Knowledge Bank

Both the absorption and laser Induced emission spectra of the diatomic lead molecule have been examined in argon and neon matrices. The vibronic band systems studied each comprise a considerable number of sharp bands (half widths about 5 $cm-1$), indicating relatively little coupling between the lattice phonons of the host matrix and the vibronic states of the guest $Pb2$ molecule. In the emission studies, very little vibrational relaxation occurs between the laser excitation and the luminescence. We believe we have observed four electronic states not previously reported for this molecule. A comparison of the matrix results with previous gas spectra leads us to the tentative conclusion that the ground state is degenerate and that the degeneracy is removed in the matrix environment. This and other aspects of the spectra of $Pb2$ will be discussed.