Photoionization cross section measurement in a Rb vapor cell trap

Near threshold photoionization of excited alkali atoms Ak(np) (Ak = Na, K, Rb, Cs; n = 3-6)

“…The influence of core polarization is most pronounced for K(4p) and attributed to the collapse of the d-orbital towards smaller distances which starts to occur for atomic number Z = 19 [35] and thereby produces a large sensitivity to comparatively small interactions. The theoretical results are compared with available experimental data, including recent results for cold Rb(5p 3/2 ) [37][38][39] and Cs(6p 3/2 ) atoms [50] in a magneto-optical trap and laserexcited, polarized K(4p 3/2 ) atoms in a collimated atomic beam [14].…”

“…In Figure 7A we compare theoretical photoionization cross-sections for unpolarized Rb(5p 3/2 ) atoms with available experimental data [36][37][38]. The effect of core polarization is seen to raise the cross-section near threshold by about a factor 1.77 relative to the CIPF results.…”

“…Their cross-section 9.6(20) Mb (1σ uncertainty) is somewhat low in comparison with the CIPFCP and CFCP results. More recently, three measurements have been carried out on photoionization of cold, trapped Rb(5p 3/2 ) atoms [37][38][39]. In a pioneering experiment, Gould's group [37] demonstrated the virtue of using cold atoms in a magneto-optical trap for quantitative photoionization studies.…”

“…We note that this experiment deals with an effectively unpolarized sample of excited atoms Rb(5p 3/2 ) atoms due to spatially varying polarizations of the trapping laser beams across the photoionization volume [40]; no variation of the angular-resolved fluorescence from the trapped atoms was observed when a linear polarizer was rotated in front of the fluorescence detector [40]. In another experiment on trapped Rb atoms, Gabbanini et al [38] measured a photoionization cross-section of 14.8 (22) Mb close to threshold (ε = 0.04 eV) from the change of the filling rate of a magneto-optical trap with and without a photoionizing Ar ion laser (476.5 nm). This value is in good agreement with the CIPFCP and CFCP results.…”

Optimization of the current extracted from an ultracold ion source

“…where σ PI = 1.48 × 10 −17 cm 2 is the photo-ionization cross section for 85 Rb [19], the ionization laser beam is focused to an area A i = 2πσ 2 i , h is Planck's constant and c is the speed of light. The quantity τ i is the typical time it takes for an atom to be ionized.…”