Forbidden transitions in the emission spectrum of atomic aluminum

Abstract

The emission spectra of species evaporated by a laser pulse from an alumina surface in air have been studied. In addition to the well‐known spectrum of Al, several groups of weak and forbidden lines are identified. The spatial distribution of line intensity and the Stark shifts have been measured. The results are discussed in connection with the plasma shielding effect in laser‐solid coupling and the reduction of aluminum by a high‐temperature method. A weak doublet of lines is tentatively attributed to a transition involving the 3s 3p 2 2 D state.