Oxidation reactions and photochemistry of aluminum cluster anions (Al3- to Al23-)

Reactions of mass-selected Al-n(-) (n = 3-23) with O-2 produce AlO2-, AlO-, and electron detachment (n less than or equal to 8); or Al-n-4(-) (n = 8-12, 14-22) and sequential dissociation products. All clusters except Al-13(-) absorb at 1064 nm, losing one atom or electron. Several clusters require sequential absorption of two 1064 nm photons to dissociate. Single-photon excitation of Al-16(-) and Al-18(-) retards their oxidation reactions by factors of 2.5 +/- 1.0 and 5.0 +/- 2.0, respectively. Radiative relaxation of Al-16(-) proceeds with a rate constant of 0.47 +/- 0.10 s(-1), measured by the return to thermal reaction behavior. (C) 1998 Elsevier Science B.V.