Rotational constants and structure of para-difluorobenzene determined by femtosecond Raman coherence spectroscopy: A new transient type

Den, Sebastian Takuya; Frey, Hans-Martin; Felker, Peter M.; Leutwyler, Samuel (2015). Rotational constants and structure of para-difluorobenzene determined by femtosecond Raman coherence spectroscopy: A new transient type. The Journal of Chemical Physics, 143(14), pp. 144306-1. American Institute of Physics 10.1063/1.4932602

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Femtosecond Raman rotational coherence spectroscopy (RCS) detected by degenerate four-wave mixing is a background-free method that allows to determine accurate gas-phase rotational constants of non-polar molecules. Raman RCS has so far mostly been applied to the regular coherence patterns of symmetric-top molecules, while its application to nonpolar asymmetric tops has been hampered by the large number of RCS transient types, the resulting variability of the RCS patterns, and the 10³–10⁴ times larger computational effort to simulate and fit rotational Raman RCS transients. We present the rotational Raman RCS spectra of the nonpolar asymmetric top 1,4-difluorobenzene (para-difluorobenzene, p-DFB) measured in a pulsed Ar supersonic jet and in a gas cell over delay times up to ~2.5 ns. p-DFB exhibits rotational Raman transitions with ΔJ = 0, 1, 2 and ΔK = 0, 2, leading to the observation of J −, K −, A −, and C–type transients, as well as a novel transient (S–type) that has not been characterized so far. The jet and gas cell RCS measurements were fully analyzed and yield the ground-state (v = 0) rotational constants Aₒ = 5637.68(20) MHz, Bₒ = 1428.23(37) MHz, and Cₒ = 1138.90(48) MHz (1σ uncertainties). Combining the Aₒ, Bₒ, and Cₒ constants with coupled-cluster with single-, double- and perturbatively corrected triple-excitation calculations using large basis sets allows to determine the semi-experimental equilibrium bond lengths rₑ(C₁–C₂) = 1.3849(4) Å, rₑ(C₂–C³) = 1.3917(4) Å, rₑ(C–F) = 1.3422(3) Å, and rₑ(C₂–H₂) = 1.0791(5) Å.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Applied Physics
08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Den, Sebastian Takuya; Frey, Hans-Martin and Leutwyler, Samuel

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
600 Technology > 620 Engineering
500 Science

ISSN:

0021-9606

Publisher:

American Institute of Physics

Language:

English

Submitter:

Beatrice Niederhauser

Date Deposited:

02 Feb 2016 16:08

Last Modified:

10 Feb 2016 06:31

Publisher DOI:

10.1063/1.4932602

BORIS DOI:

10.7892/boris.75046

URI:

https://boris.unibe.ch/id/eprint/75046

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