The Bi2Aln- (n = 1-4) clusters were investigated by anion photoelectron spectroscopy and density functional theory calculations. By photoelectron spectroscopy the vertical detachment energies of Bi2Aln- (n = 1-4) 1-4) were determined to be 2.12 +/- 0.08, 2.32 +/- 0.08, 2.66 +/- 0.08, and 2.15 +/- 0.08 eV, respectively. The structures of Bi2Aln- (n = 1-4) were determined by comparison of photoelectron experiments and calculations. It is found that Bi2Aln- (n = 1-4) anions all have a Bi-2 unit inside their structures, in which the Bi-Bi bond lengths are in the range of 2.81-3.08 angstrom. The natural population analysis shows that the negative charges mainly localized on the Bi2 unit inside the most probable structures. (C) 2014 Elsevier BAT. All rights reserved.