Studies of C_nBi^- Clusters by Laser Plasma TOF Mass Spectrum

C_nBi^-（n＜ 13） clusters are produced by laser plasma reaction with powder of pure carbon and bismuth. We find that when n value is even, the spectrum peaks are quite high; n value odd, relatively low. This phenomenon, which not similar to Cnn^-clusters, is explained that two electrons on 6s orbit change into lazy ones and can not bond.