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Author Gershenzon, Ye. M.; Goltsman, G. N.; Yelantyev, A. I.; Petrova, Ye. B.; Ptitsina, N. G.; Filatov, V. S.
Title Lecture demonstrations of properties of superconductors and liquid helium Type Journal Article
Year 1987 Publication USSR Rept Phys. Math. JPRS UPM Abbreviated Journal USSR Rept Phys. Math. JPRS UPM
Volume 24 Issue 7 Pages 51
Keywords demonstrations, lections
Abstract New demonstrations for low temperature physics courses are described. Two transparent Dewar vacuum flasks fitting one inside the other with the external flask for nitrogen and the internal flask for helium are used. The helium temperature can be regulated in the 4.2 to 1.6 K range and the effects of reducing helium to the superfluid state at 2.17 K can be shown: boiling abruptly stops and superfluid flow appears. In order to show the electric and magnetic characteristics of superconductivity, a superconducting NbTi solenoid containing nonsuperconducting wire and germanium and superconducting Nb materials with different critical temperatures is placed in the helium refrigerant vessel. The fall of the resistance at the critical temperatures can be shown. In order to show magnetic field and superconductive current flow properties a shunt of superconductive material is connected in parallel to the coil and is enclosed in a teflon container with a heater which can vary its temperature. When it is heated and not superconductive, magnetic field effects can be demonstrated and when it is unheated and superconducting a continuous current can be demonstrated.
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Call Number Serial 1704
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Author Gol'tsman, G. N.; Gusinskii, E. N.; Malyavkin, A. V.; Ptitsina, N. G.; Selevko, A. G.; Edel'shtein, V. M.
Title The excitonic Zeeman effect in uniaxially-strained germanium Type Journal Article
Year 1987 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP
Volume 65 Issue 6 Pages 1233-1241
Keywords Ge, Zeeman effect
Abstract We have carried out a high-resolution spectroscopic study of the absorption of submillimeter radiation by free excitons in germanium compressed along the [ 1 11 ] axis in a magnetic field parallel to the compression axis. In particular, we studied the splitting of the 1s- 2p transition in fields up to 6 kOe at T = 1.6 K, and observed a complex pattern in the Zeeman splitting which we believe is related to the effect of thermal motion of the excitons in a magnetic field on their internal structure (the magneto-Stark effect). The calculated submillimeter spectrum of excitons agrees with the experimental data. We predict that in a magnetic field the energy of the 2p, term is a minimum at a finite value of the exciton momentum perpendicular to the field-that is, the energy minimum forms a ring in momentum space. It follows that the density of states for this term must be a nonmonotonic function of the energy. A theory is developed of analogous phenomena in positronium.
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Call Number Serial 1705
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.; Riger, E. R.
Title Effect of electron-electron collisions on the trapping of free carriers by shallow impurity centers in germanium Type Journal Article
Year 1986 Publication Sov. Phys. JETP Abbreviated Journal Sov. Phys. JETP
Volume 64 Issue 4 Pages 889-897
Keywords Ge, trapping of free carriers
Abstract Cascade Auger recombination of free carriers on shallow impurities in Ge is investigated under quasi-equilibrium conditions (T= 2-12 K) and in impurity breakdown. The Auger capture cross sections are found to be a,= 5. 10-l9 T-'n cm2 for donors and uip= 7- T-5p cm2 for acceptors. It is shown that in an isotropic semiconductor (p-Ge) ui is well described by the cascade-capture theory that takes into account only electron-electron collisions. In an anisotropic semiconductor ui is considerably larger (n-Ge, strongly uniaxially compressedp-Ge). Under impurity breakdown conditions the electron-electron collisions determine the lifetimes of the free carriers only in samples with appreciable density of the compensating impurity (Nk loi3 cmP3).
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Call Number Serial 1707
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Author Gershenzon, E. M.; Gol'tsman, G. N.; Ptitsina, N. G.
Title Observation of the free-exciton spectrum at submillimeter wavelengths Type Journal Article
Year 1972 Publication JETP Lett. Abbreviated Journal JETP Lett.
Volume 16 Issue 4 Pages 161-162
Keywords Ge, energy spectrum, free excitons
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Call Number Serial 1736
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Author Gershenson, E. M.; Gol'tsman, G. N.; Elant'ev, A. I.; Kagane, M. L.; Multanovskii, V. V.; Ptitsina, N. G.
Title Use of submillimeter backward-wave tube spectroscopy in determination of the chemical nature and concentration of residual impurities in pure semiconductors Type Journal Article
Year 1983 Publication Sov. Phys. Semicond. Abbreviated Journal Sov. Phys. Semicond.
Volume 17 Issue 8 Pages 908-913
Keywords BWO spectroscopy, pure semiconductors, residual impurities
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Notes Применение субмиллиметровой ЛОВ спектроскопии для определения химической природы и концентрации примесей в чистых полупроводниках Approved no
Call Number Serial 1714
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