Electron Excitation out of the excited 5P level of Rb using a trapped Rb atom target

賢 海老原

W. Supetitz, B C Duncan, D.I. Lee +1 more

The authors have demonstrated that appropriately time-ordered pulses of diode-laser light can provide efficient population transfer in a three-level cascade system. Laser-trapped Rb atoms are excited from the 5S ground state to the highly-excited 5D level (via the 5P intermediate level) with nearly 100% efficiency. Diode-lasers at 780 nm (5S{yields}5P) and 776 nm (5P{yields}5D) are pulsed with acousto-optic modulators to provide the excitation. The variation of transfer efficiency with relative delay between the two pulses is in good agreement with theoretical expectations. Optimum excitation occurs for the counterintuitive pulse ordering, i.e., when the upper transition is driven first.

Timothy T. Grove, V. Sánchez-Villicaña, B C Duncan +2 more

Michael Søgaard Larsen

Wenko Süptitz, B. C. Duncan, P. L. Gould

We demonstrate that appropriately time-ordered pulses of diode-laser light can provide efficient population transfer in a three-level cascade system. Laser-trapped Rb atoms are excited from the 5S ground state to the highly-excited 5D level (through the 5P intermediate level) with a transfer efficiency approaching 100%. Diode-laser light at 780 nm (5S→5P) and 776 nm (5P→5D) is switched with acousto-optic modulators to provide the excitation. The measured variation of transfer efficiency with relative delay between the two pulses is in reasonable agreement with theoretical predictions. However, the intensities needed for efficient transfer are significantly higher than expected. In general, optimum excitation occurs for the counterintuitive pulse ordering, i.e., when the upper transition is driven first.

P. L. Gould

The authors have used laser cooling and trapping techniques to investigate photoionization and cold collisions. With laser-trapped Rb, they have measured the photoionization cross section from the first excited (5P) level by observing the photoionization-induced loss rate of neutral atoms from the trap. This technique has the advantage that it directly measures the photoionization rate per atom. Knowing the ionizing laser intensity and the excited-state fraction, the measured loss rate gives the absolute cross section. Using this technique, the Rb 5P photoionization cross section at {approximately}400 nm has been determined with an uncertainty of 9%. The authors are currently attempting to extend this method to the 5D level. Using time-ordered pulses of diode-laser light (similar to the STIRAP technique), they have performed very efficient two-photon excitation of trapped Rb atoms to 5D. Finally, they will present results from a recent collaboration which combines measurements form conventional molecular spectroscopy (single photon and double resonance) with photoassociation collisions of ultracold Na atoms to yield a precise ({le}1 ppm) value for the dissociation energy of the X {Sigma}{sub g}{sub +} ground state of the Na{sub 2} molecule.