Measurement of absolute state-to-state rate constants for collision-induced transitions between spin-orbit and rotational states of NO(X 2Π, v = 2)

Abstract

Using a pulsed, time resolved IR–UV double resonance technique, we have measured initial and final state specific rates for collision-induced rotational and spin-orbit transitions in NO in its (X 2Π, v = 2) vibronic state. A systematic study of the rates was done for initial and final rotational states with J between 1/2 and 35/2, for both Ω = 1/2 and the Ω = 3/2 spin-orbit components of the X 2Π state. Collision partners were room temperature NO, He, Ar, N2, CO, and SF6. No propensity rules favoring ΔΩ = 0 or ΔJ = 0,±1 were observed, except in NO–He collisions, where ΔΩ = 0 was favored. The state-to-state rates do not vary much with initial state and fall off slowly with increasing ΔJ. Total cross sections for collision-induced rotational transitions were found to be tens of Å2, insensitive to initial state, and correlated with the size of the collision partner.

Multiphoton spectroscopy of NO–Rg (Rg = rare gas) van der Waals systems

“…The latter workers used the observed damping of the diOE raction oscillations in the total diOE erential scattering cross section to determine an eOE ective anisotropy for the interaction potential. Employing laser-induced¯uorescence detection in combination with IR excitation in the ® rst overtone region of NO, Sudbo and Loy were able to measure state-to-stat e relaxation rates [42]. In a pioneering experiment, Joswig and co-workers determined state-resolved integral cross-sections for the NO± Ar system for the ® rst time [43,44].…”

Effects of collisions on electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide

“…For atmospheric-pressure systems, RET rates for NO [12][13][14][15][16] are of the order of 10 10 s −1 . Although incoherent transitions between the groundstate vibrational levels are possible, they are not shown in Fig.…”

“…In the current model, we assume N ␣ eq / N ␣ Ј eq = 0.1. Furthermore, we define a single RET rate parameter R for the unprimed level in all three vibrational manifolds because ground-state [12][13][14] and excited-state 15,16 RET rates agree to within experimental uncertainty. Thus,…”

“…Recent linewidth measurements of infrared 29,30 and microwave 31 transitions confirm the coherence dephasing rate is approximately equal to the RET rate, 12,13 …”

The Cooling Of Internal Degrees Of Freedom Of Polyatomic Molecules in Supersonic Free Jets

“…These two symmetries correspond to different orientations of the electronic cloud compared to the rotational axis. The experimental results show an efficient relaxation of the NO molecule from the 203/2 to the 20 1/2 state in a jet of pure NO [10) while the electronic spin relaxation is uncomplete for jet of NO seeded in Helium (14).…”