PHOTOPHYSICAL AND ELECTRON-ATTACHMENT PROPERTIES OF ARF-EXCIMER-LASERIRRADIATED H-2

Detailed electron attachment and spectroscopic measurements are report ed on ArF-excimer-laser irradiated H-2. These studies indicate that pr eviously reported efficient H- formation in ArF-laser irradiated H-2 i s due to electron attachment to high-lying Rydberg (HR) states indirec tly populated by the laser irradiation. Electron attachment studies in dicate a lifetime of greater than or equal to 40 ns for the electron a ttaching state(s): The spectroscopic studies show that vacuum ultravio let emission due to the B (1) Sigma(u)(+) --> X (1) Sigma(g)(+) transi tions continues for up to similar to 100 ns after the termination of t he laser pulse and thus that the B state is populated by cascades from higher-lying states with longer lifetimes. The temporal profile of Ly man-alpha emission due to the H(n = 2) to H(n = 1) transitions is cons istent with the production of H(n = 2) states by electron attachment t o HR states.