ELECTRONIC ABSORPTION-SPECTRA OF BC, BC-, BC2, AND BC2- IN NEON MATRICES

The electronic absorption spectra of BC, BC2 and their anions were det ected in 5 K neon matrices. After mass-selected co-deposition of BC- w ith excess of neon, an absorption system with origin at 622.7(2) nm is observed and assigned to the A (1)Sigma(+) <-- X (1)Sigma(+) electron ic transition of BC-. Irradiation of the matrix leads to photodetachme nt, and the known B (4)Sigma(-) <-- X (4)Sigma(-) electronic transitio n of BC, as well as a new one C 4 Pi <-- X (4)Sigma(-) with origin at 291.0(2) nm, are observed. Measurements with mass-selected BC2- lead t o the identification of the A (1)Pi <-- X (1)Sigma(+) electronic trans ition of linear BC2- at 432.2(2) nm. Subsequent neutralization leads t o the appearance of two new systems with origin at 851.4(2) and 1587.8 (2) nm of either linear and/or cyclic BC2. In the infrared the nu(1) b and of linear BC2- was observed at 1936.3(1.0) cm(-1) and after irradi ation the nu(2) band of cyclic BC2 at 1196.8(1.0) cm(-1).