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.

Pressure shifts in the vibrational Raman spectra of hydrogen and deuterium, 315–85 K

1978 ◽  
Vol 56 (8) ◽  
pp. 1102-1108 ◽  
Author(s):  
E. C. Looi ◽  
J. C. Stryland ◽  
H. L. Welsh
Keyword(s):  
Standard Deviation ◽  
Raman Spectra ◽  
Rotational Level ◽  
The Other ◽  
Dispersion Forces ◽  
Temperature Dependent ◽  
Vibrational Coupling ◽  
Frequency Shifts ◽  
Linear Coefficient ◽  
Gas Density

The Raman frequencies of the Q(J) lines of the fundamental Raman bands of compressed H2 and D, were measured with a standard deviation of ±0.02 cm−1 at gas densities from 10 to 100 amagat at several temperatures in the range 315 to 85 K. The frequency shifts are negative and linear in the gas density; they range up to −1.2 cm−1 for H2 and −0.7 cm−1 for D2. The linear coefficient for the Q(J) line has the form, ai + ac(nJ/n), where nJ/n is the fractional population of the rotational level, J, and ai and ac are constants independent of J. The constant ai is strongly temperature-dependent and is interpreted as the vibrational shift due to isotropic dispersion and overlap forces. On the other hand, ac is practically temperature-independent and is believed to arise from vibrational coupling through dispersion forces.

Preresonance Raman spectra and excitation profiles of some chemically and isotopically substituted trans-4-benzylideneoxazolin-5-ones

1978 ◽  
Vol 56 (2) ◽  
pp. 240-245 ◽  
Author(s):  
D. J. Phelps ◽  
R. G. Carriere ◽  
K. Kumar ◽  
P. R. Carey
Keyword(s):  
Raman Spectrum ◽  
Absorption Band ◽  
Raman Spectra ◽  
Phenyl Group ◽  
Low Energy ◽  
Coupling Scheme ◽  
Raman Intensity ◽  
Vibrational Coupling ◽  
Intensity Enhancement ◽  
Phenyl Rings

Resonance and preresonance Raman spectra of nine substituted trans-4-benzylidene- Δ2-oxazolin-5-ones are reported. The seven analogs with phenyl in the 2 position of the oxazolinone ring have either an electron donating or attracting group on one of the phenyl rings. Although shifts in λmax of up to 100 nm are observed the Raman spectra are very similar to that of the unsubstituted trans isomer. However, in the substituted compounds modes from the benzylidene portion may become weakly intensity enhanced. Replacing the 2-phenyl group by 2-methyl in the oxazolinone ring results in quite gross changes in the Raman spectrum. Substitution by 15N in the ring of a 2-methyloxazolinone reveals that a change in the vibrational coupling scheme occurs. Excitation profiles for the 2-phenyl and the 2-methyl analogs of 4-(p-nitrobenzylidene)oxazolinone indicate that in each compound ail intensity enhanced modes are coupled to the intense low energy absorption band near 350 nm and the intensity enhancement fits the FB2 terms of Albrecht and Hutley. However, differences in the relative intensity of the benzylidene nitro feature in the 2-methyl and 2-phenyl analogs, taken with the excitation profiles, suggest that in the 2-methyl compound the electronic transition responsible for Raman intensity enhancement is no longer primarily located in the C=C—N=C—Ph moiety.

Vibrational Raman spectra of liquid and solid ethylene

1970 ◽  
Vol 48 (5) ◽  
pp. 513-520 ◽  
Author(s):  
S. M. Blumenfeld ◽  
S. Paddi Reddy ◽  
H. L. Welsh
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Force Constant ◽  
Raman Spectra ◽  
Short Range ◽  
Short Range Order ◽  
Freezing Point ◽  
Low Frequency ◽  
Intermolecular Force ◽  
Linear Dispersion

The Raman spectra of liquid and solid C2H4 have been examined at a reciprocal linear dispersion of 8 cm−1/mm. The liquid spectrum presents some evidence of short-range order in the liquid near the freezing point. The gerade fundamentals and low-frequency librational modes have been observed in the Raman spectrum of the solid. Analysis of the observed splitting in terms of H-atom repulsion indicates that the intermolecular force constant is 950 dyn/cm, and the crystal structure is P21/n1. The origin of other observed structures is uncertain.

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.

Vibrational spectra of ammonium ammine-oxo-diperoxovanadate

1982 ◽  
Vol 47 (6) ◽  
pp. 1549-1555 ◽  
Author(s):  
Peter Schwendt ◽  
Miloslav Pisárčik
Keyword(s):  
Raman Spectrum ◽  
Bond Length ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Normal Coordinate Analysis ◽  
Wave Number ◽  
Infrared And Raman Spectra ◽  
Normal Coordinate ◽  
Mass Model ◽  
Vibrational Coupling

Infrared and Raman spectra of solid NH4[VO(O2)2NH3], ND4[VO(O2)2ND3], 14/15NH4[VO(O2)214/15NH3] (about 50% 15N) and Raman spectrum of solution of NH4[VO(O2)2NH3] have been measured. Interpretation of the spectra was complemented by normal coordinate analysis in the approximation of point mass model (NH3). The results have shown that there exists coupling of vibrations of two V(O2) groups, which enables an explanation of differences between spectra of the mono- and diperoxo complexes. The vibrational coupling of VO and OO bonds within one V(O2) group probably causes small sensitivity of wave number of v(O-O) band to changes of d(O-O) bond length.

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 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 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.

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.

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