The microwave spectra of tertiary butyl chloride and tertiary butyl bromide

Abstract

The microwave spectra of tertiary butyl chloride and tertiary butyl bromide were observed in the 8 to 12.4 GHz region using a Stark effect spectrometer with a 100 KHz square wave modulation. The absorption cell was a ten-foot section of S-band wave guide with a flat Stark electrode in the center of the guide and parallel to the broad side. -- All rotational transitions took place at the dry-ice temperature with the ground vibrational state being most dominant. From a partial resolution of the nuclear quadrupole hyperfine structure the rotational constant B₀ and quadrupole coupling constant eQq were calculated for the two dominant species of each molecule. The centrifugal distortion constants were shown to be very small and no attempt was made to evaluate them. -- The rotational constants B₀ and quadrupole coupling constants eQq were obtained for the for species (C¹²H₃)₃C¹²X, where X was Cl³⁵, Cl³⁷, Br⁷⁹, and Br⁸¹. The value eQq = -52.28 ± 1.25 MHz for the case where X was Cl³⁷ is a new result. The remaining constants were found to be in good agreement with the values obtained previously by Lide and Jen, and Ziel, Winnewisser and Huttner. The transitions in this work involved lower J numbers and frequencies than were used previously, that is, the J=1 → 2 and J=2 → 3 transitions.