UV ABSORPTION OF LIO IN A SUPERSONIC JET

We report the first observation of electronic spectra of a lithium oxi de in a supersonic jet. Using laser ablation of lithium in the presenc e of N2O, a new laser-induced fluorescence excitation spectrum in the 325-355 nm region has been observed. We tentatively assign this spectr um to the C-2 Pi-X-2 Pi transition of LiO. When N2O is added downstrea m of the nozzle instead of bring seeded into the inert carrier gas, th e 325-355 nm excitation spectrum disappears and a new excitation spect rum is seen much further to the red. From these findings we deduce tha t the exothermic reaction Li + N2O --> LiO + N-2 produces a population inversion in the LiO product, most likely an electronic state populat ion inversion. (C) 1998 Elsevier Science B.V.