Microwave Spectra and Structure of Ar-1,3-Difluorobenzene


The microwave spectrum of the dimer Ar-1,3-difluorobenzene from 2 to 18 GHz is reported. The spectrum has been observed using a chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer that has recently been expanded to include the 2-6 GHz region of the electromagnetic spectrum. Details of this upgraded spectrometer are reported. Eighty-seven transitions were observed for the parent dimer spectrum, which was adequately fit to a semirigid rotational Hamiltonian consisting of A, B, and C as well as four quartic centrifugal distortion constants. Observations of 13C species in natural abundance were aided by utilizing smaller chirp ranges of 7-9 and 9-11 GHz for 1.9 million and 3.73 million averages, respectively. Assignment of 13C isotopologues allowed for determination of the Kraitchman coordinates of the carbon atoms as well as inertial fits of the complex. The quantum-chemical structure predicts an Ar to monomer center of mass distance of 3.48 Å, compared with 3.564(1) Å determined from experimental structural analysis. This new study indicates that in fluorinated benzene-Ar dimers, when the fluorines are separated by more carbon atoms, the Ar-ring center distance decreases.



Research Center/Lab(s)

Center for High Performance Computing Research

Keywords and Phrases

Carbon; Chemical analysis; Microwave spectroscopy; Quantum chemistry; Spectrometers, Center distance; Center of mass; Centrifugal distortion constants; Chirped pulse; Electromagnetic spectra; Microwave spectrum; Natural abundance; Rotational hamiltonians, Dimers

International Standard Serial Number (ISSN)

1089-5639; 1520-5215

Document Type

Article - Journal

Document Version


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© 2018 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Sep 2018