Microwave spectroscopy of nonlinear free radicals III. High field Zeeman effect in HCO and DCO

Abstract

Transitions involving low rotational levels of the HCO and DCO radicals in their ground states have been detected by tuning them to a frequency of about 9 GHz with an external magnetic field. The variation of electric dipole intensity with applied flux density is discussed and the transitions most likely to be detected in a fixed frequency/swept field experiment are characterized. The resonance fields are primarily determined by the size of the spin-rotation interaction. Analysis of the experimental data permits the determination of the dominant component of the spin-rotation tensor, Є_aa, as 11.6176(14) GHz for HCO and 7.1253(17) GHz for DCO. The transition fields are relatively insensitive to the anisotropy of the electron spin g-tensor.