Rapid capture of large amplitude motions in 2,6-difluorophenol: High-resolution fast-passage FT-MW technique

• Published in: Journal of molecular spectroscopy 2012-10, Vol.280, p.54-60
• Main Authors: Jahn, Michaela K., Dewald, David A., Wachsmuth, Dennis, Grabow, Jens-Uwe, Mehrotra, Suresh C.
• Format: Article
• Language: English
• Subjects: Broadband fast-passage spectrometer; Internal rotation; Large amplitude motions; Microwave spectroscopy; Rotational spectrum; Supersonic jet
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/j.jms.2012.07.006

[Display omitted] ► A new design of broadband IMPACT-FT-MW spectrometer is briefly presented. ► Linewidth in order of the COBRA-FT-MW experiment can be reached. ► Spectroscopic constants of 2,6-difluorophenol are determined. ► Tunneling splitting and the Coriolis coupling constant are studied. The rotational supersonic-jet Fourier transform microwave (FT-MW) spectra of the aromatic 2,6-difluorophenol (DFP) have been recorded and analyzed in the frequency range of 8–26GHz. A new design of broadband FT-MW spectroscopy with in-phase/quadrature-phase-modulation passage-acquired-coherence technique (IMPACT) has been used to obtain the spectra rapidly at high-resolution, obsoleting subsequent measurements with a resonator spectrometer. The structural analysis shows that the H-atom of the hydroxyl-group is located in the benzene plane forming an intramolecular hydrogen bond with one of the F-atoms. Due to the tunneling motion of this H-atom between two the equivalent positions, a large part of the rotational transitions are split into two signals being separated by ∼17MHz. The rotational constants, centrifugal distortion constants and the Coriolis coupling constant have been determined.