The Broadening of Spectral Lines by Autoionization, Radiative Transitions, and Collisions.
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
A comprehensive quantum mechanical theory of atomic spectral line shapes is developed within the framework of the Lippmann - Schwinger scattering theory adapted to the tetradic Liouville - space representation of density matrices. An expression for the spontaneous electric-dipole rate is derived which has the same general form as the results obtained by Baranger and by Kolb and Griem for overlapping lines. The frequency-dependent relaxation operator which occurs in this expression involves not only the collisional broadening interaction but also the interactions which give rise to autoionization and to both spontaneous and induced radiative transitions. Explicit expressions for the widths are obtained in the isolated-line approximation by evaluating the lowest-order nonvanishing contribution to the diagonal matrix elements of the relaxation operator. The total width is obtained as the sum of the rates for all inelastic transitions from the initial and final states comprising the spectral line and the term involving the square of the difference between the elastic scattering amplitudes. Finally, we present a qualitative discussion on how the partial widths vary with the states comprising the spectral line and with the physical properties of the surrounding particles and radiation field. Author
- Atomic and Molecular Physics and Spectroscopy
- Quantum Theory and Relativity