Photoionization cross-sections of the first excited states of sodium and lithium in a magneto-optical trap

A two element magneto-optical trap (MOT) for Na and ⁷Li or ⁶Li is used to cool and trap each of them separately. A fraction of the cold atoms is maintained in the first ²P_3/2 excited state by the cooling laser. These excited state atoms are ionized by laser light in the near-UV region, giving rise to a smaller number of trapped atoms and to different loading parameters. Photoionization cross-sections were derived out of these data. They are in reasonable agreement with data previously obtained using thermal samples and with theoretical predictions. Received 21 March 2001 and Received in final form 3 August 2001     

Radiative lifetimes of 7d, 8d <Superscript>1</Superscript>D<Subscript>2</Subscript> excited states of Hg I

Radiative lifetimes of 7d, 8d ¹ D ₂ excited states of Hg I are measured using pulsed two-photon excitation from the ground [Xe]5d ¹⁰6s ^{2 1} S ₀ mercury state, detecting the decay of the laser-induced fluorescence. The results are compared with theoretical values, obtained by means of a Hartree-Fock single configuration method, taking into account electron configuration interaction. The radiative lifetime value dependence on the effective principal quantum number for the nd ¹ D ₂ series is analyzed and compared with the quantum defect dependence. Received 25 February 2000 and Received in final form 26 July 2000     

Investigation of the hyperfine structure of Ta I lines (V)

We report on further investigations of the hyperfine structure of spectral lines of the neutral tantalum atom. Besides determination of the hyperfine constants A and B of 21 levels we report on the discovery of 9 up to now unknown fine structure levels for which we could determine their energy position, parity, angular momentum and the constants A and B. For a large number of up to now unclassified lines the combinations could be identified. Received 27 June 2000 and Received in final form 23 August 2000     

Nonlinear emission in sodium vapour upon pulsed-laser excitation of the 42 P levels

Parametric four-wave mixing, stimulated electronic Raman scattering and amplified spontaneous emission cascades have been studied experimentally by single-photon resonant and near-resonant excitation of the 4² P levels of dense sodium vapour. The dependence of emission intensities on laser detuning and exciting laser power is discussed.     

The sodium D2-line in electric and magnetic fields. Part III: adiabatic hyperfine level transfer in perpendicularly crossed fields

Numerical calculations of the splitting of the hyperfine statesM _F of an atom influenced by crossed electric and magnetic fields were performed. These calculations show that, adiabatically changing the presence and the strength of the fields according to a well defined cycle, atoms populated in a given hyperfine levelF _i before the start of the field cycle may be found in another levelF _f after experiencing the field cycle.     

A high-precision measurement of the stark shift of the sodium D1-line

Using laser—atomic-beam spectroscopy and a special field arrangement the Stark shift of the sodium D₁-line was determined to be 48.986 (112) kHz (kV/cm)^?2. Using the literature value for the scalar polarizability of $\text{2}{}^2\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, 39.7 (8) kHz (kV/cm)^?2, the polarizability of $\text{2}{}^2\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was derived to be 88.69 (81) kHz (kV/cm)^?2.     

Cross-section for collisions of ultracold Li with Na

In a magneto-optical trap (MOT) we are able to simultaneously trap and cool ⁷Li and Na. We investigated the loading behavior of the cloud of Li atoms in presence of the overlapped cloud of cold Na atoms, and, by blocking the weak repumping beam for Na, compared it with the loading curve for Li atoms only. Out of these loading curves we calculated the collision cross-section of Na on Li to be 10^-11 cm ³ /s. Received 11 January 2002 / Received in final form 5 April 2002 Published online 24 September 2002