Optogalvanic spectroscopy using 389Â nm coherent light source accurately tuned to resonance frequency of 23S->33P of 3He

An efficient 389 nm coherent light source, made possible through the single-pass second-harmonic generation of a picosecond Ti:sapphire laser with a periodically poled lithium niobate waveguide, was developed for the metastability exchange optical pumping of hyperpolarized 3He gas, which is applicable to imaging with nuclear magnetic resonance. The second-harmonic light provided such a broad spectrum that some split sub-levels of its metastable state under an applied magnetic field could be pumped efficiently and simultaneously. Optogalvanic spectroscopy using the light source indicated that the spectral width of 3He was much less than 70 GHz, which was similar to the spectral width of the light source.