Measurement of the Optical Line Shift and Broadening

Abstract

In this part we consider the shift and broadening of the lines of a working element of the electrodeless discharge spectral source. For ignition of the discharge and intensity stabilization of the working element, buffer gas (mainly Kr) is usually used in the spectral lamps. Therefore the emitted radiation results from optical transitions of the studied atoms placed in a foreign gas medium. Atoms of the foreign gas perturb the energy levels of the working element atoms, resulting in a shift and broadening of the emission and absorption lines. Therefore, for an exact description of the spectral distribution of the emission of a spectral lamp it is necessary to know the spectral line shifts and broadenings, determined by collisions with the noble gas atoms. When detailed studies of the spectral light sources first began there was no reliable information available concerning pressure effects on the spectral characteristics of lamps and absorbing cells. In this connection the method of magnetic scanning was investigated and developed. This method yielded reliable information on the factors pertaining to shifts and broadening of lines for a number of elements. In spite of some pioneering work on the application of the magnetic scanning principle for investigating the spectra of colliding atoms, since 1965 systematic developments of the magnetic scanning method and its applications to study of the collision broadenings and shifts of spectral lines of atoms have been carried out independently by two groups, in Paris (Department of Physics, Université Pierre et Marie Curie) and Leningrad (Coherent Optics Laboratory, Leningrad State University).