Double-Resonance Lineshapes in a Cell with Wall Coating and Buffer Gas
Svenja A. Knappe, Hugh Robinson
Microwave double resonances were measured is a wall-coated Rb vapor cell as a function of additional buffer gas pressure. These data were compared to similar measurements in an uncoated cell. It was found that the linewidth in the coated cell displays a distinct maximum around 0.2 kPa. This agrees well with theoretical solutions of the diffusion equation assuming a complex reflection coefficient at the wall. It was furthermore found that at the intermediate pressures the lineshapes of the microwave resonances become asymmetric with a low-frequency tail. This is in agreement with the explanation that above the pressure where the alkali mean free path is substantially smaller than the average distance between wall collisions at zero pressure, there exist two classes of atoms in the cell. The atoms that get trapped near the walls accumulate much larger phase shifts compared to the ones toward the center of the cell. This effect is not seen in the longitudinal relaxation rate indicating that it is related to a phase-shift effect.
and Robinson, H.
Double-Resonance Lineshapes in a Cell with Wall Coating and Buffer Gas, New Journal of Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=904448
(Accessed December 10, 2023)