Microwave and submillimeter-wave measurements of (HDCO)-C-12-O-16 in the nu(4), nu(5), and nu(6) bands : Evidence of vibrational induced rotational axis switching ("VIRAS")

• The rotational spectrum of HDCO in the 4(1),5(1), and 6(1) excited vibrational states has been investigated in Lille and Kiel using a sample enriched in deuterium. In Lille, the measurements were performed in the millimeter region (100-600 GHz). The spectra in Kiel were recorded using Fourier transform microwave spectrometers in the regions around 8-18 and 18-20 GHz. employing a rectangular waveguide of length 12 m and a circular waveguide of length 36 m, respectively, These results Acre combined with the 4(1), 5(1), and 6(1) infrared energy levels which were obtained front a previous analysis of FTS spectra of the v(4) (CHD bend), v(5) (CHD rocking). and v(6) bands (out of plane bend) recorded in the 10-mum region at Giessen (A. Perrin, J,-M, Flaud, M. Smirnov, and M. Lock, J. Mol. Spectrosc. 203, 175-187 (2000)). The energy level calculation of the 4(1). 5(1), and 6(1) interacting states accounts for the usual A- and B-type Coriolis resonances in the 5(1) double left right arrow 6(1) and 4(1) double left right arrow 6(1) off diagonals blocks. In addition since the energy levels of the 5(1) and 6(1) states are very strongly resonating, it proved necessary. as ill our previous study. to Use a {J(x), J(z)} nonorthorhombic term in the 5(1) and 6(1) v-diagonal blocks of the Hamiltonian matrix in order to reproduce properly file observed microwave transitions and infrared energy levels. Therefore, this work confirms that HDCO is a good example of the vibrational induced rotational axis switching ("VIRAS") effect.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Deuterium

Electron transitions

Formaldehyde

Fourier transform infrared spectroscopy

Microwave measurement

Submillimeter waves

Physics

Fysik

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