Far-infrared reflection spectra of SmS polycrystals

The reflection spectra of polycrystalline SmS samples have been measured in the far-infrared region within a broad temperature interval (293?C80 K). Such measurements have been demonstrated to be efficient in the determination of the gradient in free electron concentration, an important aspect for the estimation of the magnitude of the thermovoltaic effect in a sample.     

ZnSe-ZnTe应变层超晶格远红外反射谱

本文首次报道室温下测量的分子束外延生长的ZnSe-ZnTe应变层超晶格的远红外反射谱.得到了ZnSe、ZnTe横光学声子摸.用长波长超晶格介电理论和多层吸收薄膜理论进行曲线拟合,确定Ⅱ-Ⅵ族ZnS、eZnTe材料的一些基本材料参数,如横光学声子频率、模衰减常数、模振荡强度、高频介电常数等.本文首次报道这些参数.     

Far-infrared spectra of color centers in alkali halides

Abstract

In this paper we wish to review some recent results on the effects of color centers on the vibrational properties of alkali halide crystals.     

Far-infrared spectra of dysprosium doped yttrium aluminum garnet nanopowder

The solution combustion synthesis was used to prepare nanopowders of yttrium aluminum garnet (YAG) and YAG doped with dysprosium ions, Dy³⁺, (YAG:Dy). The morphology, specific surface area, texture, and optical properties of the prepared materials were studied by the means of scanning electron microscopy (SEM), nitrogen adsorption method, and far-infrared spectroscopy at room temperature in the spectral region between 80 and 600 cm⁻¹. It was established that all the examined samples were microporous. The Maxwell–Garnet formula was used to model dielectric function of YAG and YAG:Dy nanopowders as mixtures of homogenous spherical inclusions in air.     

Optical reflection spectra of cadmium halides

The reflection spectra have been measured at liquid helium temperature in the region 4–11.5 eV for CdCl₂ and CdBr₂ crystals. Exciton bands observed around the optical gap are associated with the halogen ion excitation under the influence of the strong crystal field. Characteristic sharp lines are also observed in the deep interband energy regions.     

Far-infrared spectra of ring compounds. XII. Far-infrared spectra,ring-puckering vibration,and molecular conformation of some analogs of bicyclo(3.1.0.)hexane

The far-infrared spectra of bicyclo(3.1.0.)hexane, 3-oxabicyclo(3.1.0.)hexane, and 3,6-dioxabicyclo(3.1.0.)hexane exhibit series of Q branches in the frequency range 250–125 cm^?1, like those observed for 6-oxabicyclo(3.1.0.)hexane (cyclopentene oxide) by Carreira and Lord (J. Chem. Phys.51, 2735 (1969)). The Q branches are interpreted as single quantum jumps of a one-dimensional ring-puckering vibration governed by a potential function of the form V(cm^?1) = A(Z⁴ + BZ² + CZ³), where Z is a reduced ring-puckering coordinate.The potential parameters for bicyclo(3.1.0.)hexane are A, 24.31 cm^?1; B, 26.67; C, 9.63; for 3-oxabicyclo(3.1.0.)hexane, 27.77 cm^?1, 20.63, 7.84; and for 3,6-dioxabicyclo(3.1.0.)hexane, 25.25 cm^?1, 17.23, 7.33. They were determined by an iterative least-squares fit to the observed four, seven, and nine Q branches, respectively. These potential functions all have only a single minimum, implying a single stable conformation. The dipole moment, μ_rms, for 3,6-dioxabicyclo(3.1.0.)hexane in benzene solution was determined to be 2.50 D, clearly indicating that the stable conformation is the boat form. The boat conformation had been determined to be the stable form for cyclopentene oxide from a microwave study by Lafferty (J. Mol. Spectrosc.36, 84 (1970)). There is no direct evidence for the preferred conformation of the remaining two molecules but consideration of torsional interactions about the 1–2 and 4–5 bonds as well as the similarity of the spectra and potential functions for these molecules suggests that the boat conformation is the stable form of all of these molecules.     

Far-infrared rotational spectra of some freons; chlorotrifluoromethane,dichlorodifluoromethane, and trichlorofluoromethane

The far-infrared rotational spectra of chlorotrifluoromethane, dichlorodifluoromethane, and trichlorofluoromethane have been observed with an interferometric (Fourier transform) spectrometer in the region 10–40 cm^?1 at a resolution of 0.07 cm^?1. CCl₂F₂ exhibits a continuum spectrum at this resolution, but symmetric top rotational fine structure is observed for CClF₃ and CCl₃F. Isotope splitting is also observed in CClF₃, and analysis yields the rotational constants for C³⁵ClF₃ of B₀ = 0.11112 cm^?1, D_J = 1.6 × 10^?8cm^?1; and for C³⁷ClF₃, B₀ = 0.10835 cm^?1, D_J = 1.5 · 10^?8cm^?1. Isotopic shifts can be allowed for in CCl₃F to yield constants for C³⁵Cl₃F of B₀ = 0.0821 cm^?1, D_J = 1 × 10^?8cm^?1. These values are all in agreement with those deduced from microwave studies of the low J transitions apart from B₀ for C³⁵ClF₃, where the difference is outside the expected experimental error.     

Far infrared reflection spectra in narrow-gap semiconductors

Far infrared reflection spectra of Cd_XHg_1–X Se are measured in the region 20 to 600 cm^–1 at temperatures between 5 and 77 K. Reflection spectra are explained well by the dynamic dielectric function which is constructed as a sum of ₈–₈ interband, intraband and phonon contributions. The plasmon-LO phonon coupling effect is also discussed.     

Far-infrared spectra and barriers to internal rotation of isopropyl alcohol and alkyl mercaptans

Far-infrared spectra of isopropyl alcohol, ethyl mercaptan, isopropyl mercaptan, tert-butyl mercaptan, and their deuterated analogs have been examined. The observed torsional transitions are interpreted with a potential function of the form $\text{V =}\text{1}\text{2}\text{Σ}{}_{\mathrm{k}}\text{V}{}_{\mathrm{k}}\text{(1 ?}\text{cos}\text{kα)}$. The obtained energy differences are in good agreement with those determined from calorimetric data. The coupling of torsional vibration with other low frequency vibrations is discussed.     

Far-infrared and Raman spectra of KD2PO4

The far-infrared and the Raman spectra of KD₂PO₄ were measured for B₂ symmetry in the paraelectric phase and for A₁ symmetry in the ferroelectric phase. The results were discussed in comparison with those of KDP.     

Oriented ZnO nanorods and their IR reflection spectra

Oriented ZnO nanorods have been grown on sapphire and silicon substrates by pulsed laser deposition. It is established that IR spectroscopy gives information about the crystal structure of nanorods, their conductivity, and degree of orientation, depending on the growth conditions. A size effect is found: softening of optical ZnO phonons with a decrease in the nanorod diameter.     

On phase-amplitude correlation in reflection spectra of Fabry-Perot Interferometers

The correlation between the spectra of phase and reflection of free and fixed Fabry-Perot interferometers is theoretically studied. It is shown that, under certain conditions, the phase of the reflected wave can be determined directly from the reflection spectra.     

鲜红斑痣光动力治疗中皮肤光谱特点的变化

尝试利用漫反射光谱和荧光光谱检测鲜红斑痣皮肤在光动力治疗中的变化特点,用于分析治疗中组织光学特性的变化,指导光剂量的制定.在光动力治疗中,采用微型光纤光谱仪监测PWS皮肤的漫反射光谱和荧光光谱,结合PWS结构特点以及皮肤中主要吸光基团的吸收光谱,分析术中、术后相关组织成分变化及对应的光学特性变化.PDT治疗中PWS皮肤...