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Author Gershenzon, E. M.; Gershenson, M. E.; Goltsman, G. N.; Lyulkin, A. M.; Semenov, A. D.; Sergeev, A. V.
Title Limiting characteristics of fast-response superconducting bolometers Type Journal Article
Year 1989 Publication Zhurnal Tekhnicheskoi Fiziki Abbreviated Journal Zhurnal Tekhnicheskoi Fiziki
Volume (down) 59 Issue 2 Pages 11-120
Keywords HEB
Abstract Теоретически и экспериментально исследовано физическое ограничение быстродействия сверхпроводящего болометра. Показано, что минимальная постоянная времени реализуется в условиях электронного разогрева и определяется процессом неупругого электрон-фонон-ного взаимодействия. Сформулированы требования к конструкции «электронного болометра» для достижения предельной чувствительности. Проведено сравнение характеристик электрон­ного болометра и обычных болометров различных типов.
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Notes Approved no
Call Number Serial 1696
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Author Lang, P. T.; Leipold, I.; Knott, W. J.; Semenov, A. D.; Gol'tsman, G. N.; Renk, K. F.
Title New far-infrared laser lines from CH3Cl and CH3Br optically pumped with a continuously tunable high pressure CO2 laser Type Journal Article
Year 1991 Publication Appl. Phys. B Abbreviated Journal Appl. Phys. B
Volume (down) 53 Issue 4 Pages 207-212
Keywords CO2 IR lasers, applications, CH3Cl, CH3Br
Abstract In this paper we report on the detection of new far-infrared laser lines from CH3Cl and CH3Br optically pumped with a continuously tunable high pressure CO2 laser. We found 80 new lines for CH3Cl and 9 new lines for CH3Br in the frequency region between 16 cm−1 and 41 cm−1, all due to stimulated Raman scattering. For the Raman gain regions bandwidths up to about 700 MHz were found. We also observed high intensity short far-infrared laser pulses of durations in the nanosecond regime.
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Series Volume Series Issue Edition
ISSN 0721-7269 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number Serial 1678
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Author Semenov, A. D.; Nebosis, R. S.; Gousev, Yu. P.; Heusinger, M. A.; Renk, K. F.
Title Analysis of the nonequilibrium photoresponse of superconducting films to pulsed radiation by use of a two-temperature model Type Journal Article
Year 1995 Publication Phys. Rev. B Abbreviated Journal Phys. Rev. B
Volume (down) 52 Issue 1 Pages 581-590
Keywords HEB, NbN phonon scecific heat, Cp
Abstract Photoresponse of a superconducting film in the resistive state to pulsed radiation has been studied in the framework of a model assuming that two different effective temperatures can be assigned to the quasiparticle and phonon nonequilibrium distributions. The coupled electron-phonon-substrate system is described by a system of time-dependent energy-balance differential equations for effective temperatures. An analytical solution of the system is given and calculated voltage transients are compared with experimental photoresponse signals taking into account the radiation pulse shape and the time resolution of the readout electronics. It is supposed that a resistive state (vortices, fluxons, network of intergrain junctions, hot spots, phase slip centers) provides an ultrafast connection between electron temperature changes and changes of the film resistance and thus plays a minor role in the temporal evolution of the response. In accordance with experimental observations a two-component response was revealed from simulations. The slower component corresponds to a bolometric mechanism while the fast component is connected with the relaxation of the electron temperature. Calculated photoresponse transients are presented for different ratios of the electron and phonon specific heat, radiation pulse durations and fluences, and frequency band passes of registration electronics. From the amplitude of the bolometric component we determine the radiation energy absorbed in a film. This enables us to reveal an intrinsic electron-phonon scattering time even if it is much shorter than the time resolution of readout electronics. We analyze experimental voltage transients for NbN, YBa2Cu3O7, and TlBa2Ca2Cu3O9 superconducting films and find the electron-phonon interaction times at the transition temperatures of 17, 2.5, and 1.8 ps, respectively. The values are in reasonable agreement with data of other experiments.
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Notes Approved no
Call Number Serial 903
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Author Aksaev, E. E.; Gershenzon, E. M.; Gol'tsman, G. N.; Semenov, A. D.; Sergeev, A. V.
Title Interaction of electrons with thermal phonons in YBa2Cu3O7-δ films at low temperatures Type Journal Article
Year 1989 Publication JETP Lett. Abbreviated Journal JETP Lett.
Volume (down) 50 Issue 5 Pages 283-286
Keywords YBCO HTS films
Abstract The time of electron-phonon interaction tau(eph) in YBaCuO films at low temperatures is studied. This is measured as the time of resistance relaxation in the resistive state of the superconducter, and is also determined from the increase in resistance under the action of radiation. Consistent results of these methods show that resistance relaxation in the resistive state is caused by cooling of the electron subsystem with respect to the phonon subsystem. The time tau(eph) is found to be inversely proportional to the temperature and comes to 80 ps when T = 1.6 K and 5 ps when T = 30 K. 6 refs.
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Notes Approved no
Call Number Serial 1690
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Author Sergeev, A. V.; Semenov, A. D.; Kouminov, P.; Trifonov, V.; Goghidze, I. G.; Karasik, B. S.; Gol’tsman, G. N.; Gershenzon, E. M.
Title Transparency of a YBa2Cu3O7-film/substrate interface for thermal phonons measured by means of voltage response to radiation Type Journal Article
Year 1994 Publication Phys. Rev. B Condens. Matter. Abbreviated Journal Phys. Rev. B Condens. Matter.
Volume (down) 49 Issue 13 Pages 9091-9096
Keywords YBCO films
Abstract The transparency of a film/substrate interface for thermal phonons was investigated for YBa2Cu3O7 thin films deposited on MgO, Al2O3, LaAlO3, NdGaO3, and ZrO2 substrates. Both voltage response to pulsed-visible and to continuously modulated far-infrared radiation show two regimes of heat escape from the film to the substrate. That one dominated by the thermal boundary resistance at the film/substrate interface provides an initial exponential decay of the response. The other one prevailing at longer times or smaller modulation frequencies causes much slower decay and is governed by phonon diffusion in the substrate. The transparency of the boundary for phonons incident from the film on the substrate and also from the substrate on the film was determined separately from the characteristic time of the exponential decay and from the time at which one regime was changed to the other. Taking into account the specific heat of optical phonons and the temperature dependence of the group velocity of acoustic phonons, we show that the body of experimental data agrees with acoustic mismatch theory rather than with the model that assumes strong diffusive scattering of phonons at the interface.
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Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0163-1829 ISBN Medium
Area Expedition Conference
Notes PMID:10009690 Approved no
Call Number Serial 1648
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