Fundamental and Overtone Vibrational Transitions in the Raman Spectrum of h.c.p. Solid Hydrogen

1972 ◽  
Vol 50 (13) ◽  
pp. 1471-1479 ◽  
Author(s):  
William R. C. Prior ◽  
Elizabeth J. Allin
Keyword(s):  
Raman Spectrum ◽  
Relative Intensity ◽  
Argon Laser ◽  
Solid Hydrogen ◽  
Frequency Separation ◽  
Frequency Change ◽  
Quadrupolar Interaction ◽  
Vibrational Coupling ◽  
Frequency Shifts ◽  
Vibrational Overtone

The use of an argon laser of high intensity has made it possible to observe the vibrational overtone of solid hydrogen and to study the fundamental over a wider concentration range than previously. At ortho concentrations below ~ 15% the Q1(1) line has two components. The dependence on concentration and temperature of the frequency separation and relative intensity of these components is accounted for by the quadrupolar interaction between ortho molecules. Differences in the frequency shifts of the Q1(0) and the Q1(1) and of the Q2(0) and the Q1(1) lines in mixtures of all concentrations are also related to the quadrupolar interactions. The overtone lines show almost no frequency change with concentration. This is explained by a much smaller vibrational coupling due to the isotropic interactions in the ν = 2 than in the ν = 1 state. Confirmation of this is found in the small enhancement of the intensity of Q2(1) relative to Q2(0). The measurement of the frequency of Q2(0) makes it possible to determine the parameters μ1, and μ2, specifying the change in the intramolecular potential by the isotropic interactions, from transitions involving J = 0 states alone.

The vibrational Raman spectrum of compressed solid hydrogen

1979 ◽  
Vol 57 (3) ◽  
pp. 442-448 ◽  
Author(s):  
E. J. Allin ◽  
S. M. Till
Keyword(s):  
Raman Spectrum ◽  
Excitation Energy ◽  
Solid Hydrogen ◽  
Vibrational Coupling ◽  
Angular Momenta ◽  
Type Interaction

The frequencies of the pure vibrational lines, Q(0) and Q(1), in the Raman spectrum of solid H2 have been measured when the solid was subjected to a number of pressures between 400 and 1000 kg cm−2, corresponding to solid densities up to ~ 1250 amagat. Most samples studied had orthohydrogen concentrations ≥ 0.60. For these the frequency of Q(0) increased as the density increased but that of Q(1) showed little change. This can be explained if it is assumed that (i) the isotropic repulsive overlap interaction between a pair of molecules increases more rapidly than the attractive dispersion-type interaction, (ii) the effect of vibrational coupling between molecules in the same J-state increases asp2, and (iii) the lowering of the excitation energy of the ν = 1,J = 1 stale by electric quadrupolar interactions increases as ρ5/3. There is evidence that at higher densities ordering of the molecular angular momenta may occur at temperatures up to 4 K. The intensity of Q(1) relative to Q(0) is further enhanced at higher densities.

The Raman spectrum of solid hydrogen

1965 ◽  
Vol 26 (11) ◽  
pp. 615-620 ◽  
Author(s):  
E.J. Allin ◽  
A.H. M ◽  
V. Soots ◽  
H.L. Welsh
Keyword(s):  
Raman Spectrum ◽  
Solid Hydrogen

Formation Of Hydrogen Molecules In Crystalline Silicon Treated With Atomic Hydrogen

1996 ◽  
Vol 442 ◽  
Author(s):  
K. Murakami ◽  
N. Fukata ◽  
S. Sasaki ◽  
K. Ishioka ◽  
K. G. Nakamura ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Room Temperature ◽  
Crystalline Silicon ◽  
Molecular Gas ◽  
Frequency Shifts ◽  
Hydrogen Molecules ◽  
Solid Phases ◽  
Liquid And Solid Phases ◽  
Pressure Hydrogen ◽  
Rule Out

AbstractHydrogen molecules have been formed in crystalline silicon at various temperatures by a hydrogen-atom remote treatment. The Raman spectrum of the vibrational lines of hydrogen molecules in crystalline silicon is detected for silicon samples treated at temperatures between 250 and 500° C. The maximum production is obtained at 400° C. The Raman spectrum of hydrogen molecules in silicon observed at room temperature exhibits a frequency shift of around 4158 cm−1 and a very broad half-width of approximately 34 cm−1. Isotope shift also can be observed at around 2990 cm−1 in silicon treated with deuterium atoms at 400° C. The frequency shifts of the observed lines are in close agreement with those reported for molecular hydrogen and deuterium in gas, liquid, and solid phases. We discuss a model for the hydrogen molecule configuration and rule out the possibility of high-pressure hydrogen molecular gas in microvoids in crystalline silicon. These results indicate that hydrogen molecules exist at the tetrahedral interstitial sites in crystalline silicon.

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.

scholarly journals The Raman spectrum of rock-salt

1946 ◽  
Vol 187 (1009) ◽  
pp. 188-196 ◽  
Keyword(s):  
Raman Spectrum ◽  
Rock Salt ◽  
Lattice Dynamics ◽  
Vibration Spectrum ◽  
Raman Effect ◽  
Frequency Shifts ◽  
Crystal Lattices ◽  
Absorption Frequency ◽  
Infra Red ◽  
Quartz Spectrograph

Using a non-luminescent crystal of rock-salt, a quartz spectrograph with a fine slit, and the 2536.5 A resonance radiations of mercury arc as exciter, the Raman effect in rock-salt has been studied. The spectrum exhibits nine distinct Raman lines with frequency shifts 135, 184, 202, 235, 258, 278, 314, 323 and 350 cm. -1 . The frequency shifts 235 and 184 cm. -1 representing conspicuous lines in the Raman spectrum agree as nearly as could be expected with the position of the two subsidiary infra-red absorption maxima observed by Barnes & Czerny with thin films of rock-salt. The principal infra-red absorption frequency of 163 cm. -1 is inactive in the Raman effect, but its octave is represented. The nature of the Raman spectrum to be expected is deduced on the basis of a theory due to Tamm, as also on the basis of another due to Fermi, the vibration spectrum of the rock-salt lattice being taken to be that worked out by Kellermann on the basis of the Born lattice dynamics. The results are altogether of a different nature from those actually observed experimentally in the present investigation. The conclusion is thus reached that the Born lattice dynamics does not correctly picture the vibration spectrum of the rock-salt lattice. On the other hand the observed facts, both in respect of Raman effect and infra-red absorption, fit into the theoretical picture provided by the dynamics of crystal lattices recently worked out by Sir C. V. Raman.

DENSITY EFFECTS IN THE RAMAN SPECTRUM OF CARBON DIOXIDE

1952 ◽  
Vol 30 (2) ◽  
pp. 99-110 ◽  
Author(s):  
H. L. Welsh ◽  
P. E. Pashler ◽  
B. P. Stoicheff
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Raman Spectrum ◽  
Relative Intensity ◽  
Intermolecular Forces ◽  
Anisotropic Scattering ◽  
Fermi Resonance ◽  
Intensity Effect ◽  
Density Effects ◽  
Frequency Changes

Two Raman tubes, one of quartz and one of glass, capable of withstanding pressures up to 75 and 300 atm. respectively, were used to study density effects in the Raman spectrum of carbon dioxide. The components of the ν1 band show changes in frequency and relative intensity with increasing density. An analysis shows that the frequency changes are due to a lowering of the frequency of 2ν2, in Fermi resonance with ν1, with increasing density. The intensity effect, however, is not completely explained by the change in the sharpness of the resonance. In the high pressure gas and in the liquid faint bands corresponding to the Raman inactive frequencies, ν2 and ν3, are observed. The effect of increasing density on the rotational Raman spectrum can be explained in terms of the broadening of anisotropic scattering by intermolecular forces.

Raman spectrum of solid hydrogen deuteride

1993 ◽  
Vol 47 (22) ◽  
pp. 14886-14897 ◽  
Author(s):  
J. J. Miller ◽  
R. L. Brooks ◽  
J. L. Hunt
Keyword(s):  
Raman Spectrum ◽  
Solid Hydrogen ◽  
Hydrogen Deuteride

AN INTENSITY ANOMALY IN THE RAMAN SPECTRA OF SOLID AND LIQUID HYDROGEN AND DEUTERIUM

1967 ◽  
Vol 45 (11) ◽  
pp. 3589-3595 ◽  
Author(s):  
A. H. Mckague Rosevear ◽  
G. Whiting ◽  
Elizabeth J. Allin
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Molecular Interaction ◽  
Intensity Ratio ◽  
Liquid Hydrogen ◽  
Solid Hydrogen ◽  
Solid Deuterium ◽  
Number Ratio ◽  
Measured Ratio

In the absence of molecular interaction the ratio of the intensity of the Q1(1) to that of the Q1(0) vibrational line in the Raman spectrum of solid hydrogen should be equal to the ratio of the number of ortho to the number of para molecules. The measured ratio at 2 °K has been found to be two to three times greater than this (Soots et al. 1965). The same anomaly is shown to be present at ~13.5 °K and also in the spectrum of the liquid. In the spectrum of solid deuterium the anomaly is much greater; the intensity ratio varies from 9.3 times the number ratio for n-D2 to 50 times the number ratio for 3.7% para-D2. The S1(0) and S1(1) lines do not show any corresponding anomaly. The experimental observations can be explained by the theory of vibrational interaction between ortho and para molecules developed recently by James and Van Kranendonk (1967a, b).

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