A Useful Approximation for Fitting Lineshapes in Photoassociation Spectroscopy of Ultracold Atoms
Kevin Jones, Paul S. Julienne, Paul D. Lett, Eite Tiesinga
Lineshapes in photoassociation spectroscopy of ultracold (T<1 mK) atoms are asymmetric and the peak of the line is shifted by a temperature-dependent amount from the zero-temperature threshold. In principle calculating the lineshape requires a full knowledge of both the ground and excited state potentials. We demonstrate here that an approximation based on the Wigner threshold law for scattering yields a relatively simple expression which allows one to extract line positions and linewidths directly from the data. The formula contains a few parameters (threshold frequency, linewidth, temperature, height) and does not require a detailed knowledge of the molecular potentials involved. We illustrate the utility of this approach with examples for Na photoassociation of 500 K and also discuss the limitations of the approach.
Physical Review A (Atomic, Molecular and Optical Physics)
, Julienne, P.
, Lett, P.
and Tiesinga, E.
A Useful Approximation for Fitting Lineshapes in Photoassociation Spectroscopy of Ultracold Atoms, Physical Review A (Atomic, Molecular and Optical Physics)
(Accessed October 24, 2021)