Absorption and resonance Raman spectra of Pb2, Pb3, and Pb4 in xenon matrices

Abstract

Lead metal was vaporized and trapped in solid xenon at 12 K. Electronic absorption and resonance Raman spectra were recorded of the resulting matrix, which was shown to contain Pb₂, Pb₃, and possibly Pb₄ molecular species. The vibrational frequency for Pb₂ is determined to be 108 cm⁻¹ for the ground state, with a dissociation energy of ∼8200 cm⁻¹. A D_3h symmetry is suggested for the Pb₃ species, with ν₁=117 and ν₂=96 cm⁻¹. The existence of Pb₄ is suggested by a fundamental and overtone of 111 cm⁻¹ spacing.