Raman intensities. Part 9.—Vibrational intensities for spherically symmetric modes of CH4, CD4, CF4, SiF4, SF6, SeF6and TeF6

Long, D. A.; Thomas, E. L.

doi:10.1039/tf9635901026

Cited by 25 publications

(3 citation statements)

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“…They are gathered in Table VI. The value of ∂ ᾱ/∂q 1 is known to a good accuracy both experimentally 63 and numerically (on the basis of second-order Møller-Plesset perturbation theory) 19 but given the poor accuracy of k 155 , the ∂ 2 ᾱ/∂q 2 5 values are given to three decimal places.…”

Section: A Derivativesmentioning

confidence: 99%

From light-scattering measurements to polarizability derivatives in vibrational Raman spectroscopy: The 2ν5 overtone of SF6

Kremer

Rachet

Chrysos

2013

The Journal of Chemical Physics

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The room-temperature isotropic spectrum of SF6 was recorded at the frequency of the 2ν5 overtone by running high-sensitivity incoherent Raman experiments for two independent polarizations of the incident beam and for gas densities varying from 2 to 27 amagat. Weak yet observable pressure effects were found. A transparent analysis of the Raman cross-section problem along with the first-ever prediction of the value of the mean polarizability second derivative ∂(2)α/∂q5(2) are made and the hitherto underestimated role of the hot bands of SF6 is brought to the wider public. The emergence of an analytic hotband factor is shown whose magnitude is dramatically increased with the order of the overtone and the gas temperature and all the more so upon considering low-frequency molecular vibrations. Our formulas, which in the harmonic approximation are exact, are still applicable to real situations provided certain conditions are fulfilled. For nondegenerated modes, generalization to higher order overtones is made, an issue addressing the much challenging problem of the IR-allowed second overtone bands. The content of this paper is also an invitation towards ab initio derivative-calculations for sulfur hexafluoride, especially given the today's needs in interpreting spectra of significance for greenhouse atmospheric issues.

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Section: A Derivativesmentioning

confidence: 99%

From light-scattering measurements to polarizability derivatives in vibrational Raman spectroscopy: The 2ν5 overtone of SF6

Kremer

Rachet

Chrysos

2013

The Journal of Chemical Physics

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“…The Raman scattering cross-section ratio of CO 2 measured before is used to estimate the component concentrations of O 2 and SO 2 , which results in a relatively large discrepancy with the stated values in the reference gas samples. Long et al reported the relative Raman intensity of CF 4 (ν 1 , 909 cm –1 ) related to CH 4 (ν 1 , 2917 cm –1 ). Furthermore, considering the correction of the effect of the high-reflectivity mirror and using CO 2 as the internal standard gas, we gave an estimated content of CF 4 .…”

Section: Applicationsmentioning

confidence: 99%

Multiple Gas Detection by Cavity-Enhanced Raman Spectroscopy with Sub-ppm Sensitivity

Yang

Tan

Qu³

et al. 2023

Anal. Chem.

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Accurate and sensitive detection of multicomponent trace gases below the parts-per-million (ppm) level is needed in a variety of medical, industrial, and environmental applications. Raman spectroscopy can identify multiple molecules in the sample simultaneously and has excellent potential for fast diagnosis of various samples, but applications are often limited by its sensitivity. In this contribution, we report the development of a cavity-enhanced Raman spectroscopy instrument using a narrow-line width 532 nm laser locked with a high-finesse cavity through a Pound-Drever-Hall locking servo, which allows continuous measurement in a broad spectral range. An intracavity laser power of up to 1 kW was achieved with an incident laser power of about 240 mW, resulting in a significant enhancement of the Raman signal in the range of 200–5000 cm–1 and a sub-ppm sensitivity for various molecules. The technique is applied in the detection of different samples, including ambient air, natural gas, and reference gas of sulfur hexafluoride, demonstrating its capability for the quantitative measurement of various trace components.

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“…While the expression for the isotropic invariant of the second dipole hyperpolarizability of N 2 given by Maroulis agrees with that reported in [7], in the case of SF 6 the two authors have reported two different expressions; however, both expressions lead to the same formal result when the molecules are treated as point-polarizable particles, which is the model used throughout this paper (see [8]). For the first polarizability derivative of SF 6 , the experimental value was taken [18], even though ab initio results for self-consistent field (SCF) or MP2 level are also available [16]. For the quadrupole polarizability derivative, the MP2 value of [16] was used.…”

Section: A Trace and Momentsmentioning

confidence: 99%

Evidence for an isotropic signature in double vibrational collision-induced Raman scattering: A point-polarizable molecule model

Chrysos

Verzhbitskiy

2010

Phys. Rev. A

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The particularly weak isotropic spectrum of the recently reported [Verzhbitskiy et al., Phys. Rev. A 81, 012702 (2010)] nearly depolarized collision-induced Raman scattering band SF 6 (ν 1 ) + N 2 (ν 1 ) at room temperature was obtained and is presented here. The spectrum was extracted from high-quality measurements of two independent incident-field polarization scattering components. Its zero-order moment was found to be about 200 times smaller than that of its anisotropic counterpart. Agreement, both in spectral shape and in intensity, was found with predictions based on the dipole-induced dipole polarization model once corrected for the very substantial backinduction, dispersion, and dipole-induced quadrupole-induced dipole interaction mechanisms, all of which were considered within the model framework of two point-polarizable molecules. Quantum-mechanical calculations revealed a large contribution from bound and predissociating dimers that amounts to more than one-third of the total isotropic scattering intensity.

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Raman intensities. Part 9.—Vibrational intensities for spherically symmetric modes of CH₄, CD₄, CF₄, SiF₄, SF₆, SeF₆and TeF₆

Abstract: Measurements of the vibrationalRaman intensities for the vl(u1) modes of C D 4 , CF4, SiF4, SF6, SeF6 and TeF6 dl in the gaseous state relative to the VI (UI ) mode of c& are reported. Values of derived bond polarizabilities are calculated and discussed.

Cited by 25 publications

References 0 publications

From light-scattering measurements to polarizability derivatives in vibrational Raman spectroscopy: The 2ν5 overtone of SF6

From light-scattering measurements to polarizability derivatives in vibrational Raman spectroscopy: The 2ν5 overtone of SF6

Multiple Gas Detection by Cavity-Enhanced Raman Spectroscopy with Sub-ppm Sensitivity

Evidence for an isotropic signature in double vibrational collision-induced Raman scattering: A point-polarizable molecule model

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