Stimulated Emission Pumping Spectroscopy of SiH2: First Observation of the Spin–Orbit Interaction between the X̃1A1 and the ã3B1 States

✍ Scribed by Haruki Ishikawa; Yasuhiko Muramoto; Naohiko Mikami

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 203 KB
• Volume: 216
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.2002.8666

✦ Synopsis

Stimulated emission pumping spectra of the à 1 B 1 -X 1 A 1 transition of the SiH 2 radical were observed in order to obtain information about the ã 3 B 1 state through the spin-orbit interaction. The vibrational level structure of the X state, which is the basis for the present observation of the triplet state, was well described with a polyad structure, in which both the 1ν 1 : 2ν 2 Fermi and the 2ν 1 : 2ν 3 Darling-Dennison anharmonic resonances were considered. In the P = 10 polyad, four sets of spin-orbit perturbations were observed for the first time. The triplet state observed at about 9640 cm -1 from the (000) level of the X state was tentatively assigned as the ã 3 B 1 (030) level. An analysis of the spin-orbit interaction showed that the interaction energies of the spin-orbit coupling are 0.73-3.13 cm -1 . This value is rather smaller than that expected based on the comparison with CH 2 . This is considered to be due to poor overlap between the vibrational wave functions in the ã and the X state.