15min:

M. NEZU AND T. AMANO, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito 310, Japan; K. KAWAGUCHI, Nobeyama Radio Observatory, Nobeyama, Nagano 384-13, Japan.

The transition dipole moments for the fundamental bands of HNC were obtained from analyses of Herman-Wallis effect on the absorption intensities. All the fundamental bands were measured using a Fourier transform infrared spectrometer(Bruker IFS 120HR) at Nobeyama Radio Observatory. A glow discharge in a mixture of CH₃CN(~ 50 mTorr), H₂(~ 150 mTorr), and Ar(~ 100 mTorr) was used for production of HNC. The spectra were recorded with resolution of 0.01 cm^-1 and the absorption path length was 24 m.

The experimentally determined first order Herman-Wallis coefficients for the ₁ and ₃ bands, combined with the relative value of the transition dipole moments for the ₁ and ₃ bands derived from the relative intensity measurements, yielded the following values for the transition dipole moments (in Debye), using the expressions for Herman-Wallis coefficients given by Watson,

TABLE

These values are considerably larger than the corresponding values for HCN and are in reasonable agreement with ab~ initio values.