The lower frequency rQ 2-branch of the torsional split rotational spectrum of H OO H has been recorded for the first time near 1.05 THz with Doppler limited resolution employing a Backward Wave Oscillator as the radiation source. The position of the Q-branch lines can be predicted very closely from a set o f effective rotational constants derived individually for the two torsionally split level...

Z. Naturforsch. 55 a, 481^185 (2000); received February 9, 2000 We have performed an investigation of the internal rotation of the methyl group in trans-cis ethyl vinyl ether by using molecular beam-Fourier transform Microwave (MB-FTMW) spectroscopy. Rotational spectra (up to J = 20) were recorded in the frequency region 4 -19 GHz. Due to the internal rotation of the methyl group, some rotation...

A novel and alternative explanation of the rotational barrier of ethane and several hexasubstituted derivatives, CX3CX3 (X = H, F, CH3, Cl, Br), is suggested based on the evaluation of the properties of the electron distribution. The forces exerted on the electron density of the topological atoms making up a molecule, the Ehrenfest forces, are analyzed and, with the help of the virial theorem, ...

The à A1← X̃ B1 transitions of H2S above the barrier to linearity have been investigated with the energy resolution high enough to identify individual rotational transition lines for the first time. The rotational cooling of the cation is achieved either by the direct ionization or mass-analyzed threshold ionization MATI technique employed in the vacuum-ultraviolet laser excitation of the jet-co...

The rotational barrier around the C-S bond in chlorocarbonylsulphenyl chloride (CIC(O)SCI)is investigated using the INDO, PCILO and GAUSSIAN-70 techniques. The results confirm the existence of planar cis and trans conformers with a higher stability of the latter, as suggested by previous vibrational results. The origin of the rotational barrier is due to an increase of electronic delocalization...

The rotational spectra of the monoterpenoids thymol and carvacrol are reported in the frequency range 2-8.5 GHz, obtained with broadband Fourier-transform microwave spectroscopy. For carvacrol four different conformations were identified in the cold conditions of the molecular jet, whereas only three conformations were observed for thymol. The rotational constants and other molecular parameters...

The crystal structure, rotational barriers and vibrational spectrum of ammonium cyanate have been studied by DFT calculations. The results show that, in the most stable structure, the ammonium ion is oriented such that each N H bond points towards the N atoms of a cyanate anion giving rise to N H N hydrogen bonding, rather than N H O hydrogen bonding. The N C and C O bond lengths suggest that t...

The understanding of the ethane rotation barrier is fundamental for structural theory and the conformational analysis of organic molecules and requires a consistent theoretical model to differentiate the steric and hyperconjugation effects. Due to recently renewed controversies over the barrier's origin, we developed a computational approach to probe the rotation barriers of ethane and its cong...