Pressure broadening and shifting parameters for the spectral lines in the first overtone vibration-rotation bands of HBr and HI in mixtures with rare gases

We present experimental data on the previously unknown line broadening and shifting coefficients in the (2 ← 0) overtone vibration-rotation bands of the HBr and HI molecules in mixtures with several rare gases. The vibrational dependence of the isotropic and anisotropic components of the binary interaction potential is probed by separating the measured line shifts into parts symmetric and asymmetric in the line number m and by comparing with the previously published similar data for the fundamental bands of the same molecules. It is shown that the line shifts are dominated by the vibrational dependence of the isotropic potential. A linear correlation is found between the asymptotic values of the symmetric shifts in the overtone bands for all HX-Rg (X = F, Cl, Br, I) pairs and the respective C₆ long-range potential energy constants. Line broadening parameters in the overtone band of pure HBr are also reported.     

He-broadening and shifting coefficients of HCl lines in the (1←0) and (2←0) infrared transitions

ABSTRACT

We report experimental results on the broadening and shifting coefficients in a large interval of J quantum numbers in the fundamental and first overtone vibration–rotation bands of the HCl molecule in mixtures with helium. Many of the values, especially for the overtone transition, are novel. The uncertainties for the isotope-averaged broadening coefficients amount to 2% on average for the fundamental and 1.5% for the overtone bands. Shifts have a typical uncertainty of 3%.     

Pressure broadening and shifting parameters for the spectral lines in the fundamental vibration-rotation bands of HBr and HI in mixtures with rare gases

We report measurements of the line broadening and shifting coefficients in the (1 ← 0) fundamental absorption bands of the HBr and HI molecules in mixtures with rare gases He, Ne, Ar, Kr, and Xe. Comparison is given with the published data on other HHal-Rg systems. The measured line shifts are separated into terms symmetric and asymmetric in the line number m. The magnitudes of the symmetric shifts change in a regular manner in the series of rare gases and reach perturber-specific asymptotic values at higher ∣m∣. It is found that the asymptotic values of the symmetric line shifts linearly correlate with the respective C₆ potential energy constants and that the slopes of these correlations are proportional to the vibrational ground state dipole moments squared of the hydrogen halide molecules.     

Spectral line parameters in the (2 ← 0) overtone band and the dipole moment function of the HI molecule

We present here new high-resolution experimental data on the linestrengths and pressure-broadened Lorentzian widths for the P₂(13) to R₂(12) vibration-rotation lines in the first overtone absorption band of hydrogen iodide. By combining the measured linestrengths with our previous results for the fundamental band [J. Mol. Spectrosc. 218 (2003) 75] and with other published data for the higher-overtone bands of this molecule, an improved dipole moment expansion as a function of the dimensionless reduced nuclear displacement x is obtained: μ(x)=0.4471(5)−0.0772(2)x+0.542(3)x²−1.90(2)x³. This experimental dipole moment function is compared with the results of a few recent non-relativistic and relativistic ab initio calculations. The agreement between theoretical and experimental Herman-Wallis coefficients for the first two vibrational bands of HI is found best as ever reported before.     

Infrared study of the lattice vibrations in CuInS2

Infrared reflectivity and absorption spectra of CuInS₂ are measured in the wave-number range from 180 to 700cm^–1for the polarization directions perpendicular and parallel to the tetragonalc axis of the crystals. The optical dispersion parameters of the fundamental lattice modes are determined for both polarization directions and compared with previously published data. All the structures observed in the absorption spectra in the wavenumber range beyond the fundamental lattice bands can be interpreted in terms of two-phonon combination modes due to zone-centre phonons.     

Multiple inelastic electron scattering processes in thin molecular films: a simple model

Electron energy loss spectra of multilayer molecular films contain bands resulting from inelastic collisions at two or more sites within the film. The contributions of twofold loss processes are analysed for selected vibrational spectra of benzene and SF₆ using a simple model that was suggested previously and is extended here. It is shown that this analysis can be used not only to detect dipole scattering contributions to particular vibrational excitations. Combined with an estimate of the twofold loss spectrum based on the pattern of the fundamental bands the model also enables the identification of overtone and combination bands which is important for the detection of resonant processes.     

Forbidden transitions in homopolar isotopically unsymmetric diatomic molecules and the dipole moment of HD

The theoretical expressions for the intensities of forbidden rotational and rotation-vibration spectra of homopolar isotopically unsymmetric diatomic molecules, made allowed by the breakdown of the Born-Oppenheimer approximation, are derived. The results are applied to HD and it is shown that among the previously overlooked contributions to the dipole moment of the molecule there is one with a very significant value in the direction H^?D⁺. A rotationally dependent contribution arising from centrifugal distortion is extremely small. The intensities of the fundamental and overtone bands of HD are also considered.     

Simultaneous Analysis of the Rovibrational Levels upsilon(4)=1, 2, and 3 of HCCI and DCCI Based on Infrared Spectra

The energy levels upsilon(4)=1, upsilon(4)=2, and upsilon(4)=3 of DCCI have been analyzed by using the fundamental nu(4)(1) (470-520 cm(-1)) and the overtone 2nu(4)(0) (955-1005 cm(-1)) bands together with the hot bands 2nu(4)(0,2)<--nu(4)(1), 3nu(4)(1,3)<--2nu(4)(0,2), and 3nu(4)(1)<--nu(4)(1). In the case of HCCI the previously studied hot bands connected to nu(4) have been completed by adding 3nu(4)(1)<--nu(4)(1) into the analysis. The various l-type resonances have been taken into account in the analyses of both the isotopomers. Furthermore, the Coriolis resonance between the close-lying nu(3) and nu(4) of DCCI has been considered. Altogether, accurate values for the molecular constants and the resonance parameters have been obtained from simultaneous analysis and they have been compared with those from separate analyses for different levels. Copyright 2001 Academic Press.     

Vibrational spectra of chloroform, freon-11 and selected isotopomers in the terahertz region

The fundamental bands of the CCl₃ asymmetric deformation modes of selected isotopomers of chloroform (CHCl₃) and freon-11 (CFCl₃) have been measured in a static cell at ambient temperature using a laser-based source of tunable radiation in the terahertz region of the electromagnetic spectrum. The analysis of the rotational contours of the bands enabled the derivation of the fundamental frequencies with an accuracy of better than 3 GHz.     

Electronic,optical and bonding properties of MgCO3

The electronic, optical and bonding properties of MgCO₃ (magnesite, rhombohedral calcite-type structure) are calculated using a first-principles density-functional theory (DFT) method considering the exchange-correlation function within the local density approximation (LDA) and the generalized gradient approximation (GGA). The indirect band gap of magnesite is estimated to be 5.0 eV, which is underestimated by ～1.0 eV. The fundamental absorption edge, which indicates the exact optical transitions from occupied valence bands to the unoccupied conduction band, is estimated by calculating the photon energy dependent imaginary part of the dielectric function using scissors approximations (rigid shift of unoccupied bands). The optical properties show consistent results with the experimental calcite-type structure and also show a considerable optical anisotropy of the magnesite structure. The density of states and Mulliken population analyses reveal the bonding nature between the atoms.     

Eu<Superscript>3+</Superscript> doped yttrium oxysulfide quantum structures—structural,optical and electronic properties

Small particles of trivalent europium doped yttrium oxysulfide nanocrystals (ϕ ∼ 7 nm) were synthesized using sol–gel polymer thermolysis. The nanocrystals show significant change in the excitation bands corresponding to fundamental absorption and charge transfer absorption bands. The optical spectra essentially comprise of two parts: fundamental absorption (∼260 nm) and Eu³⁺–X²⁻ ligand (O²⁻/S²⁻) charge transfer (∼290 nm) bands. They show significant blue shifts (0.24–0.30 eV), respectively, with respect to the bulk counterpart. These may be explained by considering possible size dependent changes associated with quantum confinement effect in this large bandgap semiconductor system. FT-IR spectra revealed the difference in chemisorbed species between bulk and nanocrystalline samples. The results of the solid-state photo-induced electrical impedance spectroscopy studies are reported.     

Investigation of collision-induced absorption in the vibrational fundamental bands of O2 and N2 at elevated temperatures

Collision-induced absorption has been measured for the vibrational fundamental bands of N₂ and O₂ at temperatures up to 360 K. These data when combined with previously obtained lower temperature data show that the integrated band intensity of the O₂ fundamental increases as the temperature is raised above 300 K. The integrated intensity of the N₂ band also increases, but at a much lower rate with temperature.     

Synchrotron reflectivity spectrum, characteristic electron losses, and electronic structure of TlCl crystals

Spectra of two complete sets of TlCl fundamental optical functions are obtained in the energy range 0–25 eV using experimental reflectivity and characteristic electron loss spectra. The ?₂ and-Im?^?1 spectra are decomposed into components, and their main features are determined. The bands, ?₂, and the localization of transitions in the Brillouin zone are calculated. The experimental and theoretical transitions are compared with theoretical data on the electronic structure of a TlCl crystal.     

Analysis of the high-resolution infrared spectrum of cyclopropane

The high-resolution infrared spectrum of cyclopropane (C₃H₆) has been measured from 100 cm⁻¹ to 2200 cm⁻¹. In that region we have identified 24 absorption bands attributed to six fundamental bands, five combination bands, three hot bands and 10 difference bands. Long pathlength spectra, up to 32 m, facilitated the identification and analysis of many previously unstudied infrared inactive, and Raman and infrared inactive vibrational states, including direct access to two forbidden fundamental states, ν₄ and ν₁₄. An improved set of constants for the ground vibrational state as well as for the fundamental vibrations ν₇, ν₉, ν₁₀, ν₁₁ are also reported. The spectral resolution of the measurements varied from 0.002 cm⁻¹ to 0.004 cm⁻¹.     

对甲氧基苯甲腈的单色共振双光子电离光谱

对甲氧基苯甲腈是一种重要的化学化工原料,本文采用超声分子束技术和共振多光子电离方法获得了对甲氧基苯甲腈的单色共振双光子电离光谱,基态S0到电子激发态S1的0←0跃迁被确定为(35549±2)cm~(-1),结合含时密度泛函理论计算结果对观察到的光谱进行了振动模式标识和描述.实验发现呼吸振动模非常易于激活,其基频和二次泛频光谱很强,三次泛频也可明确标识,观察到大量呼吸振动与其他正则模的结合振动,这是对甲氧基苯甲腈不同于常见的多原子分子的一个重要特性.这些结果为研究对甲氧基苯甲腈的里德堡态、动力学和零动能光谱等提供了重要的参考数据.     

The vapor phase Raman spectra,Raman band contour analyses,Coriolis coupling constants,and e-species force constants of the molecules SPF3, FCCl3, and BrCCl3

The vapor phase Raman spectra of the molecules SPF₃, FCCl₃, and BrCCl₃ have been recorded at pressures of up to 1 atm over the fundamental frequency regions. The Raman band contours of the e-species fundamentals have been analyzed to yield first-order Coriolis coupling constants from which, together with the fundamental frequencies, e-species force constants of the general harmonic potential function have been evaluated. The results for thiophosphoryltrifluoride are compared with those deduced previously on the basis of infrared band contour analyses.     

Raman spectroscopic characterization of the copper,cobalt, and nickel selenites: Synthetic analogs of chalcomenite,cobaltomenite, and ahlfeldite

Raman spectroscopy has been used to study synthetic analogs of the minerals chalcomenite, cobaltomenite, and ahlfeldite occurring in nature. The results obtained are compared with the spectra of these minerals. In general, the majority of vibrational bands of synthetic species are in good agreement with natural chalcomenite, cobaltomenite, and ahlfeldite. The noticeable discrepancies are found for the bands assigned to the deformation mode of selenite groups. A better signal-to-noise ratio realized with synthetic species aids in comprehensive analysis of the spectra, especially in the region of water bands.     

Vibration-rotation intensities for “hot” bands

Vibration-rotation transition moments for “hot” bands are presented assuming the Dunham potential and a power series expansion for the dipole moment function. These results are applied to an analysis of CO intensities where a unique dipole moment function is determined from the experimental slope of the Herman-Wallis factors and the integrated intensities of the fundamental and overtone bands. This is then used together with the theoretical expressions to calculate the “hot” band dipole moment matrix elements which are found to be in good agreement with the experimental results.     

Long-term optical and radio variability analysis of BL Lacertae 2200+420

Based on the radio light curves in 22 GHz and 37 GHz from the Metsahovi monitoring program and the optical light curves in BVRI bands from previously published results and the"Whole Earth Blazar Telescope"(WEBT)archives,we analyze the time delay among 22 GHz,37 GHz and optical bands(B,V,R,I)of BL Lacertae by means of discrete correlation method.The results suggest there exist strong correlation among 22 GHz,37 GHz and optical bands(B,V,R,I)with zero-lag.The 37 GHz lags behind R band by 11 months.The correlation of brightness and color index among BVRI bands,brightness and spectral index between 37GHz and 22 GHz are also investigated.The results show a clear trend of bluer-when-brighter.     

Interferometric determination of the dispersion of vibrational polarizability and the integrated intensities of fundamental bands of 32, 34SF6 and NF3 molecules

The refractivity of gaseous SF₆ and NH₃ in the region of the intense absorption bands of these compounds was measured by two-beam, two-color interferometry using a He-Ne laser and a CO₂ laser tunable throughout its emission lines. Quantitative data on the profiles of the absorption bands of these gases were also obtained by IR Fourier spectroscopy. By using the joint processing of the results of refractometric and spectral measurements on the basis of the Kramers-Krönig formalism, the dispersion dependences of the vibrational polarizabilities of the given molecules were calculated and the integrated intensities of their fundamental vibrational bands were refined. A table of values of total and vibrational polarizabilities at the emission frequencies of the CO₂ laser was compiled.