High resolution rotation–vibration Raman spectra of acetylene. I. The spectrum of C2H2

1980 ◽  
Vol 58 (4) ◽  
pp. 534-543 ◽  
Author(s):  
E. Kostyk ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
High Resolution ◽  
Raman Spectra ◽  
Gas Pressure ◽  
Multiple Reflection ◽  
Slit Width ◽  
Lower State ◽  
Vibrational States ◽  
Band Origin ◽  
Raman Cell

The Raman spectrum of gaseous acetylene was excited in a multiple-reflection Raman cell by a single-moded Ar+ laser and recorded photographically; the gas pressure was 380 Torr and the spectral slit-width ~0.1 cm−1. The three Raman-active fundamentals ν1, ν2, and ν41 of C2H2 were analyzed to give the band origin, ν0, and the upper state constants, B1 and D1; accurate infrared values of the lower state constants, B0 and D0, were assumed in the analysis. The values of the constants for the ν2 band illustrate the accuracy obtained: ν0 = 1974.317(2), B1 = 1.170419(14), D1 = 1.579(18) × 10−6 cm−1. Five difference bands originating in transitions from the low-lying ν4 = 1 and ν5 = 1 vibrational states were also measured and analyzed.

High resolution rotation–vibration Raman spectra of benzene. I. The totally symmetric bands of C6H6

1978 ◽  
Vol 56 (7) ◽  
pp. 974-982 ◽  
Author(s):  
A. B. Hollinger ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
High Resolution ◽  
Least Squares ◽  
Raman Spectra ◽  
Multiple Reflection ◽  
Slit Width ◽  
Linear Least Squares ◽  
Raman Cell ◽  
Least Squares Minimization

The Raman spectrum of benzene vapour was excited in a multiple reflection Raman cell by an Ar+ laser and was photographed with a spectral slit width of ~0.17 cm−1. All seven Raman-active fundamentals were observed. Analyses of the totally symmetric ν1 and ν2 bands are given in this article. About 150 maxima were observed for ν2 (C—C stretching) and ~100 for ν1 (C—H stretching); the latter was to some extent obscured by the ν15 band. These partially resolved rotational structures were analyzed by setting up suitable schemes of approximate assignments for the maxima and calculating the band constants by a linear least-squares minimization.

High resolution rotation–vibration Raman spectra of benzene. II. The doubly degenerate bands of C6H6

1978 ◽  
Vol 56 (11) ◽  
pp. 1513-1525 ◽  
Author(s):  
A. B. Hollinger ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
High Resolution ◽  
Computer Program ◽  
Raman Spectra ◽  
Multiple Reflection ◽  
Slit Width ◽  
Molecular Constants ◽  
Raman Cell

The Raman spectrum of benzene vapour was excited in a multiple reflection Raman cell by an Ar+ laser and was photographed with a spectral slit width of ~ 0.15 cm−1. The results for the five doubly degenerate Raman-active fundamentals are given in this communication. More than 150 maxima were resolved in the ν17 band and the spectrum was analyzed with a computer program to give ν17 = 1177.776(10) cm−1, B1 – B0 = 1.00(4) × 10−4, C1 – C0 = −0.50(2) × 10−4 cm−1, and ζ17 = 0.010(1). About 60 maxima were recorded in the ν18 band; molecular constants were determined but with less precision than for ν17. The ν15 band (partially overlapped by ν1) and the (ν16, ν2 + ν18) Fermi diad showed resolved structure but no detailed analyses were possible. The ν11 band showed no resolved structure.

High resolution rotation–vibration Raman spectra of acetylene. II. The spectra of C2D2 and C2HD

1980 ◽  
Vol 58 (6) ◽  
pp. 912-920 ◽  
Author(s):  
E. Kostyk ◽  
H. L. Welsh
Keyword(s):  
High Resolution ◽  
Raman Spectra ◽  
Ground State ◽  
Multiple Reflection ◽  
Acetylene Molecule ◽  
Band Origin ◽  
Infrared Studies ◽  
Internuclear Distances ◽  
Raman Cell ◽  
Gas Pressures

The Raman spectra of gaseous C2D2 and C2HD were excited in a multiple-reflection Raman cell by a single-moded Ar+ laser and recorded photographically; the gas pressures were in the range, 130–200 Torr, and the spectral slit width was ~ 0.1 cm−1. The ν1, ν2, and ν41 bands of C2D2 and the ν1 and ν2 bands of C2HD were recorded. These were analyzed to give the band origin, ν0, and the upper state constants, B1 and D1; accurate infrared values of the ground state constants, B0 and D0, were assumed in the analyses. Values of the rotation–vibration interaction constants, αi, assembled from Raman and infrared studies of C2H2, C2D2, and C2HD, were used to calculate the equilibrium internuclear distances for the acetylene molecule: re(C—H) = 1.06250 ± 0.00010 and re(C≡C) = 1.20241 ± 0.00009 Å.

High resolution rotation–vibration Raman spectra of benzene. III. The spectrum of C6D6

1979 ◽  
Vol 57 (5) ◽  
pp. 767-774 ◽  
Author(s):  
A. B. Hollinger ◽  
H. L. Welsh ◽  
K. S. Jammu
Keyword(s):  
Raman Spectrum ◽  
High Resolution ◽  
Least Squares ◽  
Raman Spectra ◽  
Multiple Reflection ◽  
Slit Width ◽  
Molecular Constants ◽  
Least Squares Fit

The Raman spectrum of benzene-d6 vapour was excited in a multiple reflection cell by an Ar+ laser and was photographed with a spectral slit width of ~0.15 cm−1. Extensive structure (164 maxima) was observed for the ν2 (C—C stretching) fundamental but only the S branch (39 maxima) of the ν1 (C—D stretching) band was well-resolved. These totally symmetric bands were analysed and molecular constants determined from a least-squares fit. Three doubly degenerate bands were observed; ν15 and ν16 were unresolved, and in ν17 only 19 lines could be measured. Consequently, no detailed analyses were possible but the values of some molecular constants were estimated.

High-resolution Fourier transform study of the ν11 and ν7 fundamentals of cyclopropane

1984 ◽  
Vol 62 (12) ◽  
pp. 1369-1373 ◽  
Author(s):  
Josef Pliva ◽  
J. W. C. Johns
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Spectroscopic Constants ◽  
Hamiltonian Matrix ◽  
Matrix Elements ◽  
Vibrational States ◽  
Coriolis Interaction ◽  
Band Origin ◽  
The Matrix ◽  
Parallel Band

The absorption spectrum of cyclopropane, C3H6, was measured in the region between 790 and 950 cm−1 on a high-resolution Fourier transform spectrometer. The section containing the Q-branches of the perpendicular band of the ν11 vibration of species E′ was deconvolved to an effective line width of 0.0020–0.0025 cm−1. The structure of the ν11 band is strongly affected by l-type resonance. A total of 88 sub-bands with KΔK = −42 to 45 have been assigned in this band. The K = 4–3 and 2–3 sub-bands both exhibit K doubling of the lines with high J resulting from a combined effect of the off-diagonal matrix elements [Formula: see text], [Formula: see text], and [Formula: see text] with the l doubling in the K = 1, l = 1 state. Otherwise, the ν11 band is found to be free of perturbations by other vibrational states, in spite of the fact that a Jx,y Coriolis interaction is allowed by selection rules with the ν7 band (species [Formula: see text]) whose band origin is only 14.38 cm−1 below that of ν11. This shows that the value of [Formula: see text] is essentially zero. Also, the allowed Jz Coriolis interaction with the ν10 state, which lies 160.01 cm−1 above ν11, does not noticeably affect the two bands. A Hamiltonian matrix, including the matrix elements responsible for the K doubling and l-type resonance, was used for the treatment of the ν11 band. A set of accurate ground state constants and spectroscopic constants for the upper state ν11 is reported that reproduces 3240 observed lines of this band with a standard deviation of 0.0009 cm−1. Lines of the parallel band ν7 are just barely seen between the ν11 lines, which are perhaps 30–50 times stronger. Spectroscopic constants for the ν7 band have been obtained from 135 individual lines assigned to the Q- and R-branches of sub-bands with K = 6–21.

THE RAMAN SPECTRA OF LIQUID AND SOLID H2, D2, AND HD AT HIGH RESOLUTION

1962 ◽  
Vol 40 (1) ◽  
pp. 9-23 ◽  
Author(s):  
S. S. Bhatnagar ◽  
Elizabeth J. Allin ◽  
H. L. Welsh
Keyword(s):  
Raman Spectrum ◽  
High Resolution ◽  
Raman Spectra ◽  
Vibrational Frequencies ◽  
Dispersion Forces ◽  
Present Communication ◽  
Linear Dispersion ◽  
Vibrational Coupling

The Raman spectra of liquid (~18° K) and solid (~2° K) n-H2, p-H2, n-D2, o-D2(80%), and HD were photographed with a reciprocal linear dispersion of 3 to 6 cm−1 per mm. The S0 rotational lines show broadening of a few cm−1 but the Q1 vibrational lines are very sharp. The S0(0) transition of p-H2 and o-D2 is a triplet of sharp lines, but the corresponding transition in HD is not split. The vibrational frequencies in the liquid are lowered by 7 to 9 cm−1 and in the solid by 8 to 11 cm−1 from the gas values. The Raman spectrum of p-H2 has been discussed in detail by Van Kranendonk. In the present communication the vibrational shifts in the various solids are correlated by representing them as the sums of shifts due to dispersion forces, overlap forces, and vibrational coupling.

The resonance Raman spectra and excitation profiles of some 4-sulfamylazobenzenes

1977 ◽  
Vol 55 (9) ◽  
pp. 1444-1453 ◽  
Author(s):  
Kamal Kumar ◽  
P. R. Carey
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Resonance Raman ◽  
Valence Bond ◽  
Wavelength Dependence ◽  
Accurate Estimation ◽  
Intensity Changes ◽  
Stretching Vibration ◽  
Resonance Raman Spectra ◽  
Frequency Changes

The resonance Raman spectra of three pharmacologically important sulfonamides, 4-sulfamyl-4′-dimethylaminoazobenzene (1), 4-sulfamyl-4′-hydroxyazobenzene (2), and 4-sulfamyl-4′-aminoazobenzene (3), are compared with those of analogues lacking the sulfonamide group. The —SO2NH2 moiety does not directly contribute intense or moderately intense bands to the resonance Raman spectra of 1, 2, and 3. However, —SO2NH2 ionization is reflected by frequency changes in a band near 1140 cm−1 and intensity changes in the 1420 cm−1 region. The normal Raman spectrum of 2 confirms that the intensity changes reflect —SO2NH2 ionization rather than unrelated changes in vibronic coupling. The effect of —OH ionization on the resonance Raman spectrum of 2 emphasizes that caution must be exercised when relating spectral perturbations to changes in contributions from valence bond type structures. Resonance Raman excitation profiles for the 1138, 1387, and 1416 cm−1 bands of 2 show that these bands gain intensity by coupling with the electronic transitions in the 240 to 450 nm region and that, more than 1000 cm−1 to the red of λmax, the wavelength dependence can be closely reproduced by the FB type terms of Albrecht and Hutley. The excitation profile for each band shows evidence for structure in the 470 nm region, although lack of sufficient excitation wavelengths prevents accurate estimation of the spacing. Under conditions of rigorous resonance the intense Raman lines all occur in the 1400 cm−1 region, i.e. they are 'bunched' in the region known to contain the —N=N— stretching vibration.

HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: I. EXPERIMENTAL METHODS

1954 ◽  
Vol 32 (5) ◽  
pp. 330-338 ◽  
Author(s):  
B. P. Stoicheff
Keyword(s):  
Raman Spectroscopy ◽  
High Resolution ◽  
Magnesium Oxide ◽  
Raman Spectra ◽  
Experimental Methods ◽  
Resolving Power ◽  
Polar Molecules ◽  
High Current ◽  
Rotational Constants ◽  
Moments Of Inertia

An apparatus for obtaining intense Raman spectra of gases excited by the Hg 4358 line is described. It consists of a mirror-type Raman tube irradiated by two high-current mercury lamps, completely enclosed in a reflector of magnesium oxide. The lamps are externally water-cooled along their entire length and emit sharp lines of high intensity.Rotational Raman spectra of gases at a pressure of 1 atm. have been photographed in the second order of a 21 ft. grating in exposure times of 6 to 24 hr. The Raman lines are sharp and a resolving power of about 100,000 has been achieved. It will be possible to resolve the rotational Raman spectra, and hence to evaluate the rotational constants of molecules having moments of inertia of up to 300 × 10−10 gm. cm.2 Such investigations will be especially useful for non-polar molecules.

High resolution spectra of GeH4v=6 and 7 stretch overtones. The perturbed local mode vibrational states

1993 ◽  
Vol 99 (4) ◽  
pp. 2359-2364 ◽  
Author(s):  
Qing‐Shi Zhu ◽  
A. Campargue ◽  
J. Vetterhöffer ◽  
D. Permogorov ◽  
F. Stoeckel
Keyword(s):  
High Resolution ◽  
Local Mode ◽  
Vibrational States
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