Matrix Isolation of Pb and Pb2

Abstract

Lead vapor trapped at 20°K in Ar, Kr, Xe, SF₆, and in mixtures of these matrix gases showed an atomic absorption line with no multiplet structure and molecular bands of Pb₂. Warming the matrices above 20°K shifted the atomic line reversibly to the red while the molecular features did not shift. Bulk diffusion of isolated Pb atoms to produce Pb₂ did not take place in Xe even after 2 h at 50°K. However, surface diffusion of Pb atoms to form Pb₂ can take place during the condensation process on a 20°K window under conditions of high heat load or poor thermal contact that cause high surface temperature.