IONIZATION OF ALKALI-METAL RYDBERG ATOMS BY BLACKBODY RADIATION

Results of theoretical calculations of ionization rates of Rb and Na Rydberg atoms by blackbody radiation are presented. Calculations have been performed for nS, nP and nD states of Na and Rb, which are commonly used in a variety of experiments, at principal quantum numbers n =8 . 65 and at three ambient temperatures of 77, 300 and 600 K. In the calculations we have taken into account the contributions of BBR-induced redistribution of population between Rydberg states prior to photoionization and .eld ionization by extraction electric .eld pulses.

Figure 1: A comparison of the calculated BBR photoionization rates of Na nD Rydberg atoms with the experimental data.

A semi-classical model [1] was used to calculate the bound-bound and bound-free matrix elements. The obtained results show that these phenomena affect both the magnitude of total ionization rates and shapes of their dependencies on the principal quantum number n. The theoretical ionization rates are compared with the results of our earlier measurements of BBR-induced ionization rates of Na nS and nD Rydberg states with n = 8 - 20 at 300 K [2], and good agreement for all states except nS with n > 15 is obtained. Useful analytical formulae allowing quick estimates of ionization rates are also presented [3].

References

[1]L.G.Dyachkov and P.M.Pankratov, J. Phys. B 27, 461 (1994).

[2]I.I.Ryabtsev, D.B.Tretyakov, I.I.Beterov, N.N.Bezuglov, K.Miculis and A.Ekers 2005 J. Phys. B 38, S17 (2005).

[3]I.I.Beterov, D.B.Tretyakov, I.I.Ryabtsev, A.Ekers, and N.N.Bezuglov, Phys. Rev. A 75, 052720 (2007).

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Research activities

• Introduction
• Establishment of the Molecular Beam Laboratory and Laser Centre
• Population transfer to high-lying molecular levels.
• Lifetime and branching ratio measurements using the Autler-Townes effect
• Stochastic phenomena in collisions with Rydberg atoms.
• Stochastic behaviour of photons in absorbing media and its applications.
• Spectroscopic manifestation of radiation trapping in a supersonic beam.
• Ionization of Alkali-Metal Rydberg atoms by blackbody radiation.
• Manipulation of spatial distribution of excited molecules in a beam via dressed-state interference.
• Metastable Rydberg states and blocade effect.
• Stark switching of microwave field induced dynamic chaos regime.
• Line broadening due to optical pumping at unsaturated fields in atomic and molecular beams.
• Lifetime studies of alkali nf-levels.
• Conditions and limitations for resolution of hyperfine structure in the Autler-Townes spectra.
• Fluorescence decay at subnatural times in a magneto optical trap.
• Reconsideration of spectral line profiles affected by transit time broadening
  
• Population switching via interferences in the Autler-Townes effect
• Penning ionization of cold Rb Rydberg atoms due to long-range dipole-dipole interaction