Microwave spectrum and quadrupole coupling constant tensor of gauche-isobutyl iodide

Abstract

Microwave spectra of isobutyl iodide have been measured in the frequency region of 10–35 GHz. Only a-type R-branch transitions of one conformer, gauche, were assigned. Three hundred thirty-three quadrupole hyperfine component spectra were measured for the 59 transitions. The rotational constants of the ground vibrational state were determined to be A = 7433.57 ± 0.67 MHz, B = 1088.9006 ± 0.0035 MHz, and C = 991.2657 ± 0.0035 MHz. From the quadrupole hyperfine splittings of the iodine nucleus, the nuclear quadrupole coupling constants in the principal axes system were determined to be χ aa = −1371.1 ± 3.8 MHz, χ bb = 590.8 ± 4.2 MHz, χ cc = 780.3 ± 5.6 MHz, and | χ ab | = 841.7 ± 1.9 MHz.