Triplet-state bound-free transitions of alkali dimers (Na/sub 2/, K/sub 2/, and Rb/sub 2/) by electron-beam excitation

Amplified spontaneous emissions (ASEs) of the Na/sub 2/ violet, K/sub 2/ yellow, and Rb/sub 2/ orange diffuse bands, which are potentially important in the development of continuously tunable high-power laser sources, were observed from electron-beam-excited mixtures of Na-Na/sub 2/, K-K/sub 2/, or Rb-Rb/sub 2/ vapor with argon buffer gas. The continuum spectra centered at 436, 574, and 604 nm were attributed to triplet-triplet Na/sub 2/, K/sub 2/, and Rb/sub 2/ bound-free transitions, respectively. The dissociative recombination reaction of Na/sub 3//sup +/, K/sub 3//sup +/ or Rb/sub 3//sup +/ is discussed as an efficient formation process of the upper states in the present electron beam pumping experiments.