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

Reactions of mass-selected Aln− (n=3–23) with O2 produce AlO2−, AlO−, and electron detachment (n≤8); or Aln−4− (n=8–12, 14–22) and sequential dissociation products. All clusters except Al13− 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 Al16− and Al18− retards their oxidation reactions by factors of 2.5±1.0 and 5.0±2.0, respectively. Radiative relaxation of Al16− proceeds with a rate constant of 0.47±0.10 s−1, measured by the return to thermal reaction behavior.