Strong collision model for light-induced drift of multi-level atoms

Analytical expressions describing the light-induced drift (LID) of alkali metal vapours reasonably well both under conditions of ground state optical hyperfine pumping and in its absence are obtained. It is shown that under the conditions of optical pumping the LID effect of the particles arises under the action of its own fluorescent radiation. The drift velocity for sodium atoms in a argon atmosphere reaches a value of 1 cm s-1 for fluorescent radiation of intensity 20 mW cm-2.

Section: (34)mentioning

confidence: 73%

Light-induced drift under conditions of ground state optical hyperfine pumping

Atutov¹,

Пархоменко²,

Pod'yachev³

et al. 1992

“…The strong collision model has been found to be a very good approximation, and the resulting strong collision cross sections relate directly to the diffusion coefficients for the atomic levels (Haverkort et al 1988). The strong collision model used here is described by Streater and Woerdman (1989). The calculation provides the drift velocities if the laser and atomic parameters are known.…”

Section: Results and Analysismentioning

confidence: 99%

Diffusion cross sections for potassium and levels in rare gases

Yahyaei-Moayyed¹,

Hickman²,

Streater³

1996

Self Cite

We have used a light-induced drift (LID) experiment to determine ratios of cross sections for diffusion of potassium in the excited 4 2 P 3/2 , 4 2 P 1/2 and the ground 4 2 S 1/2 levels in five rare gases. The measured ratios are combined with the ground-state cross sections and statistically averaged excited cross sections, available from a previously reported light induced diffusive pulling experiment, to obtain the absolute cross sections for individual fine structure levels. We also report calculated cross sections based on available potential curves and a coupled-channel theory. Rough qualitative agreement is generally found between the absolute cross sections inferred from experiment and the theoretical values. The light-induced drift experiments, however, measure ratios of cross section differences that are highly sensitive to the potential curves. It is found that the available potential curves are not adequate for predicting these measured ratios.

“…By measuring the drift velocities for the D, and D, line excitations under identical conditions, the ratio Vd(J = f): Vd(J = a) can be measured. The ratio A u ( J = $ ) : A u ( J = 4) can then be found using a four-level strong collision model (Streater and Woerdman 1989). The cross sections in the model are constrained to give the mixed value (through equation ( 23)) measured by the diffusive pulling experiment and reported in table 1.…”

Section: O ( ~~S )mentioning

confidence: 99%

Momentum transport cross sections for excited and ground state potassium with rare gases by light-induced diffusive pulling

Mugglin¹,

Streater²

1993

Self Cite

We have used the light-induced diffusive pulling (LDP) method to measure the ground state momentum transport cross sections and the relative difference of the excited and ground state cross sections with respect to the ground state for potassium with several inert gas atoms. For the LDP measurements, the excited state cross section is a weighted average of the potassium 4'P,/, and 4'P,/, fine structure levels, which are mixed by collisions with the inert gas atoms. We have also used a light-induced drift (LID) experiment to measure the ratio of the differences in the excited and ground state cross sections for the individual fine stmcture levels (Au(3 = 5) : A u ( J = 1)) for potassium-Ne and patassium-Ar. For the case of potassium-Ar, we have combined this ratio with the results from the LDP measurements to obtain absolute transport cross sections for the individual 4'S,/,, 4'P,,, and 42P3/2 levels.