Saturation Spectrum of the nu2/nu4 Dyad of AsH3

The nu2/nu4 dyad of arsine, AsH3, has been investigated between 875 and 1100 cm-1 by laser sideband spectroscopy. In total 189 transitions have been observed with sub-Doppler resolution ( approximately 300 kHz) and measured to an absolute accuracy of about 100 kHz. These data may be useful to serve as a secondary frequency standard. Our observations include four perturbation-allowed transitions with Delta(k - l) = 3. Saturation spectra of dipole forbidden transitions had not been previously reported for arsine. Quadrupole hyperfine structure, as well as vibration-rotation splitting of |k - l| = 3N levels in both fundamentals, has been analyzed. Combining our results with MW and RF data (239 frequencies) reported in the literature, a total of 882 transition frequencies were available to fit 15 ground state parameters and 48 excited state parameters of the nu2/nu4 dyad. The standard deviation of the fit is 245 kHz. Copyright 1998 Academic Press. Copyright 1998Academic Press