A Molecular Beam Laser-Microwave Double-Resonancew Spectrometer for Precise Measurements of High Temperature Molecules

A laser-microwave double-resonance experiment has been developped basing on the principle of the known laser-rf double-resonance technique. This novel beam experiment allows high-resolution measurements of rotational transitions in a molecular ground state. The method was applied to the high-temperature radical CaCl to study the hyperfine structure of transitions between low-lying rotational states. Microwave scans yielded linewidths of 15–20 kHz limited only by time-of-flight broadening and residual Zeeman splitting.