Mj selectivity in collisional energy transfer between alkali-metal atoms
Abstract
Na atoms in the magnetic field have been selectively excited to each Zeeman sub-level of either the 3p2P1/2 or 3p 2P3/2 state by a tunable dye laser and the Zeeman spectra of the fluorescence from the collisional populated 3p 2P levels have been measured. From the intensities of the Zeeman lines, the selectivity in the collisional transitions between the Zeeman sub-levels of the 3p 2P1/2 and 3p 2P3/2 states has been directly specified. The time evolution of the σ-polarized fluorescence intensity of the Na(3p 2P1/2→ 3s 2S1/2) transition has been measured following the Na(3p 2P3/2â†� 3s 2S1/2) excitation by a σ-polarized short light pulse at H= 129 G. An amplitude modulation was found in the fluorescence from the collisional energy transferred state Na(3p 2P1/2). This is the first observation of quantum beats in collision-induced fluorescence. The frequency of the modulation coincides very well with that of the quantum beats of the resonance fluorescence Na(3p 2P3/2→ 3s 2S1/2), but the phases are opposite. These results are explained by assuming the conservation of coherence during collisional energy transfer.