Raman Overtone Research Articles

Raman OD-Stretching Overtone Spectra from Liquid D2O between 22 and 152 °C

Raman OD-stretching (first) overtone spectra, X(Z,X+Z)Y, X(ZZ)Y, and X(ZX)Y, from pure D2O between 22 and 98 °C yield an isosbestic frequency near 5130 cm-1. This value corresponds to the X(ZX)Y fundamental isosbestic observed near 2624 cm-1, but not to the X(ZZ)Y fundamental isosbestic near 2429 cm-1, because the fundamental 2375 cm-1 correlated deuteron OD stretch, ν1, and its overtone, 2ν1, are weak in the X(ZX)Y spectra, compared to the three higher-frequency fundamentals, ν2, ν3, and ν4, and their overtones. The 2375 and 2475 cm-1 fundamentals and their overtones probably engage in coupling with a ≈175 cm-1 LA phonon which is supported by H-bonded aggregates or patches, whereas the corresponding data for H2O provide clear and unequivocal evidence for this LA coupling. Deconvolution of the X(Z,X+Z)Y overtone spectra, 22−152 °C, plus van't Hoff treatment yields an enthalpy for H bond, O−D···O, rupture of 2.8 ± 0.2 kcal/mol O−D···O, in good agreement with present values of 2.6 ± 0.2 and 2.8 ± 0.2 kcal/mol O−D···O, obtained from the fundamental X(ZZ)Y and X(ZX)Y spectra. Raman overtone measurements are important because the spacing between the four-Gaussian components is large in the overtone OD- and OH-stretching contours compared to the fundamentals.

Ultrafast dynamics of the В state of I2 in condensed rare gases

The resonance Raman overtone progressions of I2 in liquid Xe following excitation of the В state are discussed and compared with similar data in solid Ar. It is shown that the Raman contribution from the В state is damped by predissociation within one recurrence and the Raman emission can be treated as that of an outgoing wave packet crossing over to purely repulsive B", a and a' states. The curve crossing can be localised in space and time from the Raman data. Predissociation to B" is important, especially for excitation near the bottom of the well. A Golden-Rule type of expression describes the data poorly and a Landau-Zener approach is used. The coupling is induced by the solvent and similarities between liquid Xe and solid Ar indicate that structural details of the surroundings are of minor importance since the transition occurs already during the first elongation. A broad emission background from resonance and vibrationally hot fluorescence is also observed. It is attributed to incoherent returns of the predissociated wave packets in the В state Franck-Condon region and to vibrational cooling.

P-R doublet enhanced CARS lines of NaH

We have observed an enhancement of the P and R lines from X 1 Σ +− A 1 Σ + transitions in the NaH molecules through coherent anti-Stokes Raman scattering (CARS). The NaH molecules were photochemically produced in a sodium-hydrogen gas mixture. By changing the pump laser frequency ω pump the location of these P-R enhanced doublet CARS lines shift by the amount of detuning in the usual ω pump-ω stokes representation. However, in the 2ω p-ω s representation these P and R lines remain stationary. Double electronic resonances and upper state Raman overtone CARS lines have been observed. For P 5(9,0) and R 5(9,0) enhanced CARS lines we tuned the pump laser over the electronic resonance in order to obtain the resonance excitation curve for the double electronic resonance. This excitation curve exhibits a characteristics central dip.

Calculated Raman overtone intensities for H2 and D2

Dynamic dipole polarizabilities pertinent to the Raman intensities of the fundamental and first two overtones of H2 and D2 have been calculated. To do this an energy-shifted sum-over-states formula has been used in conjunction with accurate electron-correlated wave functions. The results for the relevant polarizability ratios agree, in the static limit, with a previous calculation. The dynamic values are in fair agreement with the recent experimental ones for H2 but there is a strong disagreement with a previous experimental determination for D2.

Raman overtone intensities measured for H2

The Raman spectra of the vibrational fundamental, first overtone and second overtone transitions of the H2 molecule were recorded using visible and ultraviolet argon–ion laser excitation. The ratios of transition polarizability matrix elements, α01,21/α01,11 and α01,31/α01,11, were determined from the measured intensities of the Q(1) Raman lines v,J=0,1→v′,1 for v′=1,2,3. The experimentally determined value of the Raman first overtone matrix element is in good agreement with the value from the best ab initio calculation.

Torsional motion of the CH 3 groups of propane studied by Raman overtone spectroscopy

The Raman spectrum of propane is recorded between 300 and 900 cm −1; first and third overtones are observed with an Ar + laser intracavity setup. This spectrum is analyzed by means of a model with two hindered and coupled methyl rotors. Since the levels probed extend to the region above the torsional barrier ( V 3=1353 cm −1), all the relevant molecular parameters, in particular the coupling between the methyl rotors, could be accurately determined. By means of a classical approach we have obtained further insight into the qualitative structure of the torsional spectrum.

Resonance Raman spectra oftrans-1,3,5-hexatriene in solution: Evidence for solvent effects on excited-state torsional motion

Resonance Raman spectra of trans-1,3,5-hexatriene in cyclohexane, hexane, methanol, and perfluorohexane are compared with the corresponding vapor phase spectra. The absolute cross sections in cyclohexane indicate that the solvation induced electronic spectral breadth is partly homogeneous (amplitude level in the Raman process) and partly inhomogeneous. Overtones and combination bands involving torsional modes, particularly the central double bond torsion, are dramatically reduced in intensity upon solvation, the reduction being greatest in solvents that generate the largest red shift of the absorption. Quantitative modeling of the cyclohexane data shows that these intensity changes can be attributed only in part to the preferential damping of low-frequency overtones induced by the increase in electronic homogeneous linewidth upon solvation. The remaining intensity reduction may arise either from a stiffer excited-state potential surface for double bond twisting in solution or from coordinate-dependent dephasing in the upper electronic state. Additionally, time-dependent wave packet propagation techniques are employed to estimate the barrier to double bond twisting in the excited state from the experimental ratio of four-quantum to two-quantum Raman overtone intensities.

Radiative processes in air excited by an ArF laser

The emission spectrum of air that is excited by an ArF laser has been investigated experimentally and theoretically to determine the conditions under which fluorescence from O2 can be used for the measurement of temperature in aerodynamic flows. In addition to the expected fluorescence from O2, the spectrum from excitation with an intense laser beam is shown to contain significant contributions from the near-resonant Raman fundamental and overtone bands, the four-photon fluorescence excitation of C produced from ambient CO2, and possibly the three-photon excitation of O2+. The nature of the radiative interactions contributing to these additional features is described.

ChemInform Abstract: Calculation of the Electronic Spectra of Conjugated Cyclic PNS Ring Systems (I) and (II) from Preresonance Raman Fundamental and Overtone Intensities.

Chemischer InformationsdienstVolume 17, Issue 11 Physical Organic Chemistry ChemInform Abstract: Calculation of the Electronic Spectra of Conjugated Cyclic PNS Ring Systems (I) and (II) from Preresonance Raman Fundamental and Overtone Intensities. Y.-Y. YANG, Y.-Y. YANGSearch for more papers by this authorJ. I. ZINK, J. I. ZINKSearch for more papers by this author Y.-Y. YANG, Y.-Y. YANGSearch for more papers by this authorJ. I. ZINK, J. I. ZINKSearch for more papers by this author First published: March 18, 1986 https://doi.org/10.1002/chin.198611041AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume17, Issue11March 18, 1986 RelatedInformation

Resonance Raman overtone intensity calculations of a matrix-isolated I2 molecule by the symmetrized split operator fast Fourier transform method

Resonance Raman overtone progressions of I2 in an Ar crystal are computed using the time dependent formula of Raman scattering which has been known to possess distinct computational advantages over the Kramers–Heisenberg–Dirac sum-over-states method, especially when treating condensed phase systems. The symmetrized split operator fast Fourier transform method, which provides a simple and accurate algorithm, is applied to computing the time evolution of the vibrational wave packet involved in the time dependent formula. Our calculated result based on Heller’s time dependent formula is in qualitative agreement with the experimental one of Grzybowski and Andrews, but there are some discrepancies between them (for example, the overtone enhancement with the 530.9 nm excitation is not so strong as the experimental one). Those discrepancies are ascribed to the adopted assumption that the line shape for a vibronic transition is a Lorentzian and it is independent of the vibrational level in the excited electronic state. The use of an incident frequency dependent line shape proves to resolve the disagreements to a great extent, which implies that to obtain perfect agreement one needs to explicitly deal with the motion of the trapped molecule and its neighboring host atoms.

Calculation of the electronic spectra of conjugated cyclic PNS ring systems from preresonance Raman fundamental and overtone intensities

Calculation of the electronic spectra of conjugated cyclic PNS ring systems from preresonance Raman fundamental and overtone intensities

Raman overtone spectroscopy of ethylene

For ethylene (C 2H 4) overtone Raman Q-branches have been measured between 800 and 6300 cm −1. The observed bands amongst which transitions as weak as 10 −4 times the Raman ν 1 intensity are assigned. Anharmonic resonances manifest themselves in enhanced Raman scattering intensities at band origins neighbouring a strong transition, e.g. for 2ν 10, ν 2 and ν 3 and for 2ν 12, ν 1, 2ν 2 and ν 2 + 2ν 10. For the out-of-plane modes 2ν 3, 2ν 7 and 2ν 4 this resonance has been found to be much weaker or even absent. Even five triple and one quadruple combination band could be assigned. The band origin of ν 4 + ν 7 = 1964 ± 2 cm −1 (species B 1g) has been obtained from the Δ K = 2 transitions.

Temperature dependence of the Raman OH-stretching overtone from liquid water

The first Raman overtone of the OH-stretching vibration from highly purified liquid water has been examined quantitatively in the temperature range of 20–95 °C, and at frequencies from about 5500–8000 cm−1. The overtone Raman spectra show contour shapes, depolarization ratio dispersion, and an isosbestic frequency (6960±25 cm−1, uncorrected; 6900±25 cm−1, density and refractive index corrected) which, apart from the effects of anharmonicity, tend to mimic the fundamental, including its major four-component substructure. The two components at about 7030 and 6850 cm−1 were interpreted, respectively, in terms of nonhydrogen-bonded OH, and triply hydrogen-bonded OH groups, which are common to the three-bonded H2O species, whereas two components at about 6665 and 6160 cm−1 were interpreted as intermolecular coupling components of the fully hydrogen-bonded, i.e., four-bonded H2O species. A ΔH° value of −2.5 Kcal/mol hydrogen bond was obtained from the temperature dependence of ratios of the combined component intensities of these two pairs, in agreement with results from previous Raman fundamental measurements. The feature near 6160 cm−1 was found to be better resolved in the spectrum than its fundamental analog, indicating that anharmonicity is advantageous in elucidating contour substructure.

ChemInform Abstract: EXCITED STATE DISTORTIONS FROM RESONANCE RAMAN OVERTONE INTENSITIES IN TRIPOTASSIUM NITROSYLPENTACYANOCHROMATE (K3(CR(CN)5NO))

Chemischer InformationsdienstVolume 15, Issue 24 Physical Organic Chemistry ChemInform Abstract: EXCITED STATE DISTORTIONS FROM RESONANCE RAMAN OVERTONE INTENSITIES IN TRIPOTASSIUM NITROSYLPENTACYANOCHROMATE (K3(CR(CN)5NO)) Y.-Y. YANG, Y.-Y. YANGSearch for more papers by this authorJ. I. ZINK, J. I. ZINKSearch for more papers by this author Y.-Y. YANG, Y.-Y. YANGSearch for more papers by this authorJ. I. ZINK, J. I. ZINKSearch for more papers by this author First published: June 12, 1984 https://doi.org/10.1002/chin.198424043AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume15, Issue24June 12, 1984 RelatedInformation

Ab initio study of rotational isomerism in 1,3-butadiene. Effect 21 of geometry optimization and basis set size on the barriers to rotation and on the stable rotamers

Analytic gradient (force) methods at the STO-3G, 3-21G, 6-31G and 6-31G* basis set levels have been used to optimize the geometry of 1,3-butadiene at each critical point (minima, maxima) in the torsional potential energy curves for rotation about the central CC bond (dihedral angle θ). Each CHCH 2 group was constrained planar and the effect of this geometry constraint was investigated by additional STO-3G and 3-21G optimizations. The planar trans conformation (θ = 180°) is predicted to be most stable, in agreement with experiment. Small variations in the predicted relative energy (Δ E) and in the position of the transition state (TS) for rotation from the trans position are observed: Δ E = 23.5, 23.6, 25.9 and 25.4 kJ mol −1 and θ = 95.0, 101.8, 101.6 and 101.5° for the STO-3G, 3-21G, 6-31G and 6-31G* basis set optimizations, respectively. The STO-3G optimizations predict an energy minimum for the planar cis conformation (θ = 0°), 7.7 kJ mol −1 above the trans minimum. All three larger basis sets predict a maximum for the cis structure, with small gauche—gauche rotational barriers (2.0–4.1 kJ mol −1, the largest value corresponding to optimizations with the 3-21G basis set and non-planar CHCH 2 groups). The gauche minimum is predicted to lie 11.3–13.2 kJ mol −1 above the trans, at θ's in the range 35.5–38.5°. The positions and relative energies of the critical points in the torsional potential energy curves predicted by the 3-21G, 6-31G and 6-31G* optimizations are in good agreement with those proposed by Durig, et al. [1] to reproduce the Raman overtone spectrum of 1,3-butadiene for a gauche—trans rotamer equilibrium. A series of 6-31G** computations with the optimized geometries from the smaller basis sets indicates that optimization at the 6-31G** basis level would give results similar to those obtained with the above three split-valence basis sets.

ChemInform Abstract: REGULARITIES IN THE RESONANCE RAMAN OVERTONE SPECTRUM FROM THE THIRD EXCITED STATE OF CHRYSENE

Chemischer InformationsdienstVolume 14, Issue 17 Physical Organic Chemistry ChemInform Abstract: REGULARITIES IN THE RESONANCE RAMAN OVERTONE SPECTRUM FROM THE THIRD EXCITED STATE OF CHRYSENE W. L. PETICOLAS, W. L. PETICOLASSearch for more papers by this authorL. CHINSKY, L. CHINSKYSearch for more papers by this authorP.-Y. TURPIN, P.-Y. TURPINSearch for more papers by this authorA. LAIGLE, A. LAIGLESearch for more papers by this author W. L. PETICOLAS, W. L. PETICOLASSearch for more papers by this authorL. CHINSKY, L. CHINSKYSearch for more papers by this authorP.-Y. TURPIN, P.-Y. TURPINSearch for more papers by this authorA. LAIGLE, A. LAIGLESearch for more papers by this author First published: April 26, 1983 https://doi.org/10.1002/chin.198317045AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue17April 26, 1983 RelatedInformation

Regularities in the resonance Raman overtone spectrum from the third excited state of chrysene

The frequency doubled 514 nm line of the argon laser at 257 nm is shown to fall exactly in the 0–1 absorption band of the third electronic absorption band of chrysene. Resonant Raman scattering from this vibronic state shows three strong Raman bands in the fundamental region (900–1700 cm−1) as well as bands in the overtone and combination region (2500–5000 cm−1). Only the fundamental at 1384 cm−1 shows overtone bands and it also shows combination bands with the other two. The intensity of all of the Raman bands as well as the absorption spectrum is calculated from vibronic theory on the assumption that one band (1384 cm−1) is greatly displaced in the excited state and the large Franck–Condon factors from this band helps to enhance the intensity of the other two bands which are only slightly displaced. Since the third electronic state wave function has a single node which divides the long axis of the molecule, it is suggested that the 1384 cm −1 vibration also has a single node and thus the vibration is a longitudinal stretching of the chrysene molecule.

Excited state geometry of uracil from the resonant Raman overtone spectrum using a Kramers–Kronig technique

The Kramers–Kronig transform technique of Blazej and Peticolas is extended to permit the calculation of overtone and combination bands in a resonant Raman spectrum relative to the fundamentals. The method is applied to the ultraviolet (257 nm) resonant Raman spectrum of uracil which exhibits five fundamental bands and numerous overtone and combination bands. The method permits the determination of Δej the shift of the excited state potential energy minimum along the jth normal mode for each of the five resonant Raman active modes. The Δej values obtained are in reasonable agreement with those obtained earlier from the absorption spectrum and excitation profiles of the fundamentals. However, no internal standard for the experimental determination of Raman intensities is required nor is it necessary to assume any value for Γ the vibronic linewidth. The shape of the absorption band and relative intensities of the harmonics to the fundamental are sufficient to obtain the value of each Δej.

Theory of resonant Raman scattering. II. Overtones and hot bands

Resonant Raman scattering is discussed in the framework of the Green’s function method in both the strong and weak vibronic coupling limits. We further elaborate on the meaning of each matrix element of the Green’s function, evaluated in the convenient basis set which is commonly referred to as the Longuet–Higgins representation. Cross sections for absorption, Rayleigh, Raman fundamentals, Raman overtones, hot bands, etc., can all be related to the matrix elements of the Green’s function. It is further emphasized that only in the vibronic view elaborated here does a simple and direct correlation exist between the light scattering processes and the Green’s functions. Some typical excitation profiles for overtones and hot bands are calculated and the consequences of strong vibronic couplings are discussed in contrast to the weak vibronic coupling case.

Raman spectral studies on vibrational relaxation functions using overtone bands

Comparison of the half-widths of Raman isotropic fundamental and overtone bands for some simple polar molecules shows that current theories of vibrational relaxation do not properly predict the observed broadening on going from n = 1 ← 0 to n = 2 ← 0.