15min:

N. SHIMIZU, R. FUJIMORI, J. TANG, K. KAWAGUCHI, Department of Chemistry, Faculty of Science, Okayama University, 3-1-1, Tsushima-Naka, Okayama 700-8530, Japan; T. ISHIWATA, Graduate School of Information Sciences, Hiroshima City University, 3-4-1 Otsuka-Higashi, Hiroshima 731-3194, Japan,.

In 1987, Friedl and Sander reported observation of the FTIR spectrum of the ₂ band of ¹⁴NO₃ in 762 cm^-1 region, and rotational analysis was carried out for only transitions with K=3. The obtained negative centrifugal distortion constant D_N implied presence of perturbation from other states, but the perturbation analysis has not been carried out. In the present study, the ₂ band of \textrm¹⁵NO₃ was first observed in 742 cm^-1 region. In contrast to the case of ¹⁴NO₃ , rotational assignments were carried out for K=0, 3, 6, 9, 12, and 15, and transitions with N\leq12 were fitted with usual energy level expression for D_3h molecule. However, when we included higher N transitions up to N=22, an effect of Coriolis interaction from v₄=2 appeared in negative D_N for K=0 and staggering in K=3. An energy matrix including \ell=0 and \ell=\pm2 of v₄=2 and \ell=0 of v₂ =1 was used to obtain the energy values of v₂ =1 , including the Corilis and \ell-type resonance terms. From the determined interaction constant between v₂ =1 and v₄=2 , anharmonic constant k₄₄₄ was estimated, by assuming a mixing of v₄=1 and v₄=2.