The microwave spectrum of the PCl radical in the <i>X</i> 3Σ− state

Abstract

The microwave spectrum of the P35Cl radical in the ground state has been observed by using a source modulation microwave spectrometer. The PCl radical was produced in a 3.5 m long free space cell by a dc glow discharge in the PCl3 gas. The seven rotational transitions of N=5←4 up to 11←10 were observed in the frequency region of 75 to 169 GHz. The observed spectral lines, 105 in total, were analyzed to give the molecular constants: B0=7558.3464(13), D0=0.006 372 1(45), γ0=−91.525(30), λ0=127 542.92(81), and λD=0.136 76(66), all in MHz with three standard errors in parentheses. The magnetic hyperfine coupling constants have also been determined for both the phosphorus and chlorine nuclei. By comparing these constants with the atomic values the spin density and the s character of the unpaired electron orbital have been calculated to be 87.2% and 0.86% for P and 14.1% and 0.11% for Cl. The Cl nuclear electric quadrupole coupling constant has been determined to be −44.6(15) MHz with the three standard deviation in parentheses.