Absorption and emission spectra of Li atoms trapped in rare gas matrices

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Abstract
Pulsed‐dye‐laser excitation has been used to investigate the optical absorption and emission spectra of Li atoms trapped in Ar, Kr, and Xe matrices at 10 °K. Attempts to stabilize Li atoms in a Ne matrix at 2 °K were unsuccessful. Results for all three rare gases were qualitatively the same. White light absorption scans showed a single absorption with three peaks centered near the free‐atom 2s→2p transition wavelength. The intensity of fluorescence produced by dye‐laser excitation within this absorption band was measured as a function of emission wavelength. Excitation of the longest‐ and shortest‐wavelength absorption peaks produced identical emission profiles, but no distinct fluorescence signal was detected when the laser was tuned to the central absorption peaks, indicating that the apparent absorption triplet is actually the superposition of a singlet and a doublet absorption originating from two different trapping sites. No additional absorption bands were detected.