonstrating a general approach for the molecular-level investigation complex multimaterial electrodeposition processes.

Motion of Adsorbed Nano-Particles on Azobenzene Containing Polymer Films

Directory of Open Access Journals (Sweden)

Sarah Loebner

2016-12-01

Full Text Available We demonstrate in situ recorded motion of nano-objects adsorbed on a photosensitive polymer film. The motion is induced by a mass transport of the underlying photoresponsive polymer material occurring during irradiation with interference pattern. The polymer film contains azobenzene molecules that undergo reversible photoisomerization reaction from trans- to cis-conformation. Through a multi-scale chain of physico-chemical processes, this finally results in the macro-deformations of the film due to the changing elastic properties of polymer. The topographical deformation of the polymer surface is sensitive to a local distribution of the electrical field vector that allows for the generation of dynamic changes in the surface topography during irradiation with different light interference patterns. Polymer film deformation together with the motion of the adsorbed nano-particles are recorded using a homemade set-up combining an optical part for the generation of interference patterns and an atomic force microscope for acquiring the surface deformation. The particles undergo either translational or rotational motion. The direction of particle motion is towards the topography minima and opposite to the mass transport within the polymer film. The ability to relocate particles by photo-induced dynamic topography fluctuation offers a way for a non-contact simultaneous manipulation of a large number of adsorbed particles just in air at ambient conditions.

Time-resolved MR angiography of the renal artery: morphology and perfusion

International Nuclear Information System (INIS)

Krause, U.J.; Pabst, T.; Koestler, H.; Helbig, C.; Kenn, W.; Hahn, D.

2002-01-01

Purpose: To prove the hypothesis that renal artery stenosis and changes in renal perfusion can be detected with contrast-enhanced time-resolved MR angiography in a single examination. Material and Methods: In 71 patients, 137 renal arteries and 14 accessory renal arteries were studied. The examinations were performed on a 1.5 T system. A T 1 -weighted gradient echo sequence with a temporal resolution of 7 s was used. Single dose of contrast material (0.1 mmol/kg Gd-DTPA) was injected with a power injector with a flow rate of 2 ml/s. Criterion for the assessment of renal perfusion was the slope ratio of the signal intensity time curve in both kidneys. Results: Forty renal artery stenoses and one occlusion of a renal artery were detected. In 48 kidneys (35%) segmental arteries were evaluated. The accuracy of the slope ratio (limit value 0.75) concerning the detection of unilateral renal artery stenosis was 92.6% (sensitivity 75%, specificity 95.7%). Conclusion: Time-resolved MR angiography can detect changes in renal perfusion in patients with unilateral renal artery stenosis. (orig.) [de

Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

Energy Technology Data Exchange (ETDEWEB)

Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL

2014-04-30

ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

Time resolved measurements of cathode fall in high frequency fluorescent lamps

International Nuclear Information System (INIS)

Hadrath, S; Garner, R C; Lieder, G H; Ehlbeck, J

2007-01-01

Measurements are presented of the time resolved cathode and anode falls of high frequency fluorescent lamps for a range of discharge currents typically encountered in dimming mode. Measurements were performed with the movable anode technique. Supporting spectroscopic emission measurements were made of key transitions (argon 420.1 nm and mercury 435.8 nm), whose onset coincide with cathode fall equalling the value associated with the energy, relative to the ground state, of the upper level of the respective transition. The measurements are in general agreement with the well-known understanding of dimmed lamp operation: peak cathode fall decreases with increasing lamp current and with increasing auxiliary coil heating. However, the time dependence of the measurements offers additional insight

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

International Nuclear Information System (INIS)

Gill, Gary A.; Das, Sadananda; Mayes, Richard; Saito, Tomonori; Brown, Suree S.; Tsouris, Constantinos; Tsouris, Costas; Wai, Chien M.; Pan, Horng-Bin

2016-01-01

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL's Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL's Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980's (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a 180

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Sciences Lab.; Janke, Christopher J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, Sadananda [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Saito, Tomonori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Brown, Suree S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tsouris, Constantinos [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wai, Chien M. [Univ. of Idaho, Moscow, ID (United States); LCW Supercritical Technologies, Seattle, WA (United States); Pan, Horng-Bin [Univ. of Idaho, Moscow, ID (United States)

2016-09-29

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includes other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U/kg adsorbent for a

In situ remediation of uranium contaminated groundwater

International Nuclear Information System (INIS)

Dwyer, B.P.; Marozas, D.C.

1997-01-01

In an effort to develop cost-efficient techniques for remediating uranium contaminated groundwater at DOE Uranium Mill Tailing Remedial Action (UMTRA) sites nationwide, Sandia National Laboratories (SNL) deployed a pilot scale research project at an UMTRA site in Durango, CO. Implementation included design, construction, and subsequent monitoring of an in situ passive reactive barrier to remove Uranium from the tailings pile effluent. A reactive subsurface barrier is produced by emplacing a reactant material (in this experiment various forms of metallic iron) in the flow path of the contaminated groundwater. Conceptually the iron media reduces and/or adsorbs uranium in situ to acceptable regulatory levels. In addition, other metals such as Se, Mo, and As have been removed by the reductive/adsorptive process. The primary objective of the experiment was to eliminate the need for surface treatment of tailing pile effluent. Experimental design, and laboratory and field results are discussed with regard to other potential contaminated groundwater treatment applications

Krypton retention on solid adsorbents

International Nuclear Information System (INIS)

Monson, P.R. Jr.

1981-08-01

Over a dozen prospective adsorbents for krypton were studied and evaluated with respect to adsorption capacity and cost for dissolver off-gas streams from nuclear reprocessing plants. Results show that, at subambient temperature (-40 0 to -80 0 C), the commercially available hydrogen mordenite has sufficient adsorptive capacity to be the most cost-effective material studied. Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite. The results indicate that a solid adsorbent system is feasible and competitive with other developing systems whih utilize fluorocarbon absorption and cryogenic distillation

In Situ STM and AFM of the Copper Protein Pseudomonas Aeruginosa Azurin

DEFF Research Database (Denmark)

Friis, Esben P.; Andersen, Jens Enevold Thaulov; Madsen, L.L.

1997-01-01

to gold and facile electron tunnel routes between this group and the copper atom. Azurin adsorbed on Au(111) can be imaged to molecular resolution by in situ STM and shows regular arrays of individual structures corresponding well to the known molecular size of azurin. The current falls off approximately...... exponentially with increasing distance with a decay constant of 0.4–0.5 Å−1. In comparison in situ AFM shows structures laterally convoluted with the tip while the vertical extension is in the same range as the structural size of azurin. The results are of interest in relation to electron tunnel mechanisms...

A review of the analysis of complex time-resolved fluorescence anisotropy data

International Nuclear Information System (INIS)

Smith, Trevor A; Ghiggino, Kenneth P

2015-01-01

Time-resolved fluorescence anisotropy measurements (TRAMs) are widely used to probe the dynamics of the various processes that can lead to the depolarisation of emission following photoselection by polarised excitation. The most commonly investigated of these emission depolarising phenomena is molecular rotational motion, but TRAMs are very useful for determining the kinetics of a host of other processes. In this paper we review several examples for which we have observed in our laboratories initially unexpectedly complex temporal behaviour of the time-resolved fluorescence anisotropy signal from relatively ‘simple’ chemical systems. In certain circumstances the anisotropy (i) decays on timescales when superficially it might be thought it should remain constant, (ii) shows marked ‘dip and rise’ behaviour in its intensity, or (iii) can change sign as the anisotropy evolves in time. Fundamentally simple processes, including molecular rotational motion, energy migration and excited state photophysics, can cause such behaviour. (topical review)

Removal of Copper(II) Ions in Aqueous Solutions Using Tannin-Rich Plants as Natural Bio-Adsorbents

Science.gov (United States)

Paksamut, J.; Boonsong, P.

2018-03-01

In this study, the purpose of our interest is to investigatethe adsorption behavior of copper (II) ions in aqueous solution using some tannin-rich plants as natural bio-adsorbents such as mangosteen peels (Garciniamangostana L.), cassava leaves (Manihotesculenta Crantz) and Thai copper pod leaves (Sennasiamea (Lam.)) as powder form in different dosage of adsorbent plant materials.The adsorption capacities at different pH of solution and contact time were performed.All the experiments in this studywere chosen at room temperature by batch technique. From the experimental results showed that cassava leaves gave better adsorbent properties than mangosteen peels and Thai copper pod leaves. The increasing dosage of all adsorbents and contact time have been found to increase adsorption capacities. In this respect, the adsorption capacities depend crucially on the adsorbents and contact time. The optimum pH of copper (II) ions adsorption was pH4. According to this work, it was observed that bioadsorbent materials from tannin-rich plants could be used to remove copper (II) ions from aqueous solutions.

Adsorbate-induced modification of electronic band structure of epitaxial Bi(111) films

Energy Technology Data Exchange (ETDEWEB)

Matetskiy, A.V., E-mail: mateckij@iacp.dvo.ru [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Bondarenko, L.V.; Tupchaya, A.Y.; Gruznev, D.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); Eremeev, S.V. [Institute of Strength Physics and Materials Science, 634021 Tomsk (Russian Federation); Tomsk State University, 634050 Tomsk (Russian Federation); Zotov, A.V. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Department of Electronics, Vladivostok State University of Economics and Service, 690600 Vladivostok (Russian Federation); Saranin, A.A. [Institute of Automation and Control Processes FEB RAS, 5 Radio Street, 690041 Vladivostok (Russian Federation); School of Natural Sciences, Far Eastern Federal University, 690950 Vladivostok (Russian Federation)

2017-06-01

Highlights: • Modification of electronic properties of ultrathin Bi films by adsorbates is demonstrated. • Due to electron doping from Cs adatoms, surface-state bands shift to higher binding energies. • As a result, only electron pockets are left in the Fermi map. • Tin acts as an acceptor dopant for Bi, shifting Fermi level upward. • As a result, only hole pockets are left in the Fermi map. - Abstract: Changes of the electronic band structure of Bi(111) films on Si(111) induced by Cs and Sn adsorption have been studied using angle-resolved photoemission spectroscopy and density functional theory calculations. It has been found that small amounts of Cs when it presents at the surface in a form of the adatom gas leads to shifting of the surface and quantum well states to the higher binding energies due to the electron donation from adsorbate to the Bi film. In contrast, adsorbed Sn dissolves into the Bi film bulk upon heating and acts as an acceptor dopant, that results in shifting of the surface and quantum well states upward to the lower binding energies. These results pave the way to manipulate with the Bi thin film electron band structure allowing to achieve a certain type of conductivity (electron or hole) with a single spin channel at the Fermi level making the adsorbate-modified Bi a reliable base for prospective spintronics applications.

Femtosecond time-resolved vibrational SFG spectroscopy of CO/Ru( 0 0 1 )

Science.gov (United States)

Hess, Ch.; Wolf, M.; Roke, S.; Bonn, M.

2002-04-01

Vibrational sum-frequency generation (SFG) employing femtosecond infrared (IR) laser pulses is used to study the dynamics of the C-O stretch vibration on Ru(0 0 1). Time-resolved measurements of the free induction decay (FID) of the IR-polarization for 0.33 ML CO/Ru(0 0 1) exhibit single exponential decays over three decades corresponding to dephasing times of T2=1.94 ps at 95 K and T2=1.16 ps at 340 K. This is consistent with pure homogeneous broadening due to anharmonic coupling with the thermally activated low-frequency dephasing mode together with a contribution from saturation of the IR transition. In pump-probe SFG experiments using a strong visible (VIS) pump pulse the perturbation of the FID leads to transient line shifts even at negative delay times, i.e. when the IR-VIS SFG probe pair precedes the pump pulse. Based on an analysis of the time-dependent polarization we discuss the influence of the perturbed FID on time-resolved SFG spectra. We investigate how coherent effects affect the SFG spectra and we examine the time resolution in these experiments, in particular in dependence of the dephasing time.

The TimBel synchronization board for time resolved experiments at synchrotron SOLEIL

International Nuclear Information System (INIS)

Ricaud, J.P.; Betinelli-Deck, P.; Bisou, J.; Elattaoui, X.; Laulhe, C.; Monteiro, P.; Nadolski, L.S.; Renaud, G.; Ravy, S.; Silly, M.; Sirotti, F.

2012-01-01

Time resolved experiments are one of the major services that synchrotrons can provide to scientists. The short, high frequency and regular flashes of synchrotron light are a fantastic tool to study the evolution of phenomena over time. To carry out time resolved experiments, beamlines need to synchronize their devices with these flashes of light with a jitter shorter than the pulse duration. For that purpose, Synchrotron SOLEIL has developed the TimBeL (Timing Beamlines) board fully interfaced to TANGO framework. The TimBeL system is a compact PCI board. It is made of a mother with one daughter board. All functions are performed inside a FPGA (Field Programmable Gate Array) implemented on the mother board. A PLX Technology chip is used to communicate with the compact PCI crate. To enable experiments to remain always synchronous with the same bunch of electrons, the storage ring clock (CLK-SR) and the radio frequency clock (CLK-RF) are provided by the machine to beamlines. These clocks are used inside the FPGA as main clocks for state machines. Because the jitter is too large on the FPGA outputs, a daughter board with a jitter cleaner has been added to the system. This board also provides delay lines for compensating time offsets by 10 ps steps. This paper presents the main features required by time resolved experiments and how we achieved our goals with the TimBeL board

Plasma polarization spectroscopy. Time resolved spectroscopy in soft x-ray region on recombining plasma

International Nuclear Information System (INIS)

Iwamae, Atsushi; Hasuo, Masahiro; Atake, Makoto; Hasegawa, Noboru; Kawachi, Tetsuya

2007-01-01

We present an experimental study of polarization of emission radiations from recombining plasmas generated by the interaction of 60 fs ultra-short laser pulses with a gas jet. Time-resolved spectroscopy with a temporal resolution of 5 ps with repetitive accumulation is used to follow the recombination time histories. (author)

Theory of time-resolved inelastic x-ray diffraction

DEFF Research Database (Denmark)

Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm

2010-01-01

Starting from a general theory of time-resolved x-ray scattering, we derive a convenient expression for the diffraction signal based on a careful analysis of the relevant inelastic scattering processes. We demonstrate that the resulting inelastic limit applies to a wider variety of experimental...... conditions than similar, previously derived formulas, and it directly allows the application of selection rules when interpreting diffraction signals. Furthermore, we present a simple extension to systems simultaneously illuminated by x rays and a laser beam....

Removal of radium from aqueous solutions using adsorbent produced from coconut coir pith

International Nuclear Information System (INIS)

Zalina Laili; Muhamat Omar; Mohd Zaidi Ibrahim; Esther Phillip; Mohd Abdul Wahab Yusof; Hassan, A.

2008-08-01

A study was conducted to evaluate the potential use of the coconut coir pith as an adsorbent for the removal of radium from aqueous solutions. Experiments to establish adsorptions as a function of pH and contact time were carried out. The results showed that radium adsorption are dependent upon pH and contact time of coconut coir pith with aqueous solutions. 70-80% of radium were adsorbed in the neutral to alkaline pH range. The amount of radium adsorbed also increased with contact time, reaching an optimum after 250 min. Thus, it can be concluded that the coconut coir pith has the potential to be used as an adsorbent in radium removal from aqueous solutions. (Author)

Structure and function of proteins investigated by crystallographic and spectroscopic time-resolved methods

Science.gov (United States)

Purwar, Namrta

Biomolecules play an essential role in performing the necessary functions for life. The goal of this thesis is to contribute to an understanding of how biological systems work on the molecular level. We used two biological systems, beef liver catalase (BLC) and photoactive yellow protein (PYP). BLC is a metalloprotein that protects living cells from the harmful effects of reactive oxygen species by converting H2O2 into water and oxygen. By binding nitric oxide (NO) to the catalase, a complex was generated that mimics the Cat-H2O2 adduct, a crucial intermediate in the reaction promoted by the catalase. The Cat-NO complex is obtained by using a convenient NO generator (1-(N,N-diethylamino)diazen-1-ium-1,2-diolate). Concentrations up to 100˜200 mM are reached by using a specially designed glass cavity. With this glass apparatus and DEANO, sufficient NO occupation is achieved and structure determination of the catalase with NO bound to the heme iron becomes possible. Structural changes upon NO binding are minute. NO has a slightly bent geometry with respect to the heme normal, which results in a substantial overlap of the NO orbitals with the iron-porphyrin molecular orbitals. From the structure of the iron-NO complex, conclusions on the electronic properties of the heme iron can be drawn that ultimately lead to an insight into the catalytic properties of this enzyme. Enzyme kinetics is affected by additional parameters such as temperature and pH. Additionally, in crystallography, the absorbed X-ray dose may impair protein function. To address the effect of these parameters, we performed time-resolved crystallographic experiments on a model system, PYP. By collecting multiple time-series on PYP at increasing X-ray dose levels, we determined a kinetic dose limit up to which kinetically meaningful X-ray data sets can be collected. From this, we conclude that comprehensive time-series spanning up to 12 orders of magnitude in time can be collected from a single PYP

Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

International Nuclear Information System (INIS)

Ankjaergaard, C.

2010-02-01

Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

Energy Technology Data Exchange (ETDEWEB)

Ankjaergaard, C.

2010-02-15

Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

Time-resolved experiments in the frequency domain using synchrotron radiation (invited)

Science.gov (United States)

De Stasio, Gelsomina; Giusti, A. M.; Parasassi, T.; Ravagnan, G.; Sapora, O.

1992-01-01

PLASTIQUE is the only synchrotron radiation beam line in the world that performs time-resolved fluorescence experiments in frequency domain. These experiments are extremely valuable sources of information on the structure and the dynamics of molecules. This technique measures fluorescence lifetimes with picosecond resolution in the near UV spectral range. Such accurate measurements are rendered possible by taking phase and modulation data, and by the advantages of the cross-correlation technique. A successful experiment demonstrated the radiation damage induced by low doses of radiation on rabbit blood cell membranes.

The use of angle resolved electron and photon stimulated desorption for the determination of molecular structure at surfaces

International Nuclear Information System (INIS)

Madey, T.E.; Stockbauer, R.

1983-01-01

A brief review of recent data related to the use of angle-resolved electron stimulated desorption and photon stimulated desorption in determining the structures of molecules at surfaces is made. Examples include a variety of structural assignments based on ESIAD (electron stimulated desorption ion angular distributions), the observation of short-range local ordering effects induced in adsorbed molecules by surface impurities, and the application of photon stimulated desorption to both ionic and covalent adsorbate systems. (Author) [pt

Development of novel nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric.

Science.gov (United States)

Bondar, Yuliia; Kuzenko, Svetlana; Han, Do-Hung; Cho, Hyun-Kug

2014-01-01

A nanocomposite adsorbent based on potassium nickel hexacyanoferrate-loaded polypropylene fabric was synthesized for selective removal of Cs ions from contaminated waters by a two-stage synthesis: radiation-induced graft polymerization of acrylic acid monomer onto the nonwoven polypropylene fabric surface with subsequent in situ formation of potassium nickel hexacyanoferrate (KNiHCF) nanoparticles within the grafted chains. Data of scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the formation of KNiHCF homogeneous phase on the fabric surface, which consisted of crystalline cubic-shaped nanoparticles (70 to 100 nm). The efficiency of the synthesized adsorbent for removal of cesium ions was evaluated under various experimental conditions. It has demonstrated a rapid adsorption process, high adsorption capacity over a wide pH range, and selectivity in Cs ion removal from model solutions with high concentration of sodium ions.

The adsorber loop concept for the contact between seawater and adsorber granulate

International Nuclear Information System (INIS)

Koske, P.H.; Ohlrogge, K.

1984-01-01

For the production of 1 kg uranium from seawater about 10 9 kg seawater - depending on the extraction efficiency - have to be processed in a production plant. Such high seawater flows have to be put through adsorber beds the area of which depends on the flow velocity of the water in the bed. For a typical polyamidoxim (PAO) adsorber granulate with a grain size distribution of 0.3 to 1.2 mm the velocity in a fluidized bed is limited to about 1 cm/s in order to prevent carry out of the adsorber material. The consequences of this rather low bed velocity are large and expensive bed areas for technical production plants. The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the water before this is leaving the adsorption unit. This concept enables considerably higher seawater velocities thus reducing the bed area. Theoretical considerations are presented together with experimental results from field tests. (author)

Time-resolved UV-excited microarray reader for fluorescence energy transfer (FRET) measurements

Science.gov (United States)

Orellana, Adelina; Hokkanen, Ari P.; Pastinen, Tomi; Takkinen, Kristina; Soderlund, Hans

2001-05-01

Analytical systems based on immunochemistry are largely used in medical diagnostics and in biotechnology. There is a significant pressure to develop the present assay formats to become easier to use, faster, and less reagent consuming. Further developments towards high density array--like multianalyte measurement systems would be valuable. To this aim we have studied the applicability of fluorescence resonance energy transfer and time-resolved fluorescence resonance energy transfer in immunoassays on microspots and in microwells. We have used engineered recombinant antibodies detecting the pentameric protein CRP as a model analyte system, and tested different assay formats. We describe also the construction of a time-resolved scanning epifluorometer with which we could measure the FRET interaction between the slow fluorescence decay from europium chelates and its energy transfer to the rapidly decaying fluorophore Cy5.

Time-resolved luminescence from quartz: An overview of contemporary developments and applications

Energy Technology Data Exchange (ETDEWEB)

Chithambo, M.L., E-mail: m.chithambo@ru.ac.za [Department of Physics and Electronics, Rhodes University, PO BOX 94, Grahamstown 6140 (South Africa); Ankjærgaard, C. [Soil Geography and Landscape Group, Wageningen University Netherlands Centre for Luminescence Dating, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands (Netherlands); Pagonis, V. [McDaniel College, Physics Department, Westminster, MD 21157 (United States)

2016-01-15

Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al{sub 2}O{sub 3}:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.

Time-resolving electron temperature diagnostic for ALCATOR C

International Nuclear Information System (INIS)

Fairfax, S.A.

1984-05-01

A diagnostic that provides time-resolved central electron temperatures has been designed, built, and tested on the ALCATOR C Tokamak. The diagnostic uses an array of fixed-wavelength x-ray crystal monochromators to sample the x-ray continuum and determine the absolute electron temperature. The resolution and central energy of each channel were chosen to exclude any contributions from impurity line radiation. This document describes the need for such a diagnostic, the design methodology, and the results with typical ALCATOR C plasmas. Sawtooth (m = 1) temperature oscillations were observed after pellet fueling of the plasma. This is the first time that such oscillations have been observed with an x-ray temperature diagnostic

XPS and NEXAFS analysis of dimethyl sulfide adsorbed on the Rh(PVP) nanoparticle surface

International Nuclear Information System (INIS)

Niwa, Hironori; Ogawa, Satoshi; Yagi, Shinya; Kutluk, Galif

2010-01-01

We have studied the adsorption reaction of dimethyl sulfide (DMS: (CH 3 ) 2 S) on the surface of Rh(PVP) nanoparticles by using AFM, XPS and NEXAFS techniques. The AFM images show the degree of dispersion of the Rh(PVP) nanoparticles depends on the amount of them. The in-situ XPS results indicate that the dissociation reaction of DMS into atomic S does not depend upon the existence of the Rh(PVP) nanoparticles. The NEXAFS results show that there is a strong chemical bonding between Rh(PVP) nanoparticle and atomic S. The ex-situ XPS results show the atomic S adsorbed on the Rh(PVP) nanoparticles partially desorb by exposing to the air. (author)

Laser-time resolved fluorimetric determination of trace of boron in U3O8

International Nuclear Information System (INIS)

Xu Yongyuan; Wang Yulong; Wang Qin

1988-01-01

In this work, a laser-time resolved fluorimetric determinatin of trace of boron in U 3 O 8 had been developed. The boron complex with dibenzoyl methane (DBM) in a suitable medium is excited by a small nitrogen laser and emits the delay fluorescence with lifetime of 2 ms which is much longer than that of the fluorescence of uranium. Since the fluorescence of uranium doesn't interfere with determination of boron in the time resolved fluorimetric method boron need not be separated from uranium in advance. Thus the determination is very rapid and simple. The limit of determination is 0.02 ngB/ml. When 10 mgU is taken, 0.01 ppm of boron in uranium can be determined. Several samples of U 3 O 8 with boron content from 0.04 to 0.5 ppm have been determined by using this method. The results of determination have been accordant with other methods

Investigations into the Reusability of Amidoxime-Based Polymeric Adsorbents for Seawater Uranium Extraction

Energy Technology Data Exchange (ETDEWEB)

Kuo, Li-Jung [Marine; Pan, Horng-Bin [Department; Wai, Chien M. [Department; Byers, Margaret F. [Nuclear; Schneider, Erich [Nuclear; Strivens, Jonathan E. [Marine; Janke, Christopher J. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States; Das, Sadananda [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States; Mayes, Richard T. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States; Wood, Jordana R. [Marine; Schlafer, Nicholas [Marine; Gill, Gary A. [Marine

2017-09-29

The ability to re-use amidoxime-based polymeric adsorbents is a critical component in reducing the overall cost of the technology to extract uranium from seawater. This report describes an evaluation of adsorbent reusability in multiple re-use (adsorption/stripping) cycles in real seawater exposures with potassium bicarbonate (KHCO3) elution using several amidoxime-based polymeric adsorbents. The KHCO3 elution technique achieved ~100% recovery of uranium adsorption capacity in the first re-use. Subsequent re-uses showed significant drops in adsorption capacity. After the 4th re-use with the ORNL AI8 adsorbent, the 56-day adsorption capacity dropped to 28% of its original capacity. FTIR spectra revealed that there was a conversion of the amidoxime ligands to carboxylate groups during extended seawater exposure, becoming more significant with longer the exposure time. Ca and Mg adsorption capacities also increased with each re-use cycle supporting the hypothesis that long term exposure resulted in converting amidoxime to carboxylate, enhancing the adsorption of Ca and Mg. Shorter seawater exposure (adsorption/stripping) cycles (28 vs. 42 days) had higher adsorption capacities after re-use, but the shorter exposure cycle time did not produce an overall better performance in terms of cumulative exposure time. Recovery of uranium capacity in re-uses may also vary across different adsorbent formulations. Through multiple re-use the adsorbent AI8 can harvest 10 g uranium/kg adsorbent in ~140 days, using a 28-day adsorption/stripping cycle, a performance much better than would be achieved with a single use of the adsorbent through very long-term exposure (saturation capacity = 7.4 g U/kg adsorbent). A time dependent seawater exposure model to evaluate the cost associated with reusing amidoxime-based adsorbents in real seawater exposures was developed. The cost to extract uranium from seawater ranged from $610-830/kg U was predicted. Model simulation suggests that a short

Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals

DEFF Research Database (Denmark)

Grabow, Lars; Larsen, Britt Hvolbæk; Nørskov, Jens Kehlet

2010-01-01

Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced...... and the effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small...... influence on the position of the top of the volcano, that is, on which metal is the best catalyst....

Time-resolved ultraviolet laser-induced breakdown spectroscopy for organic material analysis

Energy Technology Data Exchange (ETDEWEB)

Baudelet, Matthieu; Boueri, Myriam [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1, UMR CNRS 5579, 43, Bd. du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Yu Jin [Laboratoire de Spectrometrie Ionique et Moleculaire, Universite Claude Bernard Lyon 1, UMR CNRS 5579, 43, Bd. du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)], E-mail: jin.yu@lasim.univ-lyon1.fr; Mao, Samuel S; Piscitelli, Vincent; Xianglei, Mao; Russo, Richard E [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2007-12-15

Ultraviolet pulses (266 nm) delivered by a quadrupled Nd:YAG laser were used to analyze organic samples with laser-induced breakdown spectroscopy (LIBS). We present characteristics of the spectra obtained from organic samples with special attentions on the emissions of organic elements, O and N, and molecular bonds CN. The choice of these atomic or molecular species is justified on one hand, by the importance of these species to specify organic or biological materials; and on the other hand by the possible interferences with ambient air when laser ablation takes place in the atmosphere. Time-resolved LIBS was used to determine the time-evolution of line intensity emitted from these species. We demonstrate different kinetic behaviors corresponding to different origins of emitters: native atomic or molecular species directly vaporized from the sample or those generated through dissociation or recombination due to interaction between laser-induced plasma and air molecules. Our results show the ability of time-resolved UV-LIBS for detection and identification of native atomic or molecular species from an organic sample.

TIME-RESOLVED INFRARED SPECTROSCOPY IN THE U121R BEAMLINE AT THE NSLS

International Nuclear Information System (INIS)

CARR, G.L.; LAVEIGNE, J.D.; LOBO, R.P.S.M.; REITZE, D.H.; TANNER, D.B.

1999-01-01

A facility for performing time-resolved infrared spectroscopy has been developed at the NSLS, primarily at beamline U12IR. The pulsed IR light from the synchrotron is used to perform pump-probe spectroscopy. The authors present here a description of the facility and results for the relaxation of photoexcitations in both a semiconductor and superconductor

Simple surface structure determination from Fourier transforms of angle-resolved photoemission extended fine structure

Energy Technology Data Exchange (ETDEWEB)

Zheng, Y. [Pennsylvania State Univ., University Park, PA (United States)]|[Lawrence Berkeley Lab., CA (United States); Shirley, D.A. [Pennsylvania State Univ., University Park, PA (United States)

1995-02-01

The authors show by Fourier analyses of experimental data, with no further treatment, that the positions of all the strong peaks in Fourier transforms of angle-resolved photoemission extended fine structure (ARPEFS) from adsorbed surfaces can be explicitly predicted from a trial structure with an accuracy of about {+-} 0.3 {angstrom} based on a single-scattering cluster model together with the concept of a strong backscattering cone, and without any additional analysis. This characteristic of ARPEFS Fourier transforms can be developed as a simple method for determining the structures of adsorbed surfaces to an accuracy of about {+-} 0.1 {angstrom}.

Characteristics of Microorganism's Fouling on Lithium Adsorbents in Okgye Harbor, Gangneung, Korea

Science.gov (United States)

Kim, J.; Yoon, H.; Kong, M.; Yoon, B.; Ryu, J.; Chung, K.; Kim, B.

2013-12-01

Marine microorganisms bring about serious ramification for nautical industry such as marine construction. Interaction of bacteria and phytoplankton causes biofouling to marine environments. To understand the marine microorganism's reaction on the inorganic surface, the experimental work carried out in pilot plant for lithium recovery field at Okgye Harbor, Gangneung, Korea through seasonal interval. To inquiry into the surface's effect for lithium recovery adsorbents by bacterial communities and phytoplankton, disk type inorganic adsorbents were immersed in same site at depth of 5 m for 7 days, 14 days and 21 days. Culturable marine bacteria were isolated and identified by 16S rRNA sequencing. Also, size and shape of marine organisms and the adsorption circumstance were investigated by SEM and CLSM (confocal laser scanning microscope). At longer exposure time of adsorbents, increase the bacterial number of individual. Vibrio sp., represented dominant species of biofouling after 21 days and marine phytoplankton increased 7 times after 7 days. Size of phytoplankton were about 50 ~ 100 μm in 0.25 mm2 area of lithium adsorbents. To increase lithium recovery rate of lithium adsorbents and to minimize the biofouling effects, it is necessary to conduct consistently field monitoring. Acknowledgments This research was supported by the national research project titled 'The Development of Technology for Extraction of Resources Dissolved in Seawater' of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Ocean and Fisheries.

Speciation of actinides in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

International Nuclear Information System (INIS)

Kimura, Takaumi; Kato, Yoshiharu; Meinrath, G.; Yoshida, Zenko; Choppin, G.R.

1995-01-01

Time-resolved laser-induced fluorescence spectroscopy (TRLFS) as a sensitive and selective method has been applied to the speciation of actinides in aqueous solution. Studies on hydrolysis and carbonate complexation of U(VI) and on determination of hydration number of Cm(III) are reported. (author)

Time resolved x-ray photography of a dense plasma focus

International Nuclear Information System (INIS)

Burnett, J.C.; Meyer, J.; Rankin, G.

1977-01-01

The temporal development of the hot plasma in a dense plasma focus is studied by x-ray streak photography of approximately 2 ns resolution time. It is shown that initially a uniform x-ray emitting pinch plasma is formed which subsequently cools down until x-ray emission stops after approximately 50 ns. At a time of around 100 ns after initial x-ray emission coinciding with the break-up time of the pinch a second burst of x-rays is observed coming from small localized regions. The observations are compared with results obtained from time-resolved shadow and schlieren photography of a similar dense focus discharge. (author)

Compact cryogenic Kerr microscope for time-resolved studies of electron spin transport in microstructures

NARCIS (Netherlands)

Rizo, P. J.; Pugzlys, A.; Liu, J.; Reuter, D.; Wieck, A. D.; van der Wal, C. H.; van Loosdrecht, P. H. M.; Pugžlys, A.

2008-01-01

A compact cryogenic Kerr microscope for operation in the small volume of high-field magnets is described. It is suited for measurements both in Voigt and Faraday configurations. Coupled with a pulsed laser source, the microscope is used to measure the time-resolved Kerr rotation response of

A high-order time-accurate interrogation method for time-resolved PIV

International Nuclear Information System (INIS)

Lynch, Kyle; Scarano, Fulvio

2013-01-01

A novel method is introduced for increasing the accuracy and extending the dynamic range of time-resolved particle image velocimetry (PIV). The approach extends the concept of particle tracking velocimetry by multiple frames to the pattern tracking by cross-correlation analysis as employed in PIV. The working principle is based on tracking the patterned fluid element, within a chosen interrogation window, along its individual trajectory throughout an image sequence. In contrast to image-pair interrogation methods, the fluid trajectory correlation concept deals with variable velocity along curved trajectories and non-zero tangential acceleration during the observed time interval. As a result, the velocity magnitude and its direction are allowed to evolve in a nonlinear fashion along the fluid element trajectory. The continuum deformation (namely spatial derivatives of the velocity vector) is accounted for by adopting local image deformation. The principle offers important reductions of the measurement error based on three main points: by enlarging the temporal measurement interval, the relative error becomes reduced; secondly, the random and peak-locking errors are reduced by the use of least-squares polynomial fits to individual trajectories; finally, the introduction of high-order (nonlinear) fitting functions provides the basis for reducing the truncation error. Lastly, the instantaneous velocity is evaluated as the temporal derivative of the polynomial representation of the fluid parcel position in time. The principal features of this algorithm are compared with a single-pair iterative image deformation method. Synthetic image sequences are considered with steady flow (translation, shear and rotation) illustrating the increase of measurement precision. An experimental data set obtained by time-resolved PIV measurements of a circular jet is used to verify the robustness of the method on image sequences affected by camera noise and three-dimensional motions. In

Time-resolved protein nano-crystallography using an X-ray free-electron laser

International Nuclear Information System (INIS)

Aquila, Andrew; Hunter, Mark S.; Fromme, Petra; Fromme, Raimund; Grotjohann, Ingo; Doak, R. Bruce; Kirian, Richard A.; Schmidt, Kevin E.; Wang, Xiaoyu; Weierstall, Uwe; Spence, John C.H.; White, Thomas A.; Caleman, Carl; DePonte, Daniel P.; Fleckenstein, Holger; Gumprecht, Lars; Liang, Mengning; Martin, Andrew V.; Schulz, Joachim; Stellato, Francesco; Stern, Stephan; Barty, Anton; Andreasson, Jakob; Davidsson, Jan; Hajdu, Janos; Maia, Filipe R.N.C.; Seibert, M. Marvin; Timneanu, Nicusor; Arnlund, David; Johansson, Linda; Malmerberg, Erik; Neutze, Richard; Bajt, Sasa; Barthelmess, Miriam; Graafsma, Heinz; Hirsemann, Helmut; Wunderer, Cornelia; Barends, Thomas R.M.; Foucar, Lutz; Krasniqi, Faton; Lomb, Lukas; Rolles, Daniel; Schlichting, Ilme; Schmidt, Carlo; Bogan, Michael J.; Hampton, Christina Y.; Sierra, Raymond; Starodub, Dmitri; Bostedt, Christoph; Bozek, John D.; Messerschmidt, Marc; Williams, Garth J.; Bottin, Herve

2012-01-01

We demonstrate the use of an X-ray free electron laser synchronized with an optical pump laser to obtain X-ray diffraction snapshots from the photo-activated states of large membrane protein complexes in the form of nano-crystals flowing in a liquid jet. Light-induced changes of Photosystem I-Ferredoxin co-crystals were observed at time delays of 5 to 10 μs after excitation. The result correlates with the microsecond kinetics of electron transfer from Photosystem I to ferredoxin. The undocking process that follows the electron transfer leads to large rearrangements in the crystals that will terminally lead to the disintegration of the crystals. We describe the experimental setup and obtain the first time resolved femtosecond serial X-ray crystallography results from an irreversible photo-chemical reaction at the Linac Coherent Light Source. This technique opens the door to time-resolved structural studies of reaction dynamics in biological systems. (authors)

Numerical study of friction of flake and adsorbed monolayer on atomically clean substrate

International Nuclear Information System (INIS)

Matsukawa, Hiroshi; Haraguchi, Kazuhiro; Ozaki, Shinsuke

2007-01-01

Frictional behaviors of flake and adsorbed monolayer on substrate can be observed by Frictional force microscope and Quartz crystal microbalance experiments and are typical problems in nano-friction. Computer simulations had been played important roles in understanding those behaviors, but in most of them the driving direction coincides with one of the crystal axes of the substrate. Here we report our numerical results of direction dependence of friction of flake and adsorbed monolayer. We found a new kind of dynamical phase transition in which flake and adsorbed monlayer change their structure relative to the substrate and make incommensurae structure to reduce kinetic frictional force after certain transition time. When the driving velocity is decreased the transition time tends to diverge at certain critical velocity for the flake. For the adsorbed monlayer the transition time tends to diverge at certain critical magnitudes of the external force or the interaction strength between adsorbates when they are decreased

Decay time shortening of fluorescence from donor-acceptor pair proteins using ultrafast time-resolved fluorescence resonance energy transfer spectroscopy

International Nuclear Information System (INIS)

Baba, Motoyoshi; Suzuki, Masayuki; Ganeev, Rashid A.; Kuroda, Hiroto; Ozaki, Tsuneyuki; Hamakubo, Takao; Masuda, Kazuyuki; Hayashi, Masahiro; Sakihama, Toshiko; Kodama, Tatsuhiko; Kozasa, Tohru

2007-01-01

We improved an ultrafast time-resolved fluorescence resonance energy transfer (FRET) spectroscopy system and measured directly the decrease in the fluorescence decay time of the FRET signal, without any entanglement of components in the picosecond time scale from the donor-acceptor protein pairs (such as cameleon protein for calcium ion indicator, and ligand-activated GRIN-Go proteins pair). The drastic decrease in lifetime of the donor protein fluorescence under the FRET condition (e.g. a 47.8% decrease for a GRIN-Go protein pair) proves the deformation dynamics between donor and acceptor fluorescent proteins in an activated state of a mixed donor-acceptor protein pair. This study is the first clear evidence of physical contact of the GRIN-Go proteins pair using time-resolved FRET system. G protein-coupled receptors (GPCRs) are the most important protein family for the recognition of many chemical substances at the cell surface. They are the targets of many drugs. Simultaneously, we were able to observe the time-resolved spectra of luminous proteins at the initial stage under the FRET condition, within 10 ns from excitation. This new FRET system allows us to trace the dynamics of the interaction between proteins at the ligand-induced activated state, molecular structure change and combination or dissociation. It will be a key technology for the development of protein chip technology

Time-resolved blood flow measurement in the in vivo mouse model by optical frequency domain imaging

Science.gov (United States)

Walther, Julia; Mueller, Gregor; Meissner, Sven; Cimalla, Peter; Homann, Hanno; Morawietz, Henning; Koch, Edmund

2009-07-01

In this study, we demonstrate that phase-resolved Doppler optical frequency domain imaging (OFDI) is very suitable to quantify the pulsatile blood flow within a vasodynamic measurement in the in vivo mouse model. For this, an OFDI-system with a read-out rate of 20 kHz and a center wavelength of 1320 nm has been used to image the time-resolved murine blood flow in 300 μμm vessels. Because OFDI is less sensitive to fringe washout due to axial sample motion, it is applied to analyze the blood flow velocities and the vascular dynamics in six-week-old C57BL/6 mice compared to one of the LDLR knockout strain kept under sedentary conditions or with access to voluntary wheel running. We have shown that the systolic as well as the diastolic phase of the pulsatile arterial blood flow can be well identified at each vasodynamic state. Furthermore, the changes of the flow velocities after vasoconstriction and -dilation were presented and interpreted in the entire physiological context. With this, the combined measurement of time-resolved blood flow and vessel diameter provides the basis to analyze the vascular function and its influence on the blood flow of small arteries of different mouse strains in response to different life styles.

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons.

Science.gov (United States)

Chiang, Hung-Lung; Lin, Kuo-Hsiung; Chen, Chih-Yu; Choa, Ching-Guan; Hwu, Ching-Shyung; Lai, Nina

2006-05-01

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.

Time-resolved X-ray transmission microscopy on magnetic microstructures

International Nuclear Information System (INIS)

Puzic, Aleksandar

2007-01-01

Three excitation schemes were designed for stroboscopic imaging of magnetization dynamics with time-resolved magnetic transmission X-ray microscopy (TR-MTXM). These techniques were implemented into two types of X-ray microscopes, namely the imaging transmission X-ray microscope (ITXM) and the scanning transmission X-ray microscope (STXM), both installed at the electron storage ring of the Advanced Light Source in Berkeley, USA. Circular diffraction gratings (Fresnel zone plates) used in both microscopes as focusing and imaging elements presently allow for lateral resolution down to 30 nm. Magnetic imaging is performed by using the X-ray magnetic circular dichroism (XMCD) as element specific contrast mechanism. The developed methods have been successfully applied to the experimental investigation of magnetization dynamics in ferromagnetic microstructures. A temporal resolution well below 100 ps was achieved. A conventional pump-probe technique was implemented first. The dynamic response of the magnetization excited by a broadband pulsed magnetic field was imaged spatially resolved using focused X-ray flashes. As a complementary method, the spatially resolved ferromagnetic resonance (SR-FMR) technique was developed for experimental study of magnetization dynamics in the frequency domain. As a third excitation mode, the burst excitation was implemented. The performance and efficiency of the developed methods have been demonstrated by imaging the local magnetization dynamics in laterally patterned ferromagnetic thin-film elements and three-layer stacks. The existence of multiple eigenmodes in the excitation spectra of ferromagnetic microstructures has been verified by using the pump-probe technique. Magnetostatic spin waves were selectively excited and detected with a time resolution of 50 ps using the SR-FMR technique. Thorough analysis of 20 in most cases independently prepared samples has verified that vortices which exhibit a low-amplitude switching of their core

Time-resolved luminescence of Eu2+-aggregate centers in CsBr crystals

International Nuclear Information System (INIS)

Zorenko, Yu.V.; Turchak, R.M.; Voznjak, T.I.; Stryganjuk, G.B.

2005-01-01

The luminescence of Eu 2+ -V Cs dipole centers and CsEuBr 3 aggregate centers, as well as the features of the energy transfer to these centers by excitons have been studied in CsBr:Eu crystals by means of investigation of the time-resolved emission spectra and luminescence decay kinetics under excitation by synchrotron radiation at RT. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Time-resolved terahertz spectroscopy of electrically conductive metal-organic frameworks doped with redox active species

Science.gov (United States)

Alberding, Brian G.; Heilweil, Edwin J.

2015-09-01

Metal-Organic Frameworks (MOFs) are three-dimensional coordination polymers that are well known for large pore surface area and their ability to adsorb molecules from both the gaseous and solution phases. In general, MOFs are electrically insulating, but promising opportunities for tuning the electronic structure exist because MOFs possess synthetic versatility; the metal and organic ligand subunits can be exchanged or dopant molecules can be introduced into the pore space. Two such MOFs with demonstrated electrical conductivity are Cu3(1,3,5-benzenetricarboxylate)2, a.k.a HKUST-1, and Cu[Ni(pyrazine-2,3-dithiolate)2]. Herein, these two MOFs have been infiltrated with the redox active species 7,7,8,8-tetracyanoquinodimethane (TCNQ) and iodine under solution phase conditions and shown to produce redox products within the MOF pore space. Vibrational bands assignable to TCNQ anion and triiodide anion have been observed in the Mid-IR and Terahertz ranges using FTIR Spectroscopy. The MOF samples have been further investigated by Time-Resolved Terehertz Spectroscopy (TRTS). Using this technique, the charge mobility, separation, and recombination dynamics have been followed on the picosecond time scale following photoexcitation with visible radiation. The preliminary results show that the MOF samples have small inherent photoconductivity with charge separation lifetimes on the order of a few picoseconds. In the case of HKUST-1, the MOF can also be supported by a TiO2 film and initial results show that charge injection into the TiO2 layer occurs with a comparable efficiency to the dye sensitizer N3, [cis-Bis(isothiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylato ruthenium(II)], and therefore this MOF has potential as a new light absorbing and charge conducting material in photovoltaic devices.

Theory of sum-frequency generation spectroscopy of adsorbed molecules using the density matrix method-broadband vibrational sum-frequency generation and applications

International Nuclear Information System (INIS)

Bonn, M; Ueba, H; Wolf, M

2005-01-01

A generalized theory of frequency- and time-resolved vibrational sum-frequency generation (SFG) spectroscopy of adsorbates at surfaces is presented using the density matrix formalism. Our theoretical treatment is specifically aimed at addressing issues that accompany the relatively novel SFG approach using broadband infrared pulses. The ultrashort duration of these pulses makes them ideally suited for time-resolved investigations, for which we present a complete theoretical treatment. A second key characteristic of these pulses is their large bandwidth and high intensity, which allow for highly non-linear effects, including vibrational ladder climbing of surface vibrations. We derive general expressions relating the density matrix to SFG spectra, and apply these expressions to specific experimental results by solving the coupled optical Bloch equations of the density matrix elements. Thus, we can theoretically reproduce recent experimentally demonstrated hot band SFG spectra using femtosecond broadband infrared excitation of carbon monoxide (CO) on a Ru(001) surface

Simultaneously time- and space-resolved spectroscopic characterization of laser-produced plasmas

International Nuclear Information System (INIS)

Charatis, G.; Young, B.K.F.; Busch, G.E.

1988-01-01

The CHROMA laser facility at KMS Fusion has been used to irradiate a variety of microdot targets. These include aluminum dots and mixed bromine dots doped with K-shell (magnesium) emitters. Simultaneously time- and space-resolved K-shell and L-shell spectra have been measured and compared to dynamic model predictions. The electron density profiles are measured using holographic interferometry. Temperatures, densities, and ionization distributions are determined using K-shell and L-shell spectral techniques. Time and spatial gradients are resolved simultaneously using three diagnostics: a framing crystal x-ray spectrometer, an x-ray streaked crystal spectrometer with a spatial imaging slit, and a 4-frame holographic interferometer. Significant differences have been found between the interferometric and the model-dependent spectral measurements of plasma density. Predictions by new non-stationary L-shell models currently being developed are also presented. 14 refs., 10 figs

Mass and Force Sensing of an Adsorbate on a Beam Resonator Sensor

Directory of Open Access Journals (Sweden)

Yin Zhang

2015-06-01

Full Text Available The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors, such as position and axial force, can also cause the shifts of resonant frequencies. The in situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as small as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated, and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of a mechanical resonator sensor for two reasons: reducing extra experimental equipment and achieving better mass sensing by considering more factors.

A system for time-resolved x-ray diffraction and its application to muscle contraction

International Nuclear Information System (INIS)

Amemiya, Yoshiyuki; Hashizume, Hiroo.

1979-01-01

A data-collection system has been built which permits time-resolved studies of X-ray diffraction diagrams obtained from contracting muscle on millisecond time scale. The system consists of a linear delay-line position sensitive proportional counter (PSPC), a special data transfer unit and an on-line computer. The PSPC used with a mirror-monochromator camera can detect equatorial reflections from stimulated muscle in a total exposure time of a few seconds. Time-resolved data-collection is achieved by stimulating muscle at a regular time interval, dividing a complete cycle of muscle contraction into many successive time slices and accumulating in computer memory X-ray data for each time slice from many repeated cycles of stimulation. The performances of the system have been demonstrated by recording equatorial reflections from frog skeletal muscle during isometric and isotonic twitch with a time resolution of 25 ms. (author)

In situ time-of-flight neutron imaging of NiO-YSZ anode support reduction under influence of stress

DEFF Research Database (Denmark)

Makowska, Malgorzata Grazyna; Strobl, Markus; Lauridsen, Erik M.

2016-01-01

This article reports on in situ macroscopic scale imaging of NiO-YSZ (YSZ is yttria-stabilized zirconia) reduction under applied stress - a phase transition taking place in solid oxide electrochemical cells in a reducing atmosphere of a hydrogen/nitrogen mixture and at operation temperatures of u...... of applying energy-resolved neutron imaging with both approaches to the NiO-YSZ reduction investigation indicate enhancement of the reduction rate due to applied stress, which is consistent with the results of the authors’ previous research....

High Pressure Scanning Tunneling Microscopy Studies of AdsorbateStructure and Mobility during Catalytic Reactions: Novel Design of anUltra High Pressure, High Temperature Scanning Tunneling MicroscopeSystem for Probing Catalytic Conversions

Energy Technology Data Exchange (ETDEWEB)

Tang, David Chi-Wai [Univ. of California, Berkeley, CA (United States)

2005-05-16

The aim of the work presented therein is to take advantage of scanning tunneling microscope’s (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 °C).

Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

Energy Technology Data Exchange (ETDEWEB)

Zhang Long [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Wang Tingmei [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu Peng [State Key Laboratory of Applied Organic Chemistry and Institute of Polymer Science and Engineering, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)], E-mail: pliu@lzu.edu.cn

2008-12-30

Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

Polyaniline-coated halloysite nanotubes via in-situ chemical polymerization

International Nuclear Information System (INIS)

Zhang Long; Wang Tingmei; Liu Peng

2008-01-01

Polyaniline coated halloysite nanotubes (PANI/HNTs) were prepared by the in-situ soapless emulsion polymerization of the anilinium chloride adsorbed halloysite nanotubes (HNTs), obtained by the dispersion of HNTs in acidic aqueous solution of aniline with magnetic stirring and ultrasonic irradiation, by using ammonium persulfate (APS) as oxidant. The effect of the acidities of the polymerizing media on the crystal structure of the nanotubes was investigated with X-ray diffraction (XRD) technique. The surface conducting coatings of the hybrids were characterized with X-ray photoelectron spectroscopy (XPS). The morphological analyses showed that the polyaniline coated halloysite nanotubes via the in-situ chemical oxidation polymerization with ultrasonic irradiation had the better well-defined structures, by the transmission electron microscopy (TEM). The conductivities of the PANI/HNTs hybrids increased with the increasing of the amounts of HCl dopant added in the emulsion polymerization.

Photon-Counting Arrays for Time-Resolved Imaging

Directory of Open Access Journals (Sweden)

I. Michel Antolovic

2016-06-01

Full Text Available The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach.

Multispectral fluorometric sensor for real time in-situ detection of marine petroleum spills

International Nuclear Information System (INIS)

Andrews, J.M.; Lieberman, S.H.

1998-01-01

This paper describes the development of a fluorescence based in-situ sensor system for real time monitoring and detection of petroleum hydrocarbon contaminants in the marine environment. The system consists of an array of underwater sensors deployed just below the water surface. The sensors can detect floating product (surface sheen) from below the surface as well as detect emulsified or dissolved phase petroleum in the water column. Data from each of the sensors is transmitted to a central base station computer for display, logging, and analysis. The primary intended use of the system is to protect marine facilities from accidental, petroleum discharges by providing responding authorities with immediate notification of the occurrence of a leak or spill. The detection of petroleum is based upon the fluorescence of polycyclic aromatic hydrocarbons found within petroleum derived products. The sensors utilize broadband ultraviolet excitation from a pulsed xenon lamp to generate fluorescence in contaminated sea water. The intensity of the resulting fluorescence emission is proportional to both the oil concentration in water, and/or the oil film thickness on the water surface. Multispectral fluorescence emission information is used to distinguish between several possible petroleum classes and eliminate false positive interference from non-petroleum based fluorophores such as chlorophyll. Real time qualitative identification yields an important advantage in terms of rapidly resolving questions of spill origin or in determining an appropriate response. To enable long term underwater deployment, the optical energy of the ultraviolet excitation source also serves to prevent the occurrence of biofouling on the surface of the optical window. The results of initial testing in San Diego Harbor and at the Ohmsett wave tank facility in New Jersey demonstrate the system's ability to detect petroleum products under a variety of conditions, including the presence of strong harbor

Photoemission studies of clean and adsorbate covered metal surfaces using synchrotron and uv radiation sources