Measurement of lifetime and g factors by level crossing and optical double resonance in the OH and OD free radicals

The zero-field level crossing and optical double-resonance techniques have been used to measure the lifetimes and g factors of several rotational substates in the A2+ excited state of the OH and OD free radicals. Optical excitation was provided by a molecular lamp and individual emission transitions were observed through a monochromator in the beam of resonantly scattered light. The measured g factors are in agreement with the results expected from pure case b coupling for this state. The measured lifetimes are 660 ± 22 and 598 ± 20 nsec for OH and OD, respectively; the mean value 629 ± 22 nsec is suggested. The optical double-resonance experiments allow a tentative lower limit to be placed on the excited-state hyperfine interaction.