[3Ca01-12] SS2

[3Ca02] Nuclear spin conversion of polyatomic molecules isolated in rare-gas condensed layers

*Hiroyuki Kawabe¹, Ichiro Arakawa¹, Koichiro Yamakawa² (1. Department of Physics, Gakushuin University, 2. Japan Atomic Energy Agency)

By using infrared absorption spectroscopy, we observed nuclear spin conversion (NSC) of CH₄ and NH₃ isolated in rare-gas condensed layers. All the experiments were performed in an ultrahigh vacuum. In the measurement of CH₄ trapped in Kr layers, we detected NSC from ortho to meta. By analyzing the integrated intensities of these signals as a function of time, we obtained the NSC rate. In the presentation, we will discuss the NSC mechanism of CH₄ and NH₃.