Lowest Overtone and Combination Levels of DCCI: The Fermi Resonance v3 = 1/v5 = 2.
The infrared spectrum of deuterated monoiodoacetylene DCCI in the region of 220-550 cm-1 has been studied at a resolution of 0.0020 cm-1. The hot bands nu3 <-- nu15 and 2nu0,25 <-- nu15 have been analyzed by considering especially the Fermi resonance v3 = 1/v5 = 2. In the next layer of the hot bands (nu3 + nu5)1 <-- nu3, (nu3 + nu5)1 <-- 2nu0,25 and 3nu1,35 <-- 2nu25 the same Fermi resonance appears between v3 = v5 = 1 and v5 = 3. In addition, various l resonances at the overtone levels have been considered. As a result, the vibrational and rotational constants for the level systems v3 = 1/v5 = 2 and v3 = v5 = 1/v5 = 3 together with the resonance parameters have been obtained. Copyright 1999 Academic Press.
Rotational dependence of Fermi resonance in linear molecules
Abstract Formulas in terms of basic molecular parameters are presented for the constants δ stt ′ and δ ′ stt ′ that describe the rotational dependence of the Fermi interaction between a stretching fundamental ω s and an overtone 2 ω t ( t = t ′) or a combination ω t + ω t ′ of bending modes of a linear molecule. Numerical comparisons are made with existing calculated or observed values of δ 122 and δ ′ 122 for several linear triatomic molecules.
Microwave Fourier‐transform spectrometer for the entire K band for the investigation of rotational spectra of molecules in the gas phase
We present the experimental set up of a microwave Fourier‐transform spectrometer for the entire K band from 18 to 26.4 GHz. It is hereby shown that this type of spectroscopy is achieved above 18 GHz. Advantages and disadvantages are discussed. The performance is illustrated by the recordings of rotational transitions of various molecules.