Sample records for cryochemistry
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Shabatina, Tatyana I.; Sergeev, Gleb B.
2010-01-01
This survey of literature data and of the results obtained by the authors of the review shows that the methods of cryochemistry and cryonanochemistry make it possible to carry out and control self-assembling processes of metal atoms to form subnano- and nanosized aggregates, perform competitive chemical interactions of atoms, small clusters and nanosized metal particles with different organic and inorganic substances. At present time the effective approaches of cryochemistry are being develop...
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Cryochemistry of Metal Nanoparticles
International Nuclear Information System (INIS)
Sergeev, Gleb B.
2003-01-01
The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia
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Cryochemistry of Metal Nanoparticles
Energy Technology Data Exchange (ETDEWEB)
Sergeev, Gleb B. [Moscow State University, Laboratory of Low Temperature Chemistry, Chemistry Department (Russian Federation)], E-mail: gbs@kinet.chem.msu.ru
2003-12-15
The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia.
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Cryochemistry of Metal Nanoparticles
Sergeev, Gleb B.
2003-12-01
The interaction of metal atoms, clusters and nanoparticles with different organic and inorganic substances were studied at low temperature (10-40K). Combination of matrix isolation technique and preparative cryochemistry was applied for the investigation of activity and selectivity of metal particles of different size. Encapsulation of metal nanoparticles in polymers was studied. The metal-polymer films thus obtained exhibited satisfactory sensitivity to ammonia.
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Cryochemistry (2nd revised edition)
Energy Technology Data Exchange (ETDEWEB)
Sergeev, G.B.; Batiuk, V.A.
1986-01-01
Chemical reactions at low temperatures are characterized, summarizing the results of Soviet research since the late 1950s. Chapters are devoted to homogeneous and heterogeneous low-temperature reactions of gases and liquids, apparatus and techniques for cryochemistry, reactions of ions and radicals in frozen solids, low-temperature polymerization, chain reactions, spontaneous reactions, kinetic models of solid-phase reactions, reactions in multicomponent frozen systems, biochemical reactions at reduced and low temperatures, reactions involving metals, and science and engineering applications of low temperatures. 813 references.
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International Nuclear Information System (INIS)
Mayer, J.; Plonka, A.; Ratajski, A.; Suwalski, J.P.; Wypych, M.
1978-01-01
The adaptation of the commercially available closed cycle refrigeration system Spectrim sup(TM) for radiation cryochemistry experiments with frozen matrices down to 14 K is described. The cold head of Spectrim sup(TM), equipped with vacuum shroud extensions and sample holders proper for the given type of experiments, was contained in lead shields, provided with special entrances for irradiation of samples with 60 Co γ-rays. The shroud extensions used for ESR and optical absorption measurements and the sample holders for isothermal luminescence and radiothermolumininescence measurements are described. (U.K.)
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Introduction to Free Atoms and Particles.
1986-01-01
34 Vol. I (R. Abramovitch. ed.). pp. 42. 46. 47. 44. 65, Plenum, New York. 1979. 9. P. L. Timms. in " Cryochemistry " (M. Moskovits and G. Ozin. eds.). p. 61...in ’ Cryochemistry " (M. Moskovits and G. Ozin. eds.). p. 261. * Wiley (interscicnce). New York, 1976. 15. R. H. Hauge, S. E. Grandsen. and J. L
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1994-01-01
A two-part symposium was held concerning topics in Solar System chemistry. The first part covered the organic chemistry ofsmall bodies of the interplanetray medium. It produced papers on the evolution, spectral properties and composition of organic matter in comets, interplanetary dust and asteroids. The second part covered cryochemistry and exobiology in planetary atmospheres (gas giant planets and their satellites) and in various astronomical ices.
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Klabunde, Kenneth J
2013-01-01
The second edition of Nanochemistry covers the main studies of nanoparticle production, reactions, and compounds, and reviews the work of leading scientists from around the world. This book is the first monograph on nanochemistry, giving perspectives on the present status and future possibilities in this rapidly advancing discipline. It provides the solid fundamentals and theory of nanoscience, and progress through topics including synthesis and stabilization of nanoparticles, cryochemistry of metal atoms and nanoparticles, chemical nanoreactors, and more. Nanoparticles are capable of transfor
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[Morphological changes in tongue cancer after cryosurgery].
Zhou, X D; Mao, T Q
1993-01-01
Tca 8113 (human tongue cancer cell line) cell transplanted tumors in nude mice were treated with cryosurgery for three freeze-thaw cycles. Tumor samples were obtained by biopsies pre- and post-cryosurgery for morphological study. The results showed intercellular adhesion damage, nuclear pyknosis, cell death, etc. One week after, the deep parts of the frozen samples were similar to that of the untreated ones. Our study indicates the change of biomembrance may be also important as of nuclei in cell death and may play an important role in the treatment of cancer by cryochemistry.
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New model system in radiation cryochemistry. Hyperquenched glassy water
International Nuclear Information System (INIS)
Plonka, A.
1998-01-01
Complete text of publication follows. Since the radical generated by high-energy irradiation of liquid water are short-lived at ambient temperature, they are often studied at cryogenic temperatures after irradiating either crystalline ice or highly concentrated aqueous electrolyte solution glasses. While these studies provided a wealth of information, they also bear disadvantages in that further reactions of these radicals may not be those occurring in liquid water because of formation of other radicals from the solute in the case of the electrolyte solution glass and/or perturbation of the water structure by the solute. Furthermore, in slow-cooled aqueous solutions where ice is formed and phase separation of the solute occurs, the radicals trapped in the ice compartments are unable to interact with solutes because these are dissolved in the 'freeze-concentration' regions. These problems can in principle be overcome by investigating water and dilute aqueous solutions in their glassy states which can be obtained by rapid quenching of the liquids. Glassy water can now routinely be made in gram-quantities by so-called 'hyperquenching' of micrometer-sized water droplets on a solid cryoplate. The cooling rates are of the order of 10 6 - 10 7 K s -1 . Our results show that indeed in the hyperquenched dilute aqueous solutions there is no problem with phase separation and radiolysis of hyperquenched water is quite distinct from radiolysis of polycrystalline ice obtained from liquid water quenched in the liquid nitrogen
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New model system in radiation cryochemistry:. hyperquenched glassy water
Bednarek, Janusz; Plonka, Andrzej; Hallbrucker, Andreas; Mayer, Erwin
1999-08-01
Radicals generated by high-energy irradiation of liquid water, short-lived at ambient temperature, can be studied at cryogenic temperatures after irradiating water and dilute aqueous solutions in their glassy states which can be obtained by so-called hyperquenching of the liquids at cooling rates of ˜10 6-10 7 K s -1. In the glassy states of hyperquenched dilute aqueous solutions there is no problem with phase separation and radiolysis of glassy water is quite distinct from radiolysis of polycrystalline ice obtained from liquid water on slow-cooling in liquid nitrogen.
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Cryochemistry: freezing effect on peptide coupling in different organic solutions.
Vajda, T; Szókán, G; Hollósi, M
1998-06-01
The freezing effect on peptide coupling in organic solutions of different polarity has been investigated and compared with the results obtained in liquid phase. The model reaction of DCC-activated coupling of Boc-Ala-Phe-OH with H-Ala-OBu(t) has been carried out in dioxane, dimethylsulfoxide and formamide, as well as in mixtures (90%/10%, v/v) of dioxane with acetonitrile, dimethylformamide, dimethylsulfoxide and formamide. The reactions have been traced and evaluated by RP-HPLC analysis. Freezing the reaction mixture resulted in all cases in a significant suppression of the N-dipeptidylurea side-product formation together with a slight decrease of tripeptide epimerization. The coupling yields and the side effects depended on the solvent, with the dioxane and dioxane/acetonitrile mixture produced the best results. The role of freezing and solvent in the improved results is discussed.
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Applications of Satellite Observations of Tropospheric Composition
Monks, Paul S.; Beirle, Steffen
A striking feature of the field of tropospheric composition is the sheer number of chemical species that have been detected and measured with satellite instruments. The measurements have found application both in atmospheric chemistry itself, providing evidence, for example, of unexpected cryochemistry in the Arctic regions, and also in environmental monitoring with, for example, the observed growth in NO2 emissions over eastern Asia. Chapter 8 gives an overview of the utility of satellite observations for measuring tropospheric composition, dealing with each of the many compounds seen in detail. A comprehensive compound by compound table of the many studies performed is a most useful feature.
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Chemiluminescence in cryogenic matrices
Lotnik, S. V.; Kazakov, Valeri P.
1989-04-01
The literature data on chemiluminescence (CL) in cryogenic matrices have been classified and correlated for the first time. The role of studies on phosphorescence and CL at low temperatures in the development of cryochemistry is shown. The features of low-temperature CL in matrices of nitrogen and inert gases (fine structure of spectra, matrix effects) and the data on the mobility and reactivity of atoms and radicals at very low temperatures are examined. The trends in the development of studies on CL in cryogenic matrices, such as the search for systems involving polyatomic molecules and extending the forms of CL reactions, are followed. The reactions of active nitrogen with hydrocarbons that are accompanied by light emission and CL in the oxidation of carbenes at T >= 77 K are examined. The bibliography includes 112 references.
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Chemical reactivity of hydrogen, nitrogen, and oxygen atoms at temperatures below 100 k
Mcgee, H. A., Jr.
1973-01-01
The synthesis of unusual compounds by techniques employing cryogenic cooling to retard their very extreme reactivity was investigated. Examples of such species that were studied are diimide (N2H2), cyclobutadiene (C4H4), cyclopropanone (C3H4O), oxirene (C2H2O), and many others. Special purpose cryogenically cooled inlet arrangements were designed such that the analyses incurred no warm-up of the cold, and frequently explosively unstable, compounds. Controlled energy electron impact techniques were used to measure critical potentials and to develop the molecular energetics and thermodynamics of these molecules and to gain some insight into their kinetic characteristics as well. Three and four carbon strained ring molecules were studied. Several reactions of oxygen and hydrogen atoms with simple molecules of H, N, C, and O in hard quench configurations were studied. And the quench stabilization of BH3 was explored as a model system in cryochemistry.
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Low temperature surface chemistry and nanostructures
Sergeev, G. B.; Shabatina, T. I.
2002-03-01
The new scientific field of low temperature surface chemistry, which combines the low temperature chemistry (cryochemistry) and surface chemistry approaches, is reviewed in this paper. One of the most exciting achievements in this field of science is the development of methods to create highly ordered hybrid nanosized structures on different organic and inorganic surfaces and to encapsulate nanosized metal particles in organic and polymer matrices. We consider physical and chemical behaviour for the systems obtained by co-condensation of the components vapours on the surfaces cooled down to 4-10 and 70-100 K. In particular the size effect of both types, the number of atoms in the reactive species structure and the thickness of growing co-condensate film, on the chemical activity of the system is analysed in detail. The effect of the internal mechanical stresses on the growing interfacial co-condensate film formation and on the generation of fast (explosive) spontaneous reactions at low temperatures is discussed. The examples of unusual chemical interactions of metal atoms, clusters and nanosized particles, obtained in co-condensate films on the cooled surfaces under different conditions, are presented. The examples of highly ordered surface and volume hybrid nanostructures formation are analysed.
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International Nuclear Information System (INIS)
Pasternak, M.
1978-05-01
Moessbauer studies on 129 I, 57 Fe and 119 Sn were conducted in several disordered and microscopic systems in order to investigate properties of lattice dynamics, chemical bonding and phase transitions. The project included the following studies: (1) Granular crystals of Sn embedded in tin-oxide matrix; the nature of the superconductivity transition of very small grains of tin was investigated. (2) Lattice dynamics and characterization of amorphous tin oxide obtained by condensing atoms of Sn and O 2 gas on a 77 K substrate. The hyperfine interaction and the temperature dependence of the Debye-Waller factor were essential to determine the structure of the amorphous tin oxide. (3) The nature of the chemical bond of the alkaly halides ionic crystals and molecules; molecules of Li, Na, K, Rb and Cs iodides were trapped in agron matrices, and the isomer-shift values were obtained from absorption spectra. (4) Binding of single iron and tin atoms to CH 4 , NH 3 , H 2 and C 6 H 6 molecules, with samples at low temperatures between 2 and 77 K; conclusions were derived regarding the cryochemistry of these systems, as related to fundamental problems of catalysis, chemisorption and ''cracking'' of organic molecules
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Thermal theory of autowave processes in low-temperature solid-phase radiochemical reactions
International Nuclear Information System (INIS)
Barelko, V.V.; Barkalov, I.M.; Vaganov, D.A.; Zanin, A.M.; Kiryukhin, D.P.
1982-01-01
A new phenomenon in radiation cryochemistry concerning the class of autowave processes was previously discovered. It was observed in halogenation and hydrohalogenation of hydrocarbons and consisted of spontaneous, laminar propagation of a chemical transformation wave based on a frozen mixture of reagents previously irradiated with 60 Co γ-rays. The effect of the positive inverse correlation between the chemical conversion and brittle fracture of a solid sample of reagents is the phenomenological basis of the phenomenon; formation of fractures triggers a reactive process which takes place on their active surface (or in the layer adjacent to it), and the chemical reaction, in turn, stimulates the subsequent development of the process of decomposition. As a result, a single brittle fracture and chemical conversion wave which moves along the solid sample arises. Different mechanisms of generation of fracture surfaces under the effect of the reaction are possible. A difference in the densities of the initial reagents and the products of the reaction could be one of the causes of brittle fracture, and the thermal stresses induced by the exothermicity of the chemical processes could be another cause. The present work concerns the analysis of the features of the wave process which occurs based on the second, thermal mechanism. The analysis was conducted within the framework of a phenomenological approach which does not require specific definition of the nature of the chemical activation of the system during its brittle fracture
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Aggregation-induced chemical reactions: acid dissociation in growing water clusters.
Forbert, Harald; Masia, Marco; Kaczmarek-Kedziera, Anna; Nair, Nisanth N; Marx, Dominik
2011-03-23
Understanding chemical reactivity at ultracold conditions, thus enabling molecular syntheses via interstellar and atmospheric processes, is a key issue in cryochemistry. In particular, acid dissociation and proton transfer reactions are ubiquitous in aqueous microsolvation environments. Here, the full dissociation of a HCl molecule upon stepwise solvation by a small number of water molecules at low temperatures, as relevant to helium nanodroplet isolation (HENDI) spectroscopy, is analyzed in mechanistic detail. It is found that upon successive aggregation of HCl with H(2)O molecules, a series of cyclic heteromolecular structures, up to and including HCl(H(2)O)(3), are initially obtained before a precursor state for dissociation, HCl(H(2)O)(3)···H(2)O, is observed upon addition of a fourth water molecule. The latter partially aggregated structure can be viewed as an "activated species", which readily leads to dissociation of HCl and to the formation of a solvent-shared ion pair, H(3)O(+)(H(2)O)(3)Cl(-). Overall, the process is mostly downhill in potential energy, and, in addition, small remaining barriers are overcome by using kinetic energy released as a result of forming hydrogen bonds due to aggregation. The associated barrier is not ruled by thermal equilibrium but is generated by athermal non-equilibrium dynamics. These "aggregation-induced chemical reactions" are expected to be of broad relevance to chemistry at ultralow temperature much beyond HENDI spectroscopy.
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Kinetic calorimetry in the study of the mechanism of low-temperature chemical reactions
Barkalov, I. M.; Kiryukhin, D. P.
schemes are described [1-5]. However, despite the high working characteristics of modern calorimeters (Perkin-Elmer, Du Pont, LKB, etc.), all of them have one principal disadvantage: a cell with a sample is placed in them at room temperature. In cryochemical investigation, when the sample has metastable formations, the loading is made `from nitrogen to nitrogen', i.e. the sample prepared at 77 K should be loaded into a calorimeter at 77 K. Besides, the existing installations do not allow measurements at the temperatures Cryochemistry and Radiation Chemistry at the Institute of Chemical Physics in Chernogolovka has created original calorimetric techniques which allow: (1) the carrying out phase analysis and the determination of the main thermodynamic characteristic of individual substances and complicated systems in the temperature range 5 300 K. Sample loading can be conducted at 77 K that allows us to study the systems containing: tetrafiuoroethylene, hexafluoropropylene, ethylene, carbon monoxide, nitrogen, methane, hydrogen, oxygen, ozone, formaldehyde and many other gaseous substances; (2) the study of the dynamics of chemical reactions and to measure the main kinetic parameters of the processes-the elementary rate constants and the activation energies. The experiment can be conducted both under direct action of radiation and UV light and in the post-effect mode [5,6].
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PERSPECTIVE: Snow matters in the polar regions
Sodeau, John
2010-03-01
relatively long history of this topic was surveyed extensively in 2007 and the answer is probably not related to the photolysis of the halogeno-carbons although the transformation processes are still not completely understood (Simpson et al 2007). This topic along with the potential involvement of both iodine and chlorine species is decidedly 'hot' in the intriguing world of polar cryochemistry. The Antony et al (2010) paper is actually entitled 'Is cloud seeding in coastal Antarctica linked to bromine and nitrate variability in snow?'. Although the nitrate ions were discussed in terms of being a simple nutrient in the study, the photochemistry of nitrate ions in snow has actually become an important focus of research in the laboratory. A further review by Grannas et al (2007) is recommended in this respect. But important questions remain regarding the fate of the NO and NO2 molecules produced in the primary photolytic channels, especially if concentrated into ice 'micropockets' (Hellebust et al 2007). Furthermore the impacts of newly discovered reactions such as HO2/NO to directly produce nitric acid, at the expense of NOx, have not yet been quantified in the polar ABL context (Cariolle et al 2008). Then there is peroxyacetylnitrate (PAN; Mills et al 2007) and other organo-nitrates and their possible interactions with mercury and the halides . . . Clearly, Antarctica is not chemically pristine and snow-ice interfaces in both the laboratory and the field have become a very challenging medium for exploring new and unexpected chemistry relevant to our atmosphere. References Abbatt J P D 1994 Heterogeneous reaction of HOBr with HBr and HCl on ice surfaces at 228 K Geophys. Res. Lett. 21 665-8 Antony R et al 2010 Is cloud seeding in coastal Antarctica linked to bromine and nitrate variability in snow? Environ. Res. Lett. 5 014009 Cariolle D et al 2008 Impact of the new HNO3-forming channel of the HO2 + NO reaction on tropospheric HNO3, NOx, HOx and ozone Atmos. Chem. Phys. 8