Magnetothermal emf of p-InSb Samples with High Temperature Gradient upon Uniaxial Strain

Russian Physics Journal -     

High resolution X-ray diffraction studies at high pressures

Abstract

The principal sources of systematic error in high-pressure x-ray structure determination with a diamond anvil cell have been studied in detail. The results of these studies have been used to develop techniques to minimise or correct for these effects.     

New intraband magneto-optical studies on n-InSb

A highly sensitive photoconductive technique has been used to provide the first direct evidence of emission of five optical phonons during the energy relaxation process of the photoexcited electrons induced by a CO₂ laser in n-InSb. The CO₂ laser-induced magnetophotoconductivity exhibits a number of very sharp resonances whose positions depend strongly upon photon energy. All observed transitions can be described with one single set of band parameters.     

High resolution electronic band spectral studies of the GaI molecule

The emission band spectrum of the GaI molecule, lying in the region 3800–4200A and attributed to two overlapping transitions (A0⁺-X0⁺ and B1-X0⁺), has been studied under high resolution in the 3rd order of a 10.5 m Ebert grating spectrograph at a dispersion of 0.18/mm. Isotopic shifts of the ⁷¹GaI and ⁶⁹GaI molecules are calculated for various bands. They are found to agree with experimentally measured values, thereby confirming the vibrational assignments. The reversal of shading of various branches, belonging to one band and leading to the formation of extra heads, has been investigated. Making use of the rotational constants of the ground state (X0⁺) obtained from microwave spectral studies, the rotational constants of the excited A0⁺ and C1 states have been evaluated. Electronic configurations, potential energy curves and dissociation products are discussed.     

High performance latching-type luminescent magneto-optical photonic crystals

We report the properties of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals (MOPCs) composed of alternating quarter-wavelength layers of diamagnetic Sm(3)Ga(5)O(12) and MO-active Bi(2.97)Er(0.03)Al(0.5)Ga(0.5)O(12) garnets rf-magnetron sputtered on Gd(3)Ga(5)O(12) (111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure bismuth iron garnet. As a result, photonic crystals owned a record high magneto-optical quality and a latching-type (magnetic remnant) Faraday rotation (FR). At the resonance wavelengths 775(640) nm, a specific FR(θ)(F)=-14.1(14.8) deg/μm and MO-quality factor Q=99.3(46.2) deg represent the highest MOPC performance achieved so far.     

High resolution photoconductivity studies of residual shallow donors in ultrapure Ge

High resolution photoconductivity studies of residual shallow donors in ultrapure (n = 2 x 10¹⁰cm^-3) germanium have revealed absorption corresponding to transitions to higher lying levels not previously observed because of spectrometer limitations and/or line broadening due to impurity-impurity interactions. In this paper we list the results of our studies of four residual donors in high purity material, compare these results with a theoretical calculation for higher lying energy level spacings, and examine the temperature dependence of the two step photothermal photoconductivity process.     

High resolution X-ray studies of porous PbTe layers on silicon substrates

The structure of PbTe films after anodic electrochemical etching in Norr electrolyte is studied by high resolution X-ray diffractometry and reflectometry. Lattice defects before and after etching are estimated. The quantitative parameters of the pores are determined. The advantage of the complex application of high resolution X-ray methods for the determination of the real structure of lead-telluride porous films is shown.     

ac Impurity hopping conducting in p-InSb

We report the first measurement of the ac conductivity of p-InSb at low temperatures in the fréquency range 10 −10¹⁰ Hz. The conductivity has been determined from the gathering of three sets of data, the dc conductivity curve, the conductivity data obtained from an ultrasonic experiment and the microwave conductivity. Frequency effects have only been observed in the hopping conduction regime. It was found that the ac conductivity varies as ω (S=0.75). The results are discussed in relation with the single-phonon hopping theory.     

High time resolution spectroscopy studies of the explosive decomposition of silver azide

We have analyzed the existing assumptions about the mechanism of the explosive decomposition of the heavy metal azides. We present here a study of the kinetics of the explosive decomposition of silver azide, initiated by a laser pulse. New effects are identified and studied, including a pre-explosion conductivity and luminescence. On the basis of our results, we conclude that the reaction proceeds by a chain reaction mechanism. In terms of band theory, we propose a model of the primary chain step of the reaction as the creation of a quasilocalized state deep in the valence band with two holes localized at a defect (N₃ ⁰), with impact ionization occurring as they “float up”. State University, Kemerov. Translated from Ivvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 162–175, November, 1996.     

High field magneto-optical study of yttrium iron garnet (YIG)

The temperature (5–300 K) and field (0–100 kG) variation of the Faraday rotation of yttrium iron garnet single crystals has been measured at selected wavelengths in the range 0.8–1.6 μm. Above the magnetic saturation field of a few kG the Faraday rotation is found to decrease with increasing field for all temperatures and wavelengths. It is shown that a field dependence of the magneto-optical coefficients causes this surprizing effect.     

High resolution electron energy loss spectroscopy surface studies of hydrogenated detonation nano-diamond spray-deposited films

Nano-diamond films composed of 3–5 nm grains prepared by the detonation method and spray deposited onto silicon substrates were examined by high resolution electron energy loss spectroscopy (HR-EELS), Raman spectroscopy and transmission electron microscopy. The HR-EEL spectrum of the annealed and hydrogenated films displays dominant C–H losses at 360–365 meV; the diamond optical phonon and its overtones. These results suggest that the films reveal well defined hydrogenated diamond surfaces on the nanometric scale. Detailed analysis of the diamond optical phonon overtone revealed a red-shift of the basic C–C vibration by 5 meV. We attribute this shift to a phonon quantum confinement effect detected by HR-EELS spectroscopy.     

Optical phonon assisted cyclotron harmonic transitions in p-InSb

The observation of optical-phonon induced cyclotron resonance harmonics in the valence band of InSb is reported. A photoconductivity technique was applied, using a CO₂ laser and magnetic fields up to 15 T. The observed resonances are well described by a corrected Pidgeon-Brown model calculation which is also consistent with experimentally observed magneto-optical intra-conduction and interband transitions.     

High resolution digital holography

In digital Fresnel holography, present specifications of charge-coupled device cameras require the incident beams to be quasi-parallel. That implies large speckle grain size and low lateral resolution in reconstructed images. Better lateral resolutions are demonstrated in our work, down to 8 μm, allowing the observation of sub-millimetre objects by digital holography. The experimental set-up built samples the incident light distribution with a definition of 500 pixels mm⁻¹. The maximum acceptable angle is then widened and the hologram recording and reconstruction distances are drastically reduced, as well as the speckle size. Interferometric holography was implemented for the measurement of the deformation of a sub-millimetre silicon cantilever and results in phase-contrasts imaging are also reported. The design of dedicated complementary metal-oxide-semiconductor active pixel sensor cameras is also discussed.     

High resolution spectroscopy of and

Extensions in frequency coverage coupled with sensitive spectroscopic techniques have enabled high resolution measurements of pure rotational spectra of deuteromethane and its 13-C substituted counterpart up to J^′=7. The current work reveals a small inconsistency in previously reported frequency measurements of ¹²CH₃D at J^′=5.     

High resolution NEXAFS studies of aromatic molecules adsorbed and condensed on Ni(111)

High resolution near-edge X-ray absorption fine structure measurements have been performed on benzene, pyridine and pyrazine adsorbed and condensed on Ni(111). The carbon K-edge multilayer data show the splitting of the e_2u level of benzene into b₁ and a₂ levels for pyridine and into b_3u and a_u levels for pyrazine; the corresponding π resonances are asymmetric due to the vibrational fine structure. At the nitrogen K-edge the transitions into the a₂ and a_u levels are not observed. The benzene data suggest that the Rydberg orbitais are quenched in the condensed phase and that the broad structure above a photon energy of ~ 300 eV is made up of (at least) two σ resonances. On adsorption the π resonances are considerably broadened at the adsorption edges of atoms which interact strongly with the substrate.     

High resolution infrared spectroscopic studies of ethylene-1,1-D2

Rotational assignments in the ν₆ + ν₉ type-A band and the ν₉, ν₆ + ν₁₁, and ν₁ + ν₆ type-B bands of ethylene-1,1-D₂, recorded at a resolution of ～0.03 cm^?1, enable the ground state rotational constants to be determined much more accurately than previously. A significant change in the A₀ constant is noted. All upper states suffer perturbations to their rotational structures. Analyses, excluding the areas of perturbation, still enable the excited state constants to be determined with considerable precision.     

High resolution spectroscopy using photodeflection

Isotope separation by laser deflection of an atomic beam, combined with simultaneous mass spectroscopy, has been used to determine optical frequency shifts and to assign mass numbers to all components of the $\text{Ba 6s}{}^2{}^1\text{S}{}_0\text{?6s6p}{}^1\text{P}{}_1$ 5536 Å resonance. Several components which cannot be resolved optically without the use of enriched samples, were resolved with the technique described. They are ${}^{135}\text{Ba}\text{(F=}\text{5}\text{2}\text{)}$ at 120 MHz, ¹³⁶Ba at 128 MHz and ¹³⁴Ba at 138 MHz.     

Observation of magnetic field dependent ultrasonic relaxation time in p-InSb

Ultrasonic attenuation and sound velocity measurements are presented for p-InSb (≈ 10¹⁴cm^?3) at low temperatures in high magnetic fields. A magnetic field dependent relaxation time is observed, which is interpreted as being due to a relaxation process via holes in the valence band.