Showing papers on "Hot band published in 1986"
TL;DR: In this article, the authors reported the observation of Raman scattering associated with the vibrational modes in the diluted magnetic semiconductor (ZnTe) and compared the optical phonons of ZnTe with those of CdTe.
Abstract: We report the observation of Raman scattering associated with the vibrational modes in the diluted magnetic semiconductor ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te. The low-frequency two-phonon density-of-states features in ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te, similar to those of ZnTe, exhibit composition-dependent Raman shifts. Low-frequency disorder-induced one-phonon density-of-states features are also present in the Raman spectra for x\ensuremath{\ge}0.10. The optical phonons of ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te exhibit a variation with x that is intermediate between the two-mode and one-mode situations. The optical modes of ${\mathrm{Zn}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te are compared with those of ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te, the prototype of wide-band-gap diluted magnetic semiconductors. A random-element isodisplacement model is used to describe the behavior of the optical phonons of both alloy systems.
91 citations
TL;DR: In this paper, the vibrational spectrum of SF 6 has been recorded with a Fourier transform i.r. spectrometer at a resolution of 0.05 cm −1 and pressure-path length products of up to 2 × 10 5 Torr-cm.
83 citations
TL;DR: In this article, a vibrational-torsional model was proposed to separate low frequency torsional vibration from higher frequency OH and OO stretching vibrations, and it was shown that the effective trans barrier increases by 75 cm−1 for each quantum of OH stretching excitation but decreases by 50 cm− 1 upon excitation of the OO bond.
Abstract: Laser induced fluorescence detection of the fragments from the unimolecular dissociation of hydrogen peroxide initiated by direct excitation of the fourth overtone of the OH stretching transition (5νOH) is a means of measuring both vibrational overtone predissociation spectra and populations of individual quantum states of the OH products. Because the excitation adds insufficient energy to break the OO bond, the measurements detect reactions of molecules that initially possess substantial thermal vibrational–rotational energy (≥1100 cm−1). The spectroscopic data, in which hot band and high energy transitions are particularly prominent, are fit by a vibrational–torsional model that adiabatically separates the low frequency torsional vibration from the higher frequency OH and OO stretching vibrations. The spectroscopic analysis shows that the effective trans barrier in the torsional potential increases by 75 cm−1 for each quantum of OH stretching excitation but decreases by 50 cm−1 upon excitation of the OO...
83 citations
TL;DR: In this paper, the authors reported the measurement of new high-J transitions (up to J=41) in the fundamental N-H stretch band and of the 1110-0110 bending hot band by velocity modulation infrared laser spectroscopy.
Abstract: We report the measurement of new high‐J transitions (up to J=41) in the fundamental N–H stretch band and of the 1110–0110 bending hot band by velocity modulation infrared laser spectroscopy. These data were combined with measurements of the 100, 0110, and 001 fundamentals of both HNN+ and DNN+, and of the 1110–0110 hot band of DNN+, and of microwave ground state rotational transitions, made by several groups, in a simultaneous weighted least‐squares analysis; from this analysis, the equilibrium structure of protonated nitrogen was determined to be: rNH =1.033 59(43) A, rNN =1.092 766(92) A. Several vibration–rotation and anharmonicity constants were determined; comparisons with high level ab initio calculations are presented.
74 citations
TL;DR: In this article, the vibration-rotation frequency parameters of vibrational states of several isotopic species of N2O were determined from IR spectra obtained with a high-resolution Fourier transform spectrometer.
Abstract: The vibration-rotation frequency parameters of vibrational states of several isotopic species of N2O were determined from IR spectra obtained with a high-resolution Fourier-transform spectrometer. The bands in the 1100 to 1440/cm region were considered. The line frequencies, observed for the lines of the species (N-14)2(O-16), (N-14)(N-15)(O-16), (N-15)(N-14)(O-16), (N-14)2(O-18), (N-14)2(O-17), and (N-15)2(O-16) were analyzed to obtain values of the absolute band centers and upper-state and lower-state rotational constants.
62 citations
TL;DR: In this paper, the observation of a polar bright spot in the atmosphere of Jupiter is characterized by an enhancement in the individual lines of C2H2 which can be interpreted as an enhancement of the acetylene abundance.
50 citations
TL;DR: In this article, the (0,0,5) −(0, 0,0) transition at 15,552 cm−1 in HCN has been measured using a cw laser dye laser, and a White cell with an optical path length of about 0.5 km.
Abstract: The intensity of the (0,0,5)–(0,0,0) transition at 15 552 cm−1 in HCN has been measured using a cw laser dye laser, and a White cell with an optical path length of about 0.5 km. From a photoacoustic spectrum of HCN, the relative band intensity of the (0,0,5)–(0,0,0) transition to the (0,1,5)–(0,1,0) hot band transition has been determined. The integrated band intensity of the (0,0,5)–(0,0,0) band is 2.91(7)×10−23 cm−1/(molecule cm−2) or 17.5(4) cm/mol, which implies a dipole transition moment of 6.70(8)×10−5 D. The (0,1,5)–(0,1,0) band is equal in intensity to the (0,0,5)–(0,0,0) band within experimental error. The self‐broadening and pressure shifts of these bands have also been examined. In the (0,0,5)–(0,0,0) band, the self‐broadening coefficients for both the P and R branch for J between 0 and 19 were measured. For the P branch, the self‐broadening coefficient is 23.7 MHz/Torr for J=1, increases monotonically to a maximum of 48.9 MHz/Torr at J=9, and then decreases monotonically to 21.7 MHz/Torr at J=...
45 citations
TL;DR: The lowest six vibrational hot bands of CF + have been measured in a helium/C 2 F 6 discharge by velocity modulation laser spectroscopy as discussed by the authors, yielding the parameters: ω e = 17926654(18) cm −1 B e = 17204176(75)cm −1, Y 20, = −1322968(54) cm−1, and D 0 = 62086(30)cm−1
40 citations
39 citations
TL;DR: In this paper, Raman excitation profiles (REPs) from a highly excited state in azulene are presented for several vibrational modes, including four fundamentals, a combination, and an overtone, compared to transform theory predictions which are based on the observable absorption spectrum (ABS) of the resonant electronic state.
Abstract: Raman excitation profiles (REPs) from a highly excited state in azulene are presented for several vibrational modes. These include four fundamentals, a combination, and an overtone. Experimental REPs are compared to transform theory predictions which are based on the observable absorption spectrum (ABS) of the resonant electronic state. Though both the REPs and the ABS are multimode in nature, the transform provides a single mode link between the two and allows for extraction of excited state parameters on a mode by mode basis. For several modes, excited state frequencies and Franck–Condon coupling constants are estimated. Observed discrepancies between experiment and transform for other modes raise questions as to the applicability of the ‘‘standard assumptions’’ on which the transform is based to all of the vibrational modes in this electronic state. The strongly enhanced Raman scattering also allows depolarization ratios to be determined for all the azulene symmetric ring vibrations and directly confir...
36 citations
TL;DR: Baggott et al. as discussed by the authors presented FTIR spectra of gas phase cyclobutene and modeled the v=1-3 stretching states of both olefinic and methylenic C-H bonds in terms of a local mode model.
Abstract: In part I of this study [Baggott, Clase, and Mills, Spectrochim. Acta Part A 42, 319 (1986)] we presented FTIR spectra of gas phase cyclobutene and modeled the v=1–3 stretching states of both olefinic and methylenic C–H bonds in terms of a local mode model. In this paper we present some improvements to our original model and make use of recently derived ‘‘x,K relations’’ to find the equivalent normal mode descriptions. The use of both the local mode and normal mode approaches to modeling the vibrational structure is described in some detail. We present evidence for Fermi resonance interactions between the methylenic C–H stretch overtones and ring C–C stretch vibrations, revealed in laser photoacoustic spectra in the v=4–6 region. An approximate model vibrational Hamiltonian is proposed to explain the observed structure and is used to calculate the dynamics of the C–H stretch local mode decay resulting from interaction with lower frequency ring modes. The implications of our experimental and theoretical studies for mode‐selective photochemistry are discussed briefly.
TL;DR: In this article, the molecular structure of CF 3 SiH 3 in the gas phase has been determined by electron diffraction analysis and force constants have been calculated by means of a normal coordinate analysis based on 52 experimental frequencies.
TL;DR: In this paper, the resonance enhanced multiphoton ionization (REMPI) spectra of CH2OH, CH2OD, CD2OH and CD2OD between 420-495 nm are reported.
Abstract: The resonance enhanced multiphoton ionization (REMPI) spectra of CH2OH, CH2OD, CD2OH, and CD2OD between 420–495 nm are reported. Analysis of the excited state vibrational band progressions shows that the spectrum originates from simultaneous two photon absorption to form a 3p Rydberg state (ν00=40 064 cm−1) of the radical. Absorption of a third photon ionized the radical. A normal mode analysis of the REMPI spectra enabled assignments of six active vibrational modes in the excited state. The no isomerization of methoxy radicals into hydroxymethyl radicals was observed. The experimental measurement uncertainty limits this isomerization rate to less than 2.9 s−1 at 300 K.
TL;DR: In this paper, the dynamics of inter- and intramolecular vibrational energy redistribution for CF 2 HCl molecules, multiple-photon excited by means of a CO 2 laser, is studied by a Raman probing technique.
TL;DR: In this paper, the authors reported electronic autoionization studies of N2O using vibrationally resolved constant ionic state (CIS) spectroscopy, and showed that this level of the ion is produced predominantly by photoionization of the target molecules in the (0, 1, 0) level, i.e., via hot band excitation.
Abstract: We report electronic autoionization studies of N2O using vibrationally resolved constant ionic state (CIS) spectroscopy. Vacuum ultraviolet synchrotron radiation is the excitation source, and we determine the relative partial photoionization cross‐section curves for alternative vibrational levels (v’) of the ion by detecting dispersed fluorescence [N2O+(A 2Σ+,v’→X2Π,v‘)] from the ion. Excitation spectra sampling different vibrational levels reveal significant changes in the 3pπ resonance profile, including shifts of the resonance minima, and previously unobserved features. Analysis of the v’=(0,1,0) CIS spectra demonstrate that this level of the ion is produced predominantly by photoionization of the target molecules in the (0,1,0) level, i.e., via hot band excitation. These results are discussed in detail, as well as possible extensions and further studies.
TL;DR: In this article, the v2 = 2 a and v4 = 1 a states were observed by an infrared microwave sideband laser spectrometer with an absolute accuracy of 0.00002 cm−1.
TL;DR: In this paper, the infrared spectrum of the ν 4 band of CH 3 I around 3060 cm −1 was studied at a resolution of 5.4 × 10 −3 cm−1.
TL;DR: In this article, a large number of transitions in the 2 ν 3 and 2 ǫ 3 ← ξ 3 bands of 13 CH 3 F have been recorded at Doppler-limited resolution by means of an infrared laser microwave sideband spectrometer.
TL;DR: In this article, the 2 ν 2 + ν 3 − λ 2 hot band of H 2 18 O has been assigned between 4800 and 6000 cm -1, with an average uncertainty of 8%.
Abstract: 190 lines belonging to the 2 ν 2 + ν 3 − ν 2 hot band of H 2 18 O have been assigned between 4800 and 6000 cm -1 . The intensities of 63 of these were measured with an average uncertainty of 8%. The new results improve the knowledge of water-vapor absorption at 300 K in the specified spectral region.
TL;DR: In this article, spontaneous Raman scattering in a laser intracavity apparatus has been observed by CH3CD3 torsional overtones, and Δv = 2 multiplet transitions up to the sixth level have been measured.
TL;DR: In this paper, single vibronic level fluorescence spectra from the 6112 level in 1B2u benzene and benzene-d6 in a free jet expansion were used to identify high normal mode overtones of the C-C ring breathing mode up to 10,000 cm−1.
Abstract: Single vibronic level fluorescence spectra from the 6112 level in 1B2u benzene and benzene‐d6 in a free jet expansion include sharp transitions to S0 levels identified as high normal mode overtones of the C–C ring breathing mode up to 10 000 cm−1. For these levels, and for the reported method of state preparation, the upper bound for the rate of intramolecular vibrational redistribution is kIVR <1012 s−1. This rate is several times smaller than for C–H or C–D stretch local mode levels of similar energy when they are prepared via overtone absorption from the ground state.
TL;DR: The vibrational modes of CO adsorbed on a Ni(001) metal surface have been obtained using two different cluster models to represent the on-top and bridge-bonding situations.
TL;DR: In this article, the vibrational spectra of hexachloroethane (HCE) were investigated between 10 and 1000 cm−1 in the temperature range from 40 to 360 K. The three phases were characterized with the help of a normal coordinate analysis and a calculation of the crystal dynamics.
Abstract: The vibrational spectra of hexachloroethane (HCE) were investigated between 10 and 1000 cm−1 in the temperature range from 40 to 360 K. The three phases are characterized. The spectra are interpreted with the help of a normal coordinate analysis and a calculation of the crystal dynamics. A mechanism of the phase transition is proposed.
TL;DR: In this article, a simple molecular orbital diagram has been constructed from the frontier orbitals of S2 and Cl and the predicted changes in the bond strengths and bond angles between the ground state and the excited state are consistent with experimental assignments.
Abstract: A total of 37 absorption bands, lying between 3785 and 4805 A, have been observed during the pyrolysis of S2Cl2 at 750 K. These bands have been tentatively assigned to transitions between the X A‘ state of S2Cl to an unidentified electronically excited state with vibrational frequencies ω’1 =480 cm−1 and ω2 =407 cm−1. From this assignment it follows that the ground state vibrational frequencies are ω‘1 =659 cm−1, ω‘2 =600 cm−1, and ω‘3 =336 cm−1. A simple molecular orbital diagram has been constructed from the frontier orbitals of S2 and Cl. The predicted changes in the bond strengths and bond angles between the ground state and the excited state are consistent with experimental assignments.
TL;DR: A continuously tunable single-frequency color-center laser spectrometer has been used to rovibrationally analyze the static gas-phase spectrum of the v 1 (C-H stretching) vibration in HCN---H 35 Cl providing molecular parameters: v 1 = 3309.0286(3) cm −1, B 1 = 2007.37(36) MHz and D j 1 = 3.51(13) × 10 −3 MHz.
TL;DR: Using velocity modulation detection, infrared diode laser absorption spectra of seventeen transitions of the fundamental band of HCl+ have been measured covering both 2 Π 1/2 and 2Π 3/2 states of H 35Cl+ and H 37Cl+.
Abstract: Using velocity modulation detection, infrared diode laser absorption spectra of seventeen transitions of the fundamental band of HCl+ have been measured covering both 2Π1/2 and 2Π3/2 states of H 35Cl+ and H 37Cl+. The transitions were assigned on the basis of their absolute positions and Λ doublet splittings predicted by earlier optical spectra. Some of the additional lines detected, but not yet accurately measured, are tentatively assigned to hot band transitions in HCl+.
TL;DR: In this article, the temperature dependence of the intensities of the Q-branches in the Raman spectrum of gaseous CO2 in the Fermi resonance region was measured in the range from 300 K to 650 K.
Abstract: The temperature dependence of the intensities of the Q-branches in the Raman spectrum of gaseous CO2 in the Fermi resonance region was measured in the range from 300 K to 650 K. The intensity contours were reproduced by computer simulation, taking into account energy levels up to (v1v21v3) = (30°0) as final states. Calibration curves are given for the determination of temperatures from the intensity distribution in the hot bands of the Raman spectrum of CO2.
TL;DR: In this paper, computer assisted analysis of hundreds of double resonance signals from CF 2 Cl 2 has yielded constants for the hot bands ν 6 + ν 4 − ν 5 of CF 2 35 Cl 2 and CF 2 37 Cl 2.
TL;DR: In this article, the resonance Raman (RR) spectra obtained with several excitation wavelengths are compared for the following porphyrin-IX compounds: free-base protoporphrin-IX, meso-porphyrin -IX and haematoporphyrIN-IX and copper-protoporphrin -IX, copper-mesoporphyn-IX dimethyl esters.
Abstract: Resonance Raman (RR) spectra obtained with several excitation wavelengths are compared for the following porphyrin-IX compounds: free-base protoporphyrin-IX, meso-porphyrin-IX and haematoporphyrin-IX and copper-protoporphyrin-IX and copper-mesoporphyrin-IX dimethyl esters. Certain bands in the RR spectra of all the free-base porphyrins or copper complexes are unaffected with respect to frequency, whereas there is a shift in the frequencies of some vibrational modes in some systems. From a comparative study of the systems which have identical geometrical arrangements, no extra features were found in the RR spectra of protoporphyrin which can be attributed directly to the vinyl group modes. This suggests that the vibrational modes of vinyl groups do not distort the excited electronic state substantially, and are not effective in vibronic coupling with the electronic states of the porphyrin macrocycle and therefore do not gain intensity under resonance excitation. Most of the vibrational modes are strongly coupled and there are no extra distinct features in the RR spectra of PP which may be associated with selective vibrational coupling of the vinyl group modes with the porphyrin skeletal modes.