Pressure broadening, lineshapes, and intensity measurements in the 2 ← 0 band of NO

N2- and O2-Broadenings and Lineshapes of the 551.53-GHz Line of 14NO

“…Such a feature was actually expected since it is now well established that the Voigt profile is approximate even in the millimeter range (26,27). Beside, similar observations were previously reported on the v = 2 ← 0 band of NO (11,15). Indeed, the Voigt profile assumes that the Doppler effect and collision processes are uncorrelated phenomena, whereas they both depend on molecular velocities.…”

“…However, no differential broadening of hyperfine components was observed, and some experiments on the J = 5.5 ← 4.5 line of 15 NO did not highlight any isotopic dependence of pressure broadening parameters. Our experiments are in fair agreement with previously published investigations performed in the infrared range (4,6,(10)(11)(12)(13)(14)(18)(19)(20)(21)(22). They are well explained by semiclassical calculations that use an exact description of collisional partner trajectories (23,24) (Section IV).…”

“…They are well explained by semiclassical calculations that use an exact description of collisional partner trajectories (23,24) (Section IV). On the other hand (Section V), small but significant deviations from the usual Voigt profile have been observed, as previously reported for the infrared domain (11,15). The recorded lineshapes are actually narrowed: they are well fitted by consideration of the speeddependent Galatry profile (25-27), but it was not possible from experimental results alone to discriminate the respective roles of velocity changing collisions and of the dependence of relaxation rates on molecular speeds.…”

“…This result is similar to those previously obtained for CO and O 3 (26,27) and, as discussed, it is well understood by examination of the asymptotic expansion of the polarization correlation function (t) [see Eq. [11] of Ref. (26)].…”

“…To our knowledge, only Pine et al (11,15) have published experimental results dealing with the narrowing of NO lines in the infrared domain. In their work, they consider the sole possibility of velocity changing collisions via the soft collision model of Galatry (43) and the hard collision model of Rautian (48).…”