Perturbation of spectral lines by atomic interactions

On quantum-mechanical unified theories of collisional spectral line broadening

“…This difference is most clearly revealed by comparing the integral equations (4) and (8). In the quasistatic and the impact limit the two results become identical.…”

On Argon-Induced Pressure Shifts of198Hg Spectral Lines Associated with Quasi-Rydberg Transitions

“…On the other hand, the knowledge of these effects, in particular the pressure-induced shifts and widths, is significant for fundamental study of interatomic interactions. Veza et al [1] interpreted their results on the basis of the Lindholm-Foley impact theory [4,5] assuming the interaction between Hg and Ar atoms to have the form of a van der Waals or Lennard-Jones potential and found a reasonable agreement with experimental values. They finally concluded, however, that a better representation for the interaction potentials of excited mercury atoms with argon could be potentials which are a superposition of the polarization potential and the Fermi potential.…”

Collision Broadening and Shift of the 535.0 nm Tl Line Accompanying the Photodissociation of Thallium Iodide Perturbed by Noble Gases

“…Their experiment was performed on fluorescence light emitted from a natural thallium vapour mixed with a noble gas at rather high pressure (500-1500 Torr at temperature 743 K). In this pressure range the impact approximation of the line shape theory becomes questionable [5][6][7] and this makes it very difficult the interpretation of the measured values of the half-width and shift of the line. Such a conclusion can be drawn directly from experimental results of Cheron et al [4], who have found that the Lorentzian distribution fits the measured profile in the very close vicinity of the core of the line only.…”