Effect of collisions on line profiles in the vibrational spectrum of molecular hydrogen

Kelley, J. Daniel; Bragg, S. L.

doi:10.1103/physreva.34.3003

Cited by 27 publications

(9 citation statements)

References 43 publications

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“…To the best of our knowledge, the derived pressure-shift coefficients are the most accurate determinations for H 2 transitions. The pressure-shift coefficients of the (3-0) band have been predicted by Kelley & Bragg (1986), but their values are about 50% larger than ours.…”

Section: Resultscontrasting

confidence: 74%

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H₂NEAR 0.8 μm

Pan

Cheng

et al. 2012

ApJ

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The very weak S(0)-S(3) electric quadrupole transitions of the second overtone band of molecular hydrogen have been recorded in the laboratory by continuous-wave cavity ring-down spectroscopy near 0.8 μm. The ultrahigh sensitivity of the spectrometer (α min ∼ 1 × 10 −10 cm −1 ) allows us to detect the considered transitions at a relatively low sample pressure (50-750 torr). The line positions, intensity, and pressure-shift coefficients are derived from a fit of the line shape using a Galatry profile. Compared with literature values, the relative differences between the experimental and theoretical transition intensities are reduced by one order of magnitude, reaching a value of about 2% mainly dependent of the line-shape function adopted for the profile fitting. The thermal equilibrium relative intensity of the S(1) to S(0) line is determined with an accuracy of 0.4%, which can be used to probe the ortho-to para-H 2 concentration ratio. Our measurements confirm the quality of the high-level ab initio calculations, including the relativistic and quantum electrodynamics corrections.

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Section: Resultscontrasting

confidence: 74%

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H₂NEAR 0.8 μm

Pan

Cheng

et al. 2012

ApJ

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“…Kelley and Bragg have used a semi-classical approach to predict the line shifts as a function of the upper rovibrational states. 24 For the (2-0) O(2) and O(3) lines, they obtained À3.6 Â 10 À3 and À3.3 Â 10 À3 cm À1 per amagat, respectively, in very good agreement with our experimental values.…”

Section: Line Profile Analysis and Intensities Derivationsupporting

confidence: 87%

The absorption spectrum of H₂: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35 000 cm⁻¹

Campargue

Kassi

Pachucki

et al. 2012

Phys. Chem. Chem. Phys.

104

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Five very weak transitions-O(2), O(3), O(4), O(5) and Q(5)-of the first overtone band of H(2) are measured by very high sensitivity CW-Cavity Ring Down Spectroscopy (CRDS) between 6900 and 7920 cm(-1). The noise equivalent absorption of the recordings is on the order of α(min)≈ 5 × 10(-11) cm(-1) allowing for the detection of the O(5) transition with an intensity of 1.1 × 10(-30) cm per molecule, the smallest intensity value measured so far for an H(2) absorption line. A Galatry profile was used to reproduce the measured line shape and derive the line strengths. The pressure shift of the O(2) and O(3) lines was accurately determined from a series of recordings with pressure ranging between 10 and 700 Torr. From an exhaustive review of the literature data, the list of H(2) absorption lines detected so far has been constructed. It includes a total of 39 transitions ranging from the S(0) pure rotational line near 354 cm(-1) up to the S(1) transition of the (5-0) band near 18,908 cm(-1). These experimental values are compared to a highly accurate theoretical line list constructed for pure H(2) at 296 K (0-35,000 cm(-1), intensity cut off of 1 × 10(-34) cm per molecule). The energy levels and transition moments were computed from high level quantum mechanics calculations. The overall agreement between the theoretical and experimental values is found to be very good for the line positions. Some deviations for the intensities of the high overtone bands (V > 2) are discussed in relation with possible pressure effects affecting the retrieved intensity values. We conclude that the hydrogen molecule is probably a unique case in rovibrational spectroscopy for which first principles theory can provide accurate spectroscopic parameters at the level of the performances of the state of the art experimental techniques.

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“…We adjusted D = 4.39 × 10 −6 cm −1 /(m/s) to reproduce for the SD e BBP fit a value of ∆ consistent with recently measured collisional shifting coefficient −3.7 × 10 −3 cm −1 amagat −1 . 70 Similar value was reported by Kelley and Bragg 71 and is just between other experimental results. 90,91 …”

Section: Appendix B: Autocorrelation Functions For Hard and Soft Collsupporting

confidence: 81%

Velocity-changing collisions in pure H2 and H2-Ar mixture

Wcisło

Tran

Kassi

et al. 2014

The Journal of Chemical Physics

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We show how to effectively introduce a proper description of the velocity-changing collisions into the model of isolated molecular transition for the case of self-and Ar-perturbed H 2 . We demonstrate that the billiardball (BB) approximation of the H 2 -H 2 and H 2 -Ar potentials gives an accurate description of the velocitychanging collisions. The BB model results are compared with ab initio classical molecular dynamics simulations (CMDS). It is shown that the BB model correctly reproduces not only the principal properties such as frequencies of velocity-changing collisions or collision kernels, but also other characteristics of H 2 -H 2 and H 2 -Ar gas kinetics like rate of speed-changing collisions. Finally, we present line-shape measurement of Q (1) line of the first overtone band of self-perturbed H 2 . We quantify the systematic errors of line-shape analysis caused by the use of oversimplified description of velocity-changing collisions. These conclusions will have significant impact on recent rapidly developing ultra-accurate metrology based on Doppler-limited spectroscopic measurements like Doppler-width thermometry, atmosphere monitoring, Boltzmann constant determination or transition position and intensity determination for fundamental studies.

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Effect of collisions on line profiles in the vibrational spectrum of molecular hydrogen

Cited by 27 publications

References 43 publications

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H₂NEAR 0.8 μm

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H₂NEAR 0.8 μm

The absorption spectrum of H₂: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35 000 cm⁻¹

Velocity-changing collisions in pure H2 and H2-Ar mixture

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Effect of collisions on line profiles in the vibrational spectrum of molecular hydrogen

Cited by 27 publications

References 43 publications

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H2NEAR 0.8 μm

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H2NEAR 0.8 μm

The absorption spectrum of H2: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35 000 cm−1

Velocity-changing collisions in pure H2 and H2-Ar mixture

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Product

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THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H₂NEAR 0.8 μm

THEv= 3 ← 0S(0)-S(3) ELECTRIC QUADRUPOLE TRANSITIONS OF H₂NEAR 0.8 μm

The absorption spectrum of H₂: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35 000 cm⁻¹