Influence of atom-surface collisional processes in FM selective reflection spectroscopy

Anne Amy‐Klein, O. A. Rabi, Solomon M. Saltiel +6 more

We report on recent developments in selective reflection spectroscopy at a vapor interface. In FM linear spectroscopy, the long range van der Waals surface interaction, responsible for lineshapes distortions and shifts, is quantitatively well understood with respect to the nature of the dielectric surface. Pump‐probe saturation effects in reflection spectroscopy on a two‐level system offer alternate ways of probing surface interaction, while nonlinear reflection spectrsocopy on a three‐level cascade system provides a unique tool for probing in a vapor cell the velocity distribution of desorbing atoms.

Jingzhong Guo, J. Cooper, Alan C. Gallagher +1 more

Jingzhong Guo, J. Cooper, Alan C. Gallagher +1 more

J. Lukusa Mudiayi, T. Mashimo, Isabelle Maurin +3 more

Selective reflection spectroscopy at normal incidence provides signals with sub-Doppler resolution, linear with optical intensity. Frequency modulated (FM) selective reflection probes atomic vapours at distances comparable to the excitation wavelength (~λ/2π) and is used extensively to probe the Casimir-Polder interactions between an excited state atom and a macroscopic surface. Extending selective reflection spectroscopy to molecular gases allows probing a thin layer of molecular gas next to a surface. This is a very attractive prospect that allows envisaging high-resolution molecular spectroscopy and molecular frequency references in a compact and miniaturised apparatus, such as a thin cell [1] or a photonic crystal [2]. Additionally, it paves the way for spectroscopic probing of the Casimir-Polder interaction with molecules. The molecule-surface interaction has been the object of extensive theoretical investigations, focusing on the effects of molecular orientation and chirality. However, experimental tests are few and comparison with theoretical predictions has been challenging [3].

P. Chaves de Souza Segundo, I. Hamdi, M. Fichet +2 more

We report on the analysis of FM selective reflection experiments on the 6S1/2->8P3/2 transition of Cs at 388 nm, and on the measurement of the surface van der Waals interaction exerted by a sapphire interface on Cs(8P3/2). Various improvements in the systematic fitting of the experiments have permitted to supersede the major difficulty of a severe overlap of the hyperfine components, originating on the one hand in a relatively small natural structure, and on the other hand on a large pressure broadening imposed by the high atomic density needed for the observation of selective reflection on a weak transition. The strength of the van der Waals surface interaction is evaluated to be 73±10 kHz.µm3. An evaluation of the pressure shift of the transition is also provided as a by-product of the measurement. We finally discuss the significance of an apparent disagreement between the experimental measurement of the surface interaction, and the theoretical value calculated for an electromagnetic vacuum at a null temperature. The possible influence of the thermal excitation of the surface is evoked, because, the dominant contributions to the vW interaction for Cs(8P3/2) lie in the far infrared range.

N. Andersen