Rotational motion compensates the energy defect in near-resonant vibration–vibration energy transfer: A state-to-state study of NO(v)+N2O

Abstract

Our lack of understanding of the factors that compensate energy defects in near resonant V-V energy transfer constrains our ability to accurately predict resonance widths and, thus, the overall importance of such processes. We have carried out one of the first truly state-to-state measurements of near resonant V-V energy transfer under single collision conditions, employing the crossed molecular beams, stimulated emission pumping technique. We have varied the energy defect ⌬E for the process: NO X 2 ⌸(v)ϩN 2 O(0,0,0)→NO X 2 ⌸(vϪ1)ϩN 2 O(0,0,1), by changing the prepared vibrational state from vϭ22 (⌬Eϭϩ14 cm Ϫ1 ) to vϭ21 (⌬EϭϪ18 cm Ϫ1 ) to vϭ20 (⌬EϭϪ49 cm Ϫ1 ). Changes in the energy transfer efficiencies and rotational distributions of vibrationally inelastically scattered NO with energy defect both strongly suggest that molecular rotation ͑both of NO and N 2 O͒ is responsible for compensating the energy defect. Furthermore it appears that relative translation is ineffective in compensating the energy defect. A ⌬J NO ϳ⌬J N 2 0 approximation also appears valid.

Spin−Orbit and Vibrational Relaxation Rate Constants and Radiative Lifetimes for v‘=0−5 Levels of PF(A3Π0,1,2) Molecules

“…The rotational relaxation rates are sufficiently rapid that the initially prepared spin-orbit state attains a thermal rotational distribution before spin-orbit relaxation occurs. 14 Thus, no information about final rotational or Λ-doublet states from the spin-orbit transfer event can be deduced from the present experiments, and the question of formation of high rotational states with minimization of the translational energy defect 15 in the ∆Ω ) -1 or -2 processes cannot be directly answered. On the other hand, the role of the spin-orbit states in the vibrational relaxation mechanism of PF(A 3 Π,V′g1) molecules, ω e ) 436 cm -1 can be investigated.…”

Collisions and Chemistry of Super-Excited Molecules: Experiments Using the PUMP−DUMP−PROBE Technique

“…The PUMP−DUMP−PROBE technique in combination with molecular beams allows us to gain insight into this intriguing question. We studied the specific example using the setup shown in Figure . Here, ( v 1 , v 2 , v 3 ) indicates the number of quanta excited in the symmetric-stretch, bend, and asymmetric-stretch, respectively .…”