Influence of the interaction potential shape on the Dicke narrowed spectral line profiles affected by speed-dependent collisional broadening and shifting

Variations of the Dicke narrowed spectral line profiles caused by change of the interaction potential shape are investigated. We propose line shape model, which incorporates the speed-dependent collisional broadening and shifting as well as the velocity-changing collisions, described by the class of r−ν-type repulsive potentials. Following Blackmore (1987) [55], calculations were carried out using the Liouville formalism. In contrast to previous analysis, we concluded that the pure Dicke narrowed profiles calculated for various potential types can differ by almost 20%. Assuming the same speed dependence of collisional broadening and changing the type of interaction potential responsible for velocity-changing collisions the subpercent variations of calculated line shapes were observed. It was shown that in the case when these both contributions, the collisional broadening and the velocity-changing collisions, are related to the r−ν-type interaction potential the variations of calculated line shapes are more than one order of magnitude bigger than in previous case and are dominated by speed-dependent collisional broadening. In the case of supersensitive spectroscopy, where accuracy of the line shapes measurements approaches 10−6, the accuracy of the retrieved line shape parameters can be strongly affected by the assumed type of interaction potential related to velocity-changing collisions.

► Influence of collisional potential shape on the spectral profiles was investigated. ► Variations of velocity-changing (VC) collisions with the potential were included. ► Profile variation is dominated by contribution related to dephasing collisions. ► Potential impact on VC contribution can not be ignored for high SNR data. ► Profile variation can be as high as 20% for pure VC contribution to collisions.