H2-broadening coefficients in the ν2 and ν4 bands of PH3

Collisional broadening and line intensities in the ν2 and ν4 bands of PH3

“…6, c 0 ðJ ; KÞ increases slightly with K to a maximum, then decreases to rather low values for K approaching or equal to J . This behavior has also been observed for H 2 -and He-broadening coefficients of PH 3 [13,28] and a very simple physical interpretation has been given in [28]: for K ¼ J the molecule rotates about its principal symmetry axis (the z-axis), whereas for smaller K the rotation axis no longer coincides with z and the rotational states have a shorter life duration, yielding thus larger broadening. In Fig.…”

“…The typical values of c Dt and c D are, respectively, 1.12 and 1.20 Â 10 À3 cm À1 . In the SDRP we have considered q ¼ 4 corresponding to preponderant dipole-quadrupole interactions; moreover, in this model, the velocitychanging collision frequency b c is fixed to the theoretical value obtained from the mass diffusion coefficient [13], b diff 0 ¼ 77:2 Â 10 À3 cm À1 atm À1 at 298 K and b diff 0 ¼ 123:7 Â 10 À3 cm À1 atm À1 at 173.4 K. Finally since the results derived from the Rautian profile are only 0.5-0.6% smaller than those derived from the SDRP, we shall only present these latter results, as well as those arising from the Voigt profile. An example of these lineshape fits to the measured profile aðmÞ of the selfbroadened Q Rð9; 4Þ and Q Rð8; 7Þ lines is shown in Fig.…”

“…We have recently measured [13] H 2 -broadening coefficients in the Q R branch of the m 2 band and the P P , R P , and P Q branches of the m 4 band, and the results have been compared to semiclassical calculations. In this work, we extend these measurements for self-broadening and line intensities in the same branches and bands of PH 3 , using a tunable diode-laser spectrometer and two variable absorption pathlength cells.…”

Hydrogen line broadening in the ν2 and ν4 bands of phosphine at low temperature

“…In a recent paper [1] we have measured H 2 -broadening coefficients of PH 3 at room temperature (297 K) in the Q R branch of the m 2 band and the P P, R P, and P Q branches of the m 4 band. Since phosphine is a trace constituent of our atmosphere and has been detected as an important minor constituent in the atmosphere of Jupiter and Saturn [2][3][4][5], measurements of these broadening coefficients at low temperature and determination of their temperature dependence may be very useful.…”

Hydrogen-broadening coefficients in the ν7 band of ethylene at low temperature

“…The results were not satisfactory since the broadening coefficients are significantly underestimated for medium or high J values of the transitions J 0 ; K 0 a J ; K a . Here, we consider another model, recently applied to CH 3 D-H 2 [9] as well as PH 3 -H 2 [10], approximating C 2 H 4 as a linear molecule for its interaction with H 2 and involving the atom-atom Lennard-Jones potential, in addition to electrostatic contributions. It should be noted that this potential describing both long-range and short-range interactions has been successfully used for a number of diatomic and linear molecules perturbed by homopolar molecules such as the N 2 O-N 2 and N 2 O-O 2 systems [11].…”