Liquid Argon Solutions Research Articles

Infrared spectroscopy of 2-methyl-2-butene in liquid argon solution and ab initio calculated vibrational frequencies

Abstract The infrared spectrum of 2-methyl-2-butene dissolved in liquid argon has been measured at 90 K. The absorption was obtained with a low-temperature cell and a Fourier transform spectrophotometer. The solubility of 2-methyl-2-butene in liquid argon was measured. Ab initio molecular orbital calculations were performed to obtain the equilibrium geometry, vibrational frequencies, and infrared intensities. The calculations were done at the Hartree-Fock level using the 6-31G ∗ split-valence basis set. A normal coordinate analysis was performed using a scaled force field determined from the 6-31G ∗ basis set. The potential energy distribution was also obtained.

Overtone Spectroscopy of CHD3 in Liquid Argon Solutions

AbstractThe vibrational overtone spectrum of CHD3 has been obtained in liquid argon solutions at temperatures around 94 K. The spectra of C‐H and C‐D overtones below 10000 cm−1 were obtained with a Fourier transform spectrophotometer operating in the near‐infrared region and a low temperature cell. The C‐H spectrum around Δv = 5 was recorded using a resonant photoacoustic technique at cryogenic temperatures. The absorption bands were computer deconvoluted to obtain the peak absorption frequency, the band‐width, and the area of some important bands. Due to the small frequency shift of the absorption bands in solution with respect to the gas phase frequencies, the assignment of the transitions was made by comparison with experimental and calculated gas phase frequencies. The calculation of gas phase frequencies and vibrational states was made using the pure local mode model for the isolated C‐H bond and the Harmonically Coupled Anharmonic Oscillator (HCAO) model for the three equivalent C‐D bonds. In order to test the Fermi resonance interaction between C‐H stretching and bending vibrations, the absorption bands and relative intensities in solution were used to obtain the parameters of an effective Fermi resonance Hamiltonian. The values of the parameters obtained in solution and gas phase are very close in magnitude. The optimized parameters of the Fermi resonance Hamiltonian give a good description of the frequencies and relative intensities of the C‐H absorption bands in solution.

Vibrational Spectroscopy of C-H Bonds of C2H4 Liquid and C2H4 in Liquid Argon Solutions

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVibrational Spectroscopy of C-H Bonds of C2H4 Liquid and C2H4 in Liquid Argon SolutionsAnsgar Brock, Nairmen Mina-Camilde, and Carlos ManzanaresCite this: J. Phys. Chem. 1994, 98, 18, 4800–4808Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://doi.org/10.1021/j100069a006RIGHTS & PERMISSIONSArticle Views150Altmetric-Citations31LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (887 KB) Get e-Alerts

Vibrational spectroscopy of CH bonds of methane and tetramethylsilane in liquid argon solutions

The liquid phase spectra of the fundamental and first overtone (Δ v = 1, 2) around the CH stretch of methane and tetramethylsilane in liquid argon solutions have been measured using Fourier transform IR and near-IR techniques. The fourth overtone (Δ v = 5) of the CH stretch has been measured in methane pure at 116 K and in liquid argon solutions at 100 K using laser excitation with acoustic detection. The results indicate that absorption bands, which normally present extensive inhomogeneous congestion, could be simplified by studying the absorptions in diluted solutions at low temperatures with inert liquefied gases as solvents.

An infrared study of monomeric and oligomeric (n=2, 3, and 4) hydrogen chloride in liquified noble gases

Infrared spectra (3100–2600 cm−1) of HCl dissolved in liquid argon (94–124 K), liquid krypton (117–167 K), and liquid xenon (161–221 K) at concentrations varying from 0.8×10−3 to 2.8×10−2 M are reported. At low concentrations in all three solvents, only the spectrum due to monomeric species is observed. For solutions in liquid argon, the observed rotational fine structure was assigned. For all solvents, the monomeric stretching frequency shows a linear relation to the relative density of the solvent, extrapolating to the dilute vapor phase frequency. At higher concentrations in liquid argon and liquid krypton, bands due to oligomeric species are found. Factor analysis shows at least three oligomeric species are present. The band profile analysis of the oligomer absorptions allows the assignment of observed bands to dimer, trimer, and tetramer. From the temperature dependence of the oligomer band intensities, the enthalpy difference for dimerization is found to be 3.78±0.33 kJ mol−1 in liquid argon and 5.09±0.55 kJ mol−1 in liquid krypton. The trimerization and tetramerization enthalpy differences in liquid argon were measured to be 12.6±1.9 and 18.7±3.2 kJ mol−1, respectively.

Quantitative analysis of sulfur hexafluoride for molecular impurities using IR absorption spectra of solutions in liquid argon

Quantitative analysis of sulfur hexafluoride for molecular impurities using IR absorption spectra of solutions in liquid argon

On the conformational analysis of methyl cyanoacetate

Ab initio calculations with full geometry optimization at the 4-21G level show that methyl cyanoacetate, NCCH 2COOCH 3, can exist as the cis (τ=0°) or as the gauche (τ= 145°) conformer, where τ measures the (N)CC(H 2)CO dihedral angle. The cis is calculated to be 3.92 kJ mol −1 more stable than the gauche. Mid infrared spectra of the vapor and solid (77 K) phases and of solutions in liquid argon (80 K) along with Raman spectra of the liquid phase of the undeuterated molecule and of NCCH 2COOCD 3 are reported and assigned. Asymmetric top contour simulations show that in the vapor phase the gauche form is the more stable of the two conformers observed. Low temperature Raman spectra of the liquid phase show that the enthalpy difference between the conformers is 2.46±0.2 kJ mol −1, favoring the cis conformer.

Non-and near-resonant (vv) energy transfer between the isotopes of N 2 and of CO in liquid Ar and in the gas phase at 85 k

Rate constants for vibrational energy transfer have been measured in the system N 2( v= 1) +CO( v=0) as a function of energy mismatch by using isotopic derivatives of N 2 and of CO. These rate constants have been determined both in the gas phase and in liquid argon solution at 85 K. For non-resonant processes we find k L= k G for the nearest to resonant system we find k L < k G. This result is considered to arise because long range forces important in near-resonant energy transfer operate to a lesser extent in the liquid phase.

A comparison of rate constants for vibrational relaxation in liquid argon and in the gas phase at the same temperature

Rate constants for non-resonant VV transfer from 12CO(v = 1) to O2, CH4 and N2; from 13CO(v = 1) to O2 and N2; and from N2(v = 1) to CH4 have been measured in liquid-argon solutions at 85 K. The results are compared with those obtained in the gas phase at the same temperature in this laboratory. In all cases the rate constants are the same in both phases within 10%. These results are at variance with the predictions of cell theory and cannot be accounted for adequately by the statistical theory of Delalande and Gale. Calculations are presented which show that collisions with remarkably low energies of ≈ 100 cm−1 (150 K) dominate the energy transfer processes at these low temperatures. However it is concluded that the isolated binary collision model is still applicable.

Infrared spectroscopy of simple molecules in liquid-argon solution—III. The determination of the anharmonic force constants of OCS

The i.r. spectrum of OCS has been measured in liquid-argon solution and thirty three vibrational bands have been assigned. The vibrational wavenumbers, measured in liquid-argon solution, have been used to calculate the anharmonic (cubic and quartic) internal-coordinate force constants of OCS; the results are compared with previous calculations using gas-phase data.

Infrared spectra of tetrafluorohydrazine solutions in liquefied gases

The IR spectra of N 2F 4 solutions in liquid argon and nitrogen have been recorded and reanalyzed in the 3300–3550 cm −1 region. The fundamental absorption bands of NF-stretching modes of both the gauche and trans isomers and the bands of the second order transition have been observed. These new IR data on the spectra of cryosystems and published Raman data allowed us to make an unambiguous interpretation of the NF 2-stretching vibrational bands for both the N 2F 4 conformers.

Vibrational anharmonicity in CF4

A simple anharmonic force field, consisting of a general quadratic force field in curvilinear coordinates, augmented with principal cubic and quartic valence-bond stretching force constants based on a Morse function, has been determined by least-squares adjustment to the vibrational energies of CF4. Since this model did not give a value of the cubic normal-coordinate force constant k344 in agreement with experiment, we considered a second force field identical to the first one except for the introduction of cubic stretch–bend–bend interaction force constants. These force fields have been used to calculate the tetrahedral anharmonic splittings of overtone and combination levels of CF4 and the calculated splittings have been compared with observed values determined by re-examining the previously published infrared spectra of CF4 in liquid–argon solution.

A 2 m cell for infrared spectroscopy in liquid—argon solution

A multiple reflection cell has been designed and built for the study of the infrared spectra of molecules in liquid—argon solution with long absorbing paths. The cell has been operated at path lengths from 0.3–2.1 m although, in principle, longer paths may be obtained. The volume of the cell is about 1.5 1. When set to a path length of 1.5 m the transmission of the cell in regions of no solute absorption was found to be better than 95%.

Infrared spectra of simple molecules in liquid-argon solution—II. NF 3 and N 2O

The i.r. spectrum of NF 3 has been measured in liquid-argon solution. Since the sample of NF 3 used for the experiments was contaminated with N 2O, it was also necessary to measure the spectrum of N 2O in liquid-argon solution so that the impurity bands could be identified unambiguously. In the observed spectrum of NF 3 it was possible to identify 29 overtone and combination bands in addition to the vibrational fundamentals. The measured wavenumbers of the NF 3 bands have been used to estimate the anharmonic coefficients x ss′, which are compared with the corresponding quantities determined from the gas-phase spectrum.

Intensities of binary overtone and combination bands in the i.r. spectrum of NF 3

The intensities of the binary overtone and combination bands in the i.r. spectrum of NF 3 have been measured in the gas phase and in liquid—argon solution. The observed intensities have been interpreted in terms of a simple model which ascribes all the intensity of the binary overtones and combinations to anharmonic coupling with the fundamentals; i.e., a model in which the second derivatives of the dipole moment with respect to the normal coordinates are assumed to be zero. The agreement between the observed intensities and the calculated ones is extremely good for the bending modes but less satisfactory for the stretching modes. The use of a polar-tensor model to predict the intensities of the vibrational fundamentals is also explored.

Raman spectrum of CF 4 in liquid-argon solution

Raman spectra of CF 4 in liquid-argon solutions have been measured and compared to spectra of the liquid and the gas. The Fermi doublet between ν 3 and 2ν 4 was investigated as a function of concentration, and changes in the Raman spectrum corresponded closely to those observed previously in the i.r. spectrum.

Infrared spectra of simple molecules in liquid-argon solution—I. CF4

Abstract The infrared spectra of solutions of CF 4 in liquid argon have been measured using a cell with a 4 cm optical path. A large number of overtone and combination bands have been observed and assigned. The technique promises to yield vibrational information useful in the calculation of anharmonic force constants.

Polymer production in the .gamma.-radiolysis of methane, ethane, and ethylene solutions in liquid argon

Polymer production in the .gamma.-radiolysis of methane, ethane, and ethylene solutions in liquid argon

The 0-2 Transition of CO in Condensed Oxygen, Nitrogen, and Argon.

Infrared absorption spectra of CO in the region of the first overtone have been observed in dilute (approximately 1 to 10 parts in 1000) liquid solutions of oxygen, nitrogen, and argon, and clear crystalline nitrogen and argon matrices. The overtone band was found at 4249.0, 4252.4, and 4252.0 cm−1 with half widths of 18.4, 17.8, and 13.7 cm−1 in liquid oxygen, nitrogen, and argon solutions at 82, 78, and 82 °K, respectively. The half width in liquid oxygen varied from 18.4 to 10.0 cm−1 in the temperature range 82 to 57 °K. The band position was the same but its width was smaller in the crystalline nitrogen matrix. Two bands were observed in the clear crystalline argon solid at 4245 and 4256 cm−1. The solution results cannot be interpreted with the recent theory of Buckingham.