TE Spectra Research Articles

TE and TM modes in gyrotropic waveguides

An exact analysis of propagation in a gyroptropic waveguide is presented for the special case of the DC magnetic field normal to the direction of propagation and tangential to the plane of the film; this is found to support pure TE and TM modes. Expressions for the propagation constants in terms of the permittivity tensor elements are derived. The TM modes depend on the off-diagonal element and one of the diagonal elements, while the TE modes depend only on the second diagonal element. Numerical results computed for a YIG film on a GGG substrate show that the effect of the off-diagonal element is negligible but any difference in the value of the diagonal elements affects significantly the relation between the TE and TM mode spectra.

Electronic structure of trigonal and amorphous Se and Te

The electronic structure of trigonal and amorphous Se and Te is investigated using the empirical pseudopotential method (EPM), charge-density calculations, and simple tight-binding models. Band structures and electronic densities of states are obtained which are in excellent agreement with recent photoemission measurements. The tight-binding models are used to obtain analytic expressions for the energy bands and to interpret the EPM band structures in terms of real-space orbital-orbital interactions. Charge-density calculations obtained as a function of energy and evaluated within specific energy intervals are used to interpret various structure in the density of states. Specifically certain easily resolvable peaks in the experimental photoemission spectra are associated with intrachain and interchain localized states, respectively. By taking only short-wavelength components of the charge density, a bonding charge can be defined which gives an estimate of the intrachain vs interchain bonding strengths. The trigonal results along with model calculations to investigate the effects of bond-angle variations on chains and the presence of eight- and six-fold rings of bonds are used to interpret the changes observed in the experimental spectra of amorphous Se and Te. A new model of amorphous Se is proposed.

Asymmetry in the 125Te Mössbauer Spectra of Tellurium Thiourea Complexes: Sign of the Nuclear Quadrupole Moment of the 3/2 State

Asymmetry in the Mössbauer spectra of Te(II) thiourea complexes is shown to be due predominantly, if not exclusively, to single crystal orientation effects. The asymmetry in TeTu4Cl2•2H2O is consistent with a negative sign for the nuclear quadrupole moment of the [Formula: see text] excited state in 125Te.

High-Resolution X-Ray-Photoemission Spectra of PbS, PbSe, and PbTe Valence Bands

High-resolution x-ray-photoemission valence-band spectra (0-45 eV binding energy) of cleaved single-crystal PbS, PbSe, and PbTe are reported. The spectra are compared with available band-theory results. Relativistic orthogonalized-plane-wave results exhibit the best over-all agreement with experiment. Empirical-pseudopotential-method (EPM) results show similar agreement for all but the most tightly bound valence band. The uppermost peak, corresponding to the three least tightly bound bands, shows detailed structure in good agreement with the EPM predictions. The PbTe valence-band spectrum can be synthesized from the x-ray-photoemission valence-band spectra of Pb and Te.

Te 125 Mössbauer effect study of neutron capture effects in PbTe, Te and TeO 2

The Mössbauer emission spectra of Te 125 in PbTe, Te metal, and TeO 2 have been measured following neutron capture in Te 124. Mössbauer data for each sample were taken after the source irradiation and following thermal annealing. The irradiation conditions were chosen so that only the thermal neutron capture induced defects should have a significant effect on the environment of the Mössbauer emitting nuclei. Comparison of the data taken before and after the source annealing showed no differences in linewidth, isomer shift, quadrupole splitting, or resonance intensity within the standard deviations of the parameters. The results show that the thermal neutron capture process in Te 124 does not affect the Te 125 Mössbauer spectra. The possible reasons for this are discussed. The results also indicate that the anomalous isomer shift reported by Stepanov and Aleksandrov in a similar experiment on PbTe is probably caused by a high background of fast neutron induced displacements.

The Reflection and Transmission of Infrared Materials V: Spectra from 2 μ to 50 μ

Reflection and transmission spectra of BN, CdS, Irtran 6, GaSb, GaAs, GaP, InSb, InAs, InP, RbBr, RbCI, RbI, SrTiO(3), and Te are presented from 2 micro to 50 micro.

Infra-red lattice bands of trigonal tellurium and selenium

The room temperature reflectivity spectra of trigonal Te and Se have been fit using a harmonic oscillator formalism. The effective charge associated with the infra-red active lattice modes is high (∼ 0.15 e to 2.2 e) and is attributed entirely to charge redistribution effects. A calculation of the polaron coupling constants for Te and Se indicates that polar mode scattering is important in room temperature transport phenomena.

Metal–halogen vibrations of simple octahedral ions containing tin, selenium, and tellurium

The position of the infrared-active fundamentals for some hexahalogeno-stannate, -selenate, and -tellurate ions are presented, and correlations are estabilished for metal–halogen stretching and bending modes. This is the first time the infrared spectra of Te–Cl,Te–Br, or Te–l bonds have been reported. The effect of the extra pair of electrons on the positions of the fundamentals is discussed for the Se(IV) and Te(IV) complexes, and their spectra are also examined for small deviations from cubic symmetry. The hexaiodoselenate complex has not been reported previously, and the positions of the absorption bands reflect the weakness of the selenium–iodine bond.

The Mössbauer effect in Te 125

The Mossbauer absorption spectra of Te/sup 125/ 35.5-kev obtained using Pb- Te, the spectrum of which is an unsplit line. The spectra show marked asymmetry with different right to left intensity ratios for crystalline and amorphous Te. The imorphous and metallic Te spectra are resolvable into two lines, in agreement with the quadrupole splitting of the 3/2 level. Four lines due to two crystal modifications appear in the TeO/sub 2/ spectrum. The splittings for Te metal and oxide agree with Frankel's values. (D.C.W.)

(n, d) and (n, p) Reactions nearZ=50

An emulsion study is reported of charged particles produced by 14-Mev neutron bombardment of ${\mathrm{Rh}}^{103}$, ${\mathrm{In}}^{115}$, ${\mathrm{Sn}}^{116}$, ${\mathrm{Sn}}^{120}$, Sb, and Te. For all but Te (no detectable yield) cross sections and spectra are presented, with distributions over the first 40\ifmmode^\circ\else\textdegree\fi{} of laboratory angle of energy groups from Rh, In, and Sb. Contrary to an assumption common in earlier work, there is strong evidence that the ($n, d$) reaction contributes strongly. Five peaks among the Rh, In, and Sb spectra are identified with pickup transitions, the angular distributions conforming to Butler curves for uniquely predicted (2) or reasonable (3) $l$ values. These values are consistent with target proton orbitals in all five cases. The wide ($n, \mathrm{np}$) group is found at the expected energy in the Rh, In, ${\mathrm{Sn}}^{116}$ and Sb spectra; its angular distribution is anomalous for Rh but displays the expected isotropy in the other three cases. Up to at least 6-Mev excitation the ($n, p$) gross structure is dominated by single-particle effects, the uncontaminated ($n, p$) yield obeying predictions of the Nilsson model as to spectral concentration and angular distribution; the low collective levels excited in ($p, {p}^{\ensuremath{'}}$) are not observed. Systematic behavior of the direct-interaction radius for ($n, d$) and ($n, p$) and of the reduced width for pickup are found to be reasonable. It is inferred that the parent state for proton pickup with low residual excitation is almost purely a single-particle state in the case of Sb, and has a strong single-particle character in Rh and a very weak one in In.