The Microwave Spectrum of Chloroacetylene and Deuterochloroacetylene

Abstract

The J=1→2 pure rotational transitions in the linear molecules HCCCl35, HCCCl37, DCCCl35, and DCCCl37 have been observed using a Stark modulation microwave spectrograph. The expected quadrupole hyperfine structure has been observed and analyzed in the usual manner, yielding values for the nuclear quadrupole coupling constants of −79.67, −62.75, −79.66, and −63.12 (mc) respectively. The observed Stark effect is in good agreement with that calculated for a linear molecule with a single quadrupolar nucleus using the previously reported value of 0.44 Delsye unit for the dipole moment. The dipole moment calculated from the Stark Effect data is 0.44±0.01 D. Bond distances calculated are H–C=1.052±0.001A, C≡C=1.211±0.001A, and C–Cl=1.632±0.001A.