High resolution Raman spectroscopy of gases with laser sources. XIII—the pure rotational spectra of 1,3,5,7‐cyclooctatetraene and 1,5‐cyclooctadiene

Abstract

AbstractThe pure rotational Raman spectra of 1,3,5,7‐cyclooctatetraene (C8H8) and 1,5‐cyclooctadiene (C8H12) vapor at pressures of 4 and 2 torr, respectively were photographed under high resolution. The 4765 Å, 4880 Å and 5145 Å radiations of a single mode argon ion laser were used to generate the spectra. The molecular constants found from the analysis of the spectra are, for C8H8: B = 0.090392(15) cm−1, DJ = 1.34(10) × 10−8 cm−1 and, for C8H12: B = ½(A + B) = 0.090345(110) cm−1, DJ = 7.12(1.80) × 10−10, cm−1, where the errors are five standard deviations. These constants are averages over the ground state, the low‐lying vibrational states which are sufficiently populated at room temperature, as well as over the possible conformers concurrently present in the sample.