Activity of chromic oxide catalysts and the chromium valence state

Abstract

Fourier transform infrared spectra of the inversion-rotation transitions have been measured with 0.010-cm−1 resolution between 40 and 300 cm−1 in the ground state and ν2 excited states of 14NH3. Submillimeterwave spectra of the inversion and inversion-rotation transitions in the ν2 state of 14NH3, including a few Δk = ±3 “perturbation-allowed” transitions, have been measured with microwave accuracy between 540 and 770 GHz. A simultaneous least-squares analysis of these data, the microwave ground-state transition frequencies, and the ν2 infrared-microwave two-photon transition frequencies has been carried out. A theory of the Δk = ±3n interactions in the ground and ν2 excited states of ammonia (S. P. Belov, L. I. Gershtein, A. F. Krupnov, A. V. Maslovskij, Š. Urban, V. Špirko, and D. Papoušek, J. Mol. Spectrosc.84, 288–304 (1980)) has been used in the analysis. A set of the ground- and ν2-state molecular parameters has been obtained which describes the experimental data within the precision of the experiment. The “smoothed” values of transition frequencies can be used for calibration purposes with a precision better than 3 × 10−5 cm−1 in the submillimeterwave region, better than 10−3 cm−1 in the far-infrared region, and better than 1.5 × 10−3 cm−1 in the region 700 – 1200 cm−1.