Optical spectra of Yb atoms and dimers in rare gas matrices

Matrix isolated Yb vapor spectra show absorptions due to atoms, dimers, and higher aggregates. The atomic spectrum reveals strong 395 and 344 nm bands and very sharp weaker 267 and 255 nm absorptions in solid argon. The spectrum of Yb2 shows extensive vibrational stucture around 550 nm both in Ar and Kr matrices with a spacing of 48 cm-1. This absorption is assigned to a 6s2(1S0)6s2(1S0)(1Σ+/sub g/) →6s2(1S0)6s6p(1P1)(1Σ+/sub u/) transition similar to the one observed for group IIA metal dimers. Higher aggregate spectra overlap with the 550 nm dimer and weak atomic band