Absorption in Ultra-Peripheral Nucleus-Atom Collisions in Crystal

The Glauber theory description of particle- and nucleus-crystal Coulomb interactions at high-energy is developed. The allowance for the lattice thermal vibrations is shown to produce strong absorption effect which is of prime importance for quantitative understanding of the coherent Coulomb excitation of ultra-relativistic particles and nuclei passing through the crystal.Comment: 8 pages, LaTe

The Si-H Stretching Fundamentals of H328SiD

The ν1(A1) and ν4(E) Si-H stretching fundamentals of H3SiD have been recorded at an effective resolution of 0.006 cm-1 between 2050 and 2300 cm-1. A total of about 2500 rovibrational transitions of the H328SiD isotopomer have been assigned with J′ up to 27 and K′ up to 22. A large number of "perturbation allowed" Δk = ±3 transitions have been identified in both the ν1 and ν4 bands. The assigned transitions have been analyzed using two different theoretical models, which took into account several rovibrational interactions between and within the ν1 = 1 and ν4 = 1 states, yielding a standard deviation of each fit of ca. 0.0004 cm-1, which may be compared with the experimental precision (ca. 0.0001 cm-1). Improved ground state parameters have also been obtained by means of ground state combination differences. © 1997 Academic Press

The \u3bd 2\u2009+\u2009\u3bd 4 and 2\u3bd 2\u2009+\u2009\u3bd 5 high-resolution infrared bands of FClO3

The high-resolution infrared spectra of the mono isotopic species (FClO3)-Cl-35-O-16, (FClO3)-Cl-37-O-16, (FClO3)-Cl-35-O-18 and (FClO3)-Cl-37-O-18 have been analysed in the region of the nu(2) + nu(4) and 2 nu(2) + nu(5) perpendicular combination bands, from 1920 to 2060 cm(-1). Both bands are perturbed by the anharmonic interaction effective between the nu(2) = nu(4) = 1 and nu(2) = 2, nu(5) = 1 excited states of E symmetry. The nu(2) + nu(4) bands are of medium-strong intensity, while the 2 nu(2) + nu(5) bands are very weak. Since the origins of the two bands differ by about 10 cm(-1), the 2 nu(2) + nu(5) bands at lower wavenumbers are almost completely hidden by nu(2) + nu(4). In total, about 3400, 2400, 2800 and 3200 transitions have been assigned for (FClO3)-Cl-35-O-16, (FClO3)-Cl-37-O-16, (FClO3)-Cl-35-O-18 and (FClO3)-Cl-37-O-18, respectively. The assignments of each dyad have been analysed simultaneously with the inclusion of the anharmonic resonance term in the model Hamiltonian. The ro-vibration parameters of the nu(2) = nu(4) = 1 and nu(2) = 2, nu(5) = 1 excited states have been obtained, together with the deperturbed band origins and the anharmonic resonance coefficients W-245. Combining the nu(2) + nu(4) origins with those of the nu(2) and nu(4) fundamentals, the anharmonicity constants x(24) have been derived for the four molecules and compared with the ab initio values calculated taking into account the Fermi resonance

DOPPLER SPECTROSCOPY OF HOCl IN THE 7000cm−17000 cm^{-1} REGION

[1] K. Hedberg and R.M. Badger, J. Chem. Phys. 19 508-509 (1951).Author Institution: Dipartimento di Chimica-Fisica e Inorganica, Viale Risorgimento; Instituto de Estructura de la Materia, C.S.I.C.The spectrum of HOCl in the $6700-7230 cm^{-1}$ region has been recorded at $0.01 cm^{-1}$ resolution (Doppler limits $0.013 cm^{-1}$) on a Bomem DA3.002 Fourier Transform spectrometer. The sample was prepared by admitting $Cl_{2}$ gas into an evacuated flask containing a slime of red mercury oxide and water scattered on the walls. The total pressure was 20 Torr and the pathlength through the multiple reflection cell was 6 m. The $2\nu_{1}$ band ($7038.7 cm^{-1}$) had been observed before [1] at low resolution, and a complete analysis has been carried out for the first time. Work on other overtone and combination bands is on the way

High resolution infrared study of SbHD2: The ground state and the Sb-H stretching bands nu1 and 2nu1

High resolution infrared spectra of (SbHD2)-Sb-121 and (SbHD2)-Sb-123 have been studied in the region of nu(1), the Sb-H stretching fundamental, from 1780 to 1990 cm(-1). The 2 nu(1) stretching overtone band of (SbHD2)-Sb-123, located in the 3640-3790 cm(-1) range, has also been investigated. The SbHD2 molecule is an asymmetric rotor of C-s symmetry with the asymmetry parameter kappa = 0.61. The nu(1) band is of hybrid type, formed by strong C-type and weak B-type transitions, and almost unperturbed. For (SbHD2)-Sb-123, 2092 transitions have been assigned: 70% of these belong to the C component, the other 30% are of B-type. The assigned transitions have been fitted using a Watson type S-reduced Hamiltonian in the lilt representation, with a standard deviation of the fit sigma = 0.45 x 10(-3) cm(-1). In order to determine the ground state parameters all possible ground state combination differences (GSCD) have been generated from the v, transitions. In total, 3942 GSCD up to J '' = 27, K ''(a) = 25, and K ''(c) = 20 have been fitted with sigma = 0.52 x 10(-3) cm(-1). Only C-type transitions have been observed in the weak 2 nu(1) overtone band. The 556 assigned transitions have been fitted with sigma = 2.6 x 10(-3) cm(-1) using the same Hamiltonian as for nu(1). In the nu(1) band of (SbHD2)-Sb-121 771 C-type transitions have been assigned, and the nu(1) = 1 spectroscopic constants obtained from a fit with sigma = 0.70 x 10(-3) cm(-1). Using 618 GSCD the ground state spectroscopic constants of (SbHD2)-Sb-121 have been derived with a = 1.0 x 10(-3) cm(-1). The molecular parameters for the ground and the nu(1) = 1 states of the two isotopologues agree well. The quartic theoretical ab initio force field of SbH3 has been used to predict all relevant spectroscopic parameters for (SbHD2)-Sb-123, (SbHD2)-Sb-121, (SbHD2)-Sb-123, and (SbH2D)-Sb-121. Relations between the harmonic frequencies and between the anharmonicity constants obtained in the expanded local mode theory, for the XH3 -> XH2D/XHD2 isotopic substitution, have been compared with those obtained in the present study. (C) 2010 Elsevier Inc. All rights reserved

High resolution infrared and Raman spectroscopy of \u3bd2 and associated combination and hot bands of 13C12CD2

Infrared and Raman spectra of dideuterated acetylene containing one 13C atom, 13C12CD2, have been recorded and analysed to obtain detailed information on the fundamental 2 band and associated combination and hot bands. Infrared spectra were recorded at 4103cm1 resolution in the region 11502900cm1, which contains combination and hot bands from the ground and the bending v4\ubc1 and v5\ubc1 states. The Q-branches of the 2 fundamental and associated hot bands (2\ufe44, 2\ufe55, 2\ufe2424, 2\ufe2525 and 2\ufe4\ufe5(4\ufe5)) were recorded using inverse Raman spectroscopy, with an instrumental resolution of about 3103cm1. In addition, the observation of the 222 Raman band was carried out populating the v2\ubc1 state by stimulated Raman pumping. In total, 11 Raman and 9 infrared bands were analysed, involving all the l-vibrational components of the excited stretchingbending manifolds up to vt\ubcv4\ufev5\ubc2. A simultaneous analysis of all infrared and Raman assigned transitions has been performed on the basis of a theoretical model which takes into account the rotation and vibration l-type resonances within each vibrational manifold and the DarlingDennison anharmonic resonance between the 2\ufe24 and 2\ufe25 states. The parameters obtained reproduce the assigned transition wavenumbers with a standard deviation of the same order of magnitude as the experimental uncertainty

Infrared Spectroscopy of HOCl in the 4000-10 000 cm-1 Region

The vibration-rotation spectra of both 35Cl and 37Cl isotopomers of HOCl have been recorded in selected regions between 3900 and 10 500 cm-1 More than 6000 transitions were assigned to the following overtone and combination bands: ν1 + ν3, ν1 + ν2, ν1 + 2ν2, and 3ν1. A Watson-type Hamiltonian in the S reduction and Ir representation was adopted for the analysis, and the vibration-rotation parameters were derived for the excited states. Their values, together with spectroscopic parameters of the fundamental bands reported in the literature, allowed the calculation of a large set of anharmonicity constants and the vibrational dependence of the rotational constants. © 1994 Academic Press. All rights reserved.Peer Reviewe

Communication: Observation of homonuclear propensity in collisional relaxation of the 13C12CD2 (v2 = 1) isotopologue of acetylene by stimulated Raman spectroscopy

We report the first experimental observation of homonuclear propensity in collisional relaxation of a polyatomic molecule. A pump-probe stimulated Raman setup is used to pump population to a single rotational level of the v2 = 1 vibrationally excited state in 13C12CD2 and then monitor the redistribution of the rotational population that has taken place after a fixed delay. The Q-branch of the 2\u3bd2\u2013\u3bd2 band shows a pattern of intensity alternation between the even and the odd rotational components, with the greater intensities always corresponding to the rotational levels with the same parity as the one where all the population was initially deposited. The effect can be explained by the existence of a propensity rule that favors collisional relaxation between rovibrational levels of the same parity