Dynamics of the CO2 lower laser levels as measured with a tunable diode laser

Spectroscopy and energetics of the acetylene molecule: dynamical complexity alongside structural simplicity

“…The effective transition matrix element hinitjV eff jfinali for intra-dyad V-V transfer is then predominated by the difference between matrix elements hð0 2 0 0Þ 0 þ jV eff jð0 2 0 0 0 Þ 0 þ i and hð1 0 0 0Þ 0 þ jV eff jð1 0 0 0Þ 0 þ i that are diagonal in the Class A basis-states [58,59,360]. Estimates of such vibrational basis-state matrix elements indicate that they cancel to less than 0.1% [58,59,360,366,367]; this is consistent with the low efficiency of J-resolved V-V transfer kinetics within the 1 337-cm À1 ( 1 /2 2 ) Fermi dyad of CO 2 , as measured in IR-IR double-resonance experiments [58,59,360,368], but contrary to earlier interpretations apparently guided by intuitive expectations that strong Fermi resonance (or other forms of intramolecular coupling) would necessarily enhance V-V transfer.…”

Theory of saturated-absorption cavity ring-down: radiocarbon dioxide detection, a case study

“…Moreover, the decay rate of the 00 0 1-excited 12 C 16 O 2 molecules is relatively low, in the order of thousands of s −1 at 12 mbar [34,35], because they exchange the vibrational energy mainly between themselves. This relatively slow single exponential [35] decay, compared with the estimated γ ∥ value, means that, for 14 C 16 O 2 molecules, relaxation of vibrational energy to translation motion or to different vibrational manifolds of 14 C 16 O 2 is negligible with respect to quenching events of type (3). For the same reason, we also note that the saturation intensity for similar ro-vibrational transitions of 12 C 16 O 2 molecules would be much lower than for 14 C 16 O 2 .…”

“…(A11) is twice the value given by Eq. (35) in the homogeneous regime where w G ≪ w L . Here we consider the opposite situation, where a given velocity group which is resonant with one of the two counterpropagating waves is generally far from resonance with the other wave.…”

On the quality of MIPAS kinetic temperature in the middle atmosphere

“…A new V-V v 2 collisional scheme has been included, in which we have used the values of Dang et al (1983) for the V-V exchange between the three v 2 = 2 levels and the v 2 = 1 level, and have scaled these values using the harmonic oscillator law and an energy gap law for collisions in which more energetic levels or different isotopes take part. In particular, for the 020 triad and for inter-isotopic V-V exchange, that results in a two times faster net exchange rate of ν 2 quanta in CO 2 -CO 2 V-V collisions (k vv ) than that used in López-Puertas and Taylor (2001).…”

“…The atomic oxygen used in the retrievals is taken from MSIS (Picone et al, 2002), for which we have assumed an uncertainty of 50 % also based on considerations in García-Comas et al (2008). The value for k vv used in v511, v611 and v711 is that measured by Dang et al (1983) and we have assumed their error measurement uncertainty (20 %). Overall, the typical non-LTE systematic error is smaller than ±0.1 K below 70 km, ±1.4 K at 85 km, ±6 K at 95 km and ±11 K at 100 km.…”