Photostimulated desorption and ortho-para conversion of H2 on Ag surfaces.
Photostimulated desorption and change of the ortho-para ratio of H2 physisorbed on Ag at 7 K are reported. After pump laser excitation at 193 nm neutral H2 desorbing in a nonthermal process is state selectively detected by resonance-enhanced multiphoton ionization. At weak pump laser fluence the natural ortho-para conversion of H2 on Ag was monitored to proceed with a conversion time of approximately 780 s, which is in good agreement with predictions based on an electron-exchange-hyperfine-contact model. With increasing pump laser fluence, the ortho-para ratio decreases faster, suggesting photoassisted ortho-para H2 conversion.
Fukutani
K
K
Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan.
Yoshida
K
K
Wilde
M
M
Diño
W A
WA
Matsumoto
M
M
Okano
T
T