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1.
A.V. Eremin E.V. Gurentsov M. Hofmann B.F. Kock C. Schulz 《Applied physics. B, Lasers and optics》2006,83(3):449-454
Time-resolved laser-induced incandescence (TR-LII) was applied for the determination of particle sizes during carbon-particle formation from supersaturated atomic carbon vapor that was generated by laser photolysis of carbon suboxide (C3O2) at room temperature. Thus, the solid carbon particles were formed under hydrogen-free conditions. The TR-LII technique was used for in situ size measurement of growing carbon particles and samples of final particles were analyzed by transmission electron microscopy (TEM). It was found that the particles grow to a final size of 4–12 nm within 0.02–1 ms. The properties of the obtained particles depend on the initial conditions in the reaction volume, i.e. concentration of carbon suboxide, pressure and type of gas diluter, photolysis wavelength, and laser pulse energy. The comparison of TR-LII and TEM particle sizing results yields information about the effective thermal energy accommodation coefficients for He, Ar, CO, and C3O2 molecules on carbon particles. PACS 61.46.Df; 07.60.-j; 78.70.-g 相似文献
2.
An attempt was made to obtain iron-carbon nanoparticles by two-step pyrolysis of Fe(CO)5- and C3O2-containing mixtures behind incident and reflected shock waves in a shock tube. The formation of binary particles was monitored by recording the extinction of He-Ne laser radiation and laser-induced incandescence (LII). The LII method provides particle size estimates if the thermal and optical properties of the constituting material are known. Behind an incident shock wave, at temperatures of 700–1500 K, Fe(CO)5 decomposes within a short period of time (∼50 µs). The resulting iron atoms combine into particles, which serve as condensation nuclei for carbon vapor resulting from C3O2 pyrolysis at 1500–3000 K behind the reflected shock wave. The binary particles thus produced are considerably larger than pure carbon or iron particles. As the mixture temperature behind the reflected shock wave is raised, the diameter of these binary particles decreases.__________Translated from Kinetika i Kataliz, Vol. 46, No. 3, 2005, pp. 333–343.Original Russian Text Copyright © 2005 by Gurentsov, Eremin, Roth, Starke.Based on a report at the VI Russian Conference on Mechanisms of Catalytic Reactions (Moscow, October 1–5, 2002). 相似文献
3.
E. V. Gurentsov 《Kinetics and Catalysis》2017,58(3):233-254
This review deals with the UV laser photodissociation of metal carbonyls, ferrocene, carbon suboxide, and other precursors. The formation of supersaturated atomic vapors followed by the formation of carbon, metal, and metal–carbon nanoparticles is discussed. Application of UV laser synthesis to preparation of catalytic nanomaterials is considered. 相似文献
4.
Technical Physics - Evaporation of iron nanoparticles in carbon shells under pulsed laser irradiation is analyzed. Iron–carbon nanoparticles are synthesized in a shock tube reactor with the... 相似文献
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I.?R.?Barabanov L.?B.?Bezrukov A.?V.?Veresnikova Yu.?M.?Gavrilyuk A.?M.?Gangapshev V.?Yu.?Grishina V.?I.?Gurentsov V.?P.?Zavarzina V.?V.?Kazalov S.?D.?Krokhaleva V.?V.?Kuz’minov A.?S.?Kurlovich B.?K.?Lubsandorzhiev S.?B.?Lubsandorzhiev A.?K.?Mezhokh V.?P.?Morgalyuk P.?Yu.?Naumov G.?Ya.?Novikova V.?B.?Petkov A.?M.?Pshukov A.?Yu.?Sidorenkov V.?V.?SinevEmail author Sh.?I.?Umerov E.?A.?Yanovich T.?Enquist P.?Kuusiniemi J.?Joutsenvaara A.?Virkajarvi 《Physics of Atomic Nuclei》2017,80(6):1146-1152
A setup for measuring natural-radioactivity backgrounds and ultralow concentrations of the isotope 14C in samples of a liquid organic scintillator was created at the low-background laboratory of the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) at a depth of 4900 mwe. The concentration of the radiocarbon 14C in a sample of a scintillator based on domestically produced linear alkylbenzene was measured, and it was found that 14C/12C (3.3 ± 0.5) × 10?17. 相似文献
6.
E. V. Gurentsov A. V. Eremin R. N. Kolotushkin D. N. Khmelenin Yu. V. Grigoriev 《Kinetics and Catalysis》2020,61(2):224-231
The decomposition of methane on molybdenum nanoparticles was studied experimentally at room temperature. The molybdenum nanoparticles were synthesized in the gas phase using UV laser photolysis of Mo(CO)6 vapor in a flow reactor. The working part of the flow reactor was equipped with quartz windows for introducing the radiation from a pulsed Nd:YaG laser operating at the fourth harmonic (266 nm) at a frequency of 10 Hz. Methane was used as a carrier gas. As a result of irradiation of a mixture of methane with Mo(CO)6 vapors in the gas phase at room temperature, nanoparticles with sizes of 2–50 nm were synthesized. The phase composition of the nanoparticles included pure molybdenum, molybdenum carbide Mo2C, and molybdenum oxide MoO3. During the reaction, the hydrogen yield was measured with a VG-7 highly sensitive hydrogen analyzer based on a semiconductor metal–dielectric sensor. The measured H2 concentration varied from 5 to 25 ppm depending on the concentration of Mo(CO)6. The possibility of methane decomposition on molybdenum nanoparticles at room temperature was discussed based on the obtained data. 相似文献
7.
A. Eremin E. Gurentsov E. Popova K. Priemchenko 《Applied physics. B, Lasers and optics》2011,104(2):285-295
The evidence of the change of the complex refractive index function E(m) of carbon and iron nanoparticles as a function of their size was found from two-color time-resolved laser-induced incandescence
(TiRe-LII) measurements. Growing carbon particles were observed from acetylene pyrolysis behind a shock wave and iron particles
were synthesized by pulse Kr–F excimer laser photo-dissociation of Fe(CO)5. The magnitudes of refractive index function were found through the fitting of two independently measured values of particle
heat up temperature, determined by two-color pyrometry and from the known energy of the laser pulse and the E(m) variation. Small carbon particles of about 1–14 nm in diameter had a low value of E(m)∼0.05–0.07, which tends to increase up to a value of 0.2–0.25 during particle growth up to 20 nm. Similar behavior for iron
particles resulted in E(m) rise from ∼0.1 for particles 1–3 nm in diameter up to ∼0.2 for particles >12 nm in diameter. 相似文献
8.
Barabanov I. R. Bezrukov L. B. Gurentsov V. I. Novikova G. Ya. Sinev V. V. Yanovich E. A. 《Physics of Atomic Nuclei》2022,85(4):402-410
Physics of Atomic Nuclei - A modification of the LENS (Low Energy Neutrino Spectroscopy) project for spectroscopy of solar neutrinos with energies above about 715 keV on the basis of new... 相似文献
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10.
I. R. Barabanov L. B. Bezrukov V. I. Gurentsov B. L. Zhuykov S. V. Kianovsky V. N. Kornoukhov V. M. Kohanuk E. A. Yanovich 《Physics of Atomic Nuclei》2010,73(7):1106-1110
The cross sections for the production of the radioactive isotopes 74As, 68Ge, 65Zn, and 60Co in metallic germanium irradiated with 100-MeV protons were measured, the experiments being performed both with germanium
of natural isotopic composition and germanium enriched in the isotope 76Ge. The targets were irradiated with a proton beam at the facility for the production of radionuclides at the accelerator
of the Institute for Nuclear Research (INR, Moscow). The data obtained will further be used to calculate the background of
radioactive isotopes formed by nuclear cascades of cosmic-ray muons in new-generation experiments devoted to searches for
the neutrinoless double-beta decay of 76Ge at underground laboratories. 相似文献