Magnetic circular dichroism of CdTe nanoparticles

Magnetic circular dichroism (MCD) of water-soluble CdTe nanoparticles was observed in the visible spectral range for the first time. Diameter of nanoparticles varied from 2.3 to 4.5 nm. Absorption and photoluminescence spectra were also recorded. Absorption line at 19400 cm^?1 and luminescent line at 18200 cm^?1 were observed. Splitting of value 960 cm^?1 was revealed in the MCD spectrum. Approximately the same splitting was extracted from the absorption spectrum. The MCD was identified as the temperature independent paramagnetic mixing effect. Nature of the absorption line and of its splitting are discussed.     

Laser Raman Spectrum of Triglycine Sulfate

Abstract

The laser Raman spectrum of ferroelectric triglycine sulfate has been determined by the use of an argon ion gas laser. The observed Raman lines are compared with reported assignments in the literature by Taurel¹ and Krishnan², Determination of depolarization ratio of the sulfate line at 980 cm^?1 shows that the Raman band is highly polarizable and the molecular vibration is totally symmetrical v₁.

The role played by the glycine groups in the spontaneous polarization and its reversal can be indirectly confirmed by Raman spectrum of TGS. Interpretation of the Raman spectrum indicates that the SO₄ groups do not have tetrahedral symmetry at roan temperature. Ferroelectric behavior of TGS is attributed to the glycine groups.     

An Infrared Study of Conformational Isomerism in Cyclohexyl Iodide

Abstract

A comprehensive solvent, concentration, and temperature study has been made of the 850 to 400 cm^?1 region of the infrared spectrum of cyclohexyl iodide. This causes us to reject the assignment of Larnaudie and of Chiurdoglu and Reisse of v(C-I)_eq at 654 cm^?1 and v(C-I)^ax at 638 cm^?1, and to suggest that the two modes are almost coincident in n-hexane solution at 656.2 cm^?1 (eq) and 655.6 cm^?1 (ax).     

The high-resolution infrared spectrum of the 201 band of carbonyl fluoride: Determination of the far infrared laser frequencies

The first high-resolution (0.0024 cm^?1) spectrum of the 2₀¹ band of COF₂ at 963 cm^?1 is reported. Nearly 4000 rotational transitions have been observed and assigned in the band between 936 and 990 cm^?1. The line positions are estimated to be accurate to 0.0001 cm^?1 (relative). The spectrum was calibrated using two adjacent bands of OCS. Approximately 1560 infrared transitions have been fitted simultaneously with the previously reported microwave data. The wave numbers of far infrared laser lines recently observed by Tobin and by Temps and Wagner have been calculated from the 2¹ energy levels, with estimated uncertainties of between 10^?5 and 10^?6 cm^?1.     

The submillimeter-wave spectrum and spectroscopic constants of SO2 in the ground state

The submillimeter-wave spectrum of SO₂ has been recorded with 0.004 cm^?1 resolution in the region 8–90 cm^?1. About 2000 lines were observed, 1500 of which have been assigned to the ground state rotational transitions of ³²SO₂. Molecular constants up to the 10th order have been derived, combining our data with the available microwave data in the literature. SO₂ rotational spectrum line positions up to 90 cm^?1 can be reproduced from these constants, within the experimental accuracy (2 × 10^?4 cm^?1).     

Study of the ion mobility in a Li0.03Na0.97Ta0.4Nb0.6O3 solid solution by raman spectra

We have studied ion mobility in a Li_0.03Na_0.97Ta_0.4Nb_0.6O₃ solid solution by its Raman spectra. It has been revealed that, as the temperature of the solution is increased to approach the point of the phase transition to a state with a high conductivity with respect to lithium, the lines with frequencies at 77, 118, and 142 cm^?1, which refer, respectively, to librations of oxygen octahedra Nb(Ta)O6 as a whole and vibrations of Li and Na ions in octahedra, considerably broaden, decrease in intensity, and smear into the wing of the Rayleigh line. Remaining lines are preserved in the spectrum. We have observed that the width of the line with a frequency of 118 cm^?1 depends exponentially on temperature, while the width of the line with a frequency of 142 cm^?1 changes linearly with it, which makes it possible to attribute to the line with the frequency of 118 cm^?1 to vibrations of Li⁺ cations, whereas the line with the frequency of 142 cm^?1 should be attributed to vibrations of Na⁺ cations in AO₁₂ cuboctahedra. The average lifetime of Li⁺ ions in equilibrium positions and the jump barrier have been estimated to be ～8 × 10^?12 s and ～20 kJ/mol, respectively. This agrees well with the data in the literature on measurements of electric conductivity.     

Second order Raman spectrum and phase transition in InSe

The Raman spectrum of InSe was taken at room temperature and at liquid nitrogen temperature. We found that the TO (199 cm^?1) and LO (212 cm^?1) modes, together with their overtones and combinations at 400, 416 and 423 cm^?1 disappeared at lower temperatures. We attribute the vanishing of these modes at low temperatures to a change of phase from ? to β polytype.     

Line strengths of the ν1 + ν4 band of 12CH4

The line strengths of the ν₁ + ν₄ band of ¹²CH₄ at 4223.5 cm^?1 were measured using a leastsquares procedure that iterates between the observed spectrum and a synthetic spectrum calculated at correct instrumental and gas sample conditions. The methane spectrum was recorded at 0.011 cm^?1 resolution with signal-to-noise ratios of 300 to 1 or better using a Fourier transform spectrometer at Kitt Peak National Observatory. Line assignments were evaluated and extended to upper state J of 13. The observed line strengths reflect significant perturbation by other states so that only portions of the band can be used to determine a band strength of 6.92 (2) cm^?2 atm^?1 at 296 K with a Herman-Wallis factor of (1 – 0.0035(2)m)².     

Four-photon laser spectroscopy of liquid water and aqueous solutions of α-chymotrypsin in the range ±5 cm<Superscript>−1</Superscript>

The resonances located at 1.2, 1.6, 2.0, and 2.3 cm^?1 with a width of ～0.2 cm^?1 were observed for the first time in the range ±5 cm^?1 of the four-photon Rayleigh wing spectra of distilled water and aqueous solutions of the protein α-chymotrypsin. The line at 2.3 cm^?1 belongs to the rotational transition 3(2, 1)–4(1, 4) of the ground vibrational state of water. In the presence of the protein, the spectrum is modified by the appearance of new lines, located at 0.74, 2.8, and 3.2 cm^?1. The modification of the spectrum observed is interpreted as a manifestation of low-frequency vibrations of large molecular fragments in aqueous protein solutions and as a result of the structuring of water in the vicinity of protein molecules.     

Temperature Effect on the IR Absorption Spectra of Hydrogen Bonded (N[sbnd]…N)+ Homoconjugated Cations

Abstract

The effect of temperature on the absorption spectra from 50 to 3200 cm^?1 of a number of amine semiperchlorates and perchlorates of amines with two basic centres in which the hydrogen bridges (N [sbnd] H…N)⁺ are formed, was investigated. Three broad absorption regions may be distinguished in the spectrum, viz., between 100 and 900 cm^?1, 600 and 1800 cm^?1 and 1700 and 2900 cm^?1. The latter one may be assigned to the stretching vibration ν_S (N [sbnd] H…N).

A shift of this band peak (which is usually a doublet at room temperature for aromatic amines) towards longer wavelengths on decreasing the temperature may be an evidence that the bridge becomes shorter. Simultaneously with these changes, most salts under investigation exhibit a strong increase in low-frequency absorption intensity at about 400–600 cm^?1. It may be suggested that this absorption results from a transition between the split levels of the zero vibrational state.     

Vibronic spectra of matrix-isolated lead sulfide

Vibronic spectra are reported for lead sulfide in argon, krypton and SF₆ matrices at low temperatures. Emission stimulated by laser line irradiation of PbS is observed from the v′ = 0 level of three electronic states lying at about 14 500, 18 500 and 21 500 cm^?1 above the ground state. Emission is also observed from an excited state of Pb₂S₂ at about 17 000 cm^?1. In addition, the laser radiation gives rise to the vibrational Raman spectrum of PbS in argon at 423.2 cm^?1 and to a very weak Raman band at 297 ± 2 cm^?1 which we attribute to Pb₂S₂.The effects of temperature on the matrix spectra, of matrix material on the band origins, and of matrix concentration on the vibrational relaxation process, and the apparent degrees of coupling among the electronic states have all been examined. The electronic absorption spectrum of PbS in Ar is reported and the matrix data are compared with available information on gaseous PbS.     

Hard mode infrared spectroscopy of CaTiO3—CaFeO2.5 perovskites

Abstract

Powder-absorption infrared (IR) spectra of perovskites CaFe_xTi_1?x O_3?x/2 (0≤x≤1) annealed at different temperatures were investigated at room temperature in the range 135–2000 cm^?1. The spectra change as a function of composition, annealing temperature and structural state (order-disorder of oxygen vacancies). Autocorrelation analysis has been used to determine variations of average line widths of groups of peaks in the primary IR spectra. The band widths increase on increasing Fe content in the region of the structures with disordered oxygen vacancies and they decrease on going through the order-disorder boundary. High degrees of local structural heterogeneity are suggested by the effective line widths of the phases at intermediate compositions. The intensity of bands at ～150 and ～443 cm^?1 decreases with increasing Fe content in the compositional range of the disordered structures. Finally, for every annealing temperature, the frequency of the band at ～600cm^?1 systematically shifts to higher values on increasing Fe content, these values decreasing again for the fully ordered structures.     

The Electronic and Infrared Absorption Spectra of Toluene-d

Abstract

The infrared and ultraviolet absorption spectra of toluene-d have been investigated for the first time in the regions 400 - 4000 cm^?1 and 2350 ?2750 A° respectively. The intense band at 2666.3 A°(37494 cm^?1) in the u.v. vapour absorption spectrum has been identified as the o,o band and others have been interpreted in terms of the three (519,632 and 785 cm^?1) ground state and the six (454,526,743,935,963 and 1180 cm^?1 excited state fundamentals. The correlation of the various frequencies of the ground and excited states of toluene and toluene-d has been done. The observed isotopic shift for toluene-d is 14 cm^?1.     

Impurity induced far infrared absorption in doped NaCl and KCl

Far infrared absorption measurements with NaCl single crystals doped with AgCl and CuCl respectively show resonant band mode lines at 4.2 ?K at 52.5 cm^?1 and 23.6 cm^?1 respectively. Their measured halfwidths are 10 cm^?1 and 0.7 cm^?1 respectively. The halfwidth of the NaCl: Cu⁺ line increases strongly with increasing temperature. In NaCl:Mg⁺⁺, NaCl:Ca⁺⁺ and NaCl:Ag⁺ a temperature independent broad absorption is observed above 50 cm^?1, which behaves roughly as the density of phonon states in the unperturbed crystal. In KCl: Cu⁺ and KCl: Br^? a temperature independent absorption with a maximum at 108 cm^?1 is obtained corresponding to an expected region of high density.     

The Near Ultra-Yiolet Absorption Spectrum of Para-Fujoro Phenetole Vapour

Abstract

The near ultra-violet absorption spectrum of parafluoro phenetole has been studied in vapour phase. About 135 red degraded Bands have been measured. These have been explained in terms of five ground state (187, 258, 346, 633 and 855 cm¹) and seven excited state (151, 306, 527, 816, 966, 1279 and 1328 cm^?1) fundamental frequencies. A red shift of 1243 cm^?1 of (0,0) hand relative to that of Phenetole is also observed.     

Raman Spectrum of Chloromethyl Thiocyanate

Abstract

The liquid-state Raman spectrum was obtained for chloromethyl thiocyanate. The previously unobserved C-S-C bending band was observed at 188 cm^?1. The Raman spectrum supports the conclusion that only the C_S conformer is present.     

Raman spectrum of metallic layered compound NbSe2

Raman spectrum of layer-type compound NbSe₂ has been obtained at liquid nitrogen temperature. The frequencies of the Raman active modes E²_2g, A_1g and E¹_2g are measured to be 29.6 cm^?1, 230.9 cm^?1 and 238.3 cm^?1 respectively. The observed second order Raman spectrum of NbSe₂ is very different from the corresponding spectrum of MoS₂. These results show that the force constants of NbSe₂ are less anisotropic than those of MoS₂.     

The Electronic Absorption Spectrum of Hafnium Monochloride

Abstract

Intracavity laser spectroscopy has been applied for investigation of absorption spectrum of HfCl molecule. In the region 560–700 nm 59 bands have been obtained. Rotational structure analysis of 0–0 band indicated that Hund's case (c) of angular moment coupling applied to this molecule. The molecular constants (cm^?1) calculated for upper and ground electronic states are: ω′ = 353.05 cm^?1, ω″ = 379.65 cm^?1, B′=0.21486 cm^?1 B″ = 0.21801 cm^?1.     

IR Absorption and Raman spectroscopic study of reentrant-nematic liquid crystalline N-[4-(4-Octyloxy-benzoyloxy) Benzylidene]-4-Cyanoaniline (OBBC)

Abstract

The IR absorption and Raman scattering of OBBC have been investigated in the solid, ReN, SmA and nematic phases. The intensity of the 2229 cm^?1 band assigned to the C[tbnd]N stretching mode decreases with increasing temperature in the reentrant nematic phase; this is attributed to a change in the overlap of the molecules. While the IR bands at 1728 and 841 cm^?1 also show a remarkable temperature dependence, Raman bands do not show significant temperature dependence in the liquid-crystal phases.     

Vibrational spectroscopic characterization of the magnesium borate-phosphate mineral lüneburgite

ABSTRACT

Lüneburgite, a rare magnesium borate-phosphate mineral from Mejillones, Chile, has been characterized using Raman and mid-infrared spectroscopy methods. Boron tetrahedra are characterized by sharp Raman band at 877?cm^?1, attributed to the ν₁[BO₄]^5? symmetric stretching mode. The phosphate anion is associated with a distinct band at 1032?cm^?1, attributed to the ν₃[PO₄]^3? antisymmetric stretching mode. The most intensive Raman band at 734?cm^?1 is ascribed to stretching vibrations of bridging oxygen atoms in boron–oxygen–phosphor bridges. Bonds associated with water bending mode and stretching vibration are observed at 1661?cm^?1 (infrared) and in the 3000–3500?cm^?1 region (Raman and infrared spectrum).