Rotational spectra of rare isotopic species of bromofluoromethane: Determination of the equilibrium structure from ab initio calculationsand microwave spectroscopy

• Published in: The Journal of chemical physics 2007-10, Vol.127 (16), p.164302-164302-10
• Main Authors: Puzzarini, Cristina, Cazzoli, Gabriele, Baldacci, Agostino, Baldan, Alessandro, Michauk, Christine, Gauss, Jürgen
• Format: Article
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.2790895

Guided by theoretical predictions, the rotational spectra of the mono- and bideuterated species of bromofluoromethane, C D H Br 79 F , C D H Br 81 F , C D 2 Br 79 F , and C D 2 Br 81 F , have been recorded for the first time. Assignment of a few hundred rotational transitions led to the accurate determination of the ground-state rotational constants, all of the quartic and most of the sextic centrifugal distortion constants, as well as the full bromine quadrupole-coupling tensor for both Br 79 and Br 81 , in good agreement with corresponding theoretical predictions based on high-level coupled-cluster calculations. The rotational spectra of the C 13 containing species C 13 H 2 Br 79 F and C 13 H 2 Br 81 F have been observed in natural abundance and have been assigned, thus allowing the determination of the rotational and centrifugal distortion constants as well as the bromine quadrupole-coupling tensor. Furthermore, empirical equilibrium structures have been obtained within a least-squares fit procedure using the available experimental ground-state rotational constants for various isotopic species. Vibrational effects have been accounted for in the analysis using vibration-rotation interaction constants derived from anharmonic force fields computed at the second-order Møller-Plesset perturbation theory as well as coupled-cluster (CC) levels. The empirical equilibrium geometries obtained in this way agree well with the corresponding theoretical predictions obtained from CC calculations [at the CCSD(T) level] after extrapolation to the complete basis set limit and inclusion of core-valence correlation corrections and relativistic effects.