Knowledge Bank

The transition energy, line width and fine structure of matrix isolated atoms undergo a pronounced reversible temperature dependence change: For copper, silver and gold in rare gases between $20\circ K$ and 0.4 of the solvent melting point, all lines broaden with increasing temperature. The temperature coefficients are not linear, depend on the solvent, and differ for individual sublevels of atomic transitions. Similarly, the coefficients for transition energy shifts vary in a complex way. An attempt is made to correlate the observed effects, and to develop a model which qualitatively explains the observed facts. Our knowledge of neutral atoms-van der Waals solid systems will be compared with that of doped ion crystals.