Double and Triple Resonance Studies of Rotational Relaxations in NH3-He and NH3-H2 Collisions

Abstract

Collisional relaxation among vibration-rotation levels of NH3 has been extensively studied in relation to an interpretation of the non-thermal stationary state distribution of NH3 in interstellar space [1]. The laser-microwave double resonance method has attained a much higher sensitivity than that of microwave-microwave double resonance, and allows us to study the processes in detail. So far the NH3-NH3 collisions have been investigated in the presence of the pumping at the ν2:Q(J=8, K=7) transition of 14NH3 by the P(13) N2O laser line [2,3,4]. In 14NH3-14NH3 collision the double resonance signal arises from both processes of the collision induced transitions and the resonant energy transfer, while in the mixture of 14NH3 and 15NH3 only the excitation transfer gives rise to the double resonance signal. A well-defined preference rule for collision induced transitions is established and the existence of the efficient V-V excitation transfer process is clarified.KeywordsDouble ResonanceInterstellar SpaceRotational RelaxationInversion TransitionStreng CollisionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.