Collision self-ionization and self-excitation of a single atom in superbright pumping laser field

Владлен Васильевич Коробкин, M. Iu. Romanovskii

Anne Débarre

Chun-Cheng Tsao, Reginaldo de Jesus Napolitano, Yang Wang +1 more

We report here measurements of two-body photoassociative ionization collisions between sodium atoms within an ultranarrow velocity class selected from a well-collimated, thermal atomic beam. Doppler-shifted excitation of the Na(3s${\mathrm{}}^{2}$${\mathit{S}}_{1/2}$;F=1)\ensuremath{\rightarrow}Na(5p${\mathrm{}}^{2}$${\mathit{P}}_{3/2}$) transition at 285 nm by a single-mode laser defines the narrow velocity class that subsequently populates the F=2 hyperfine level of the Na ground state by optical pumping. Probe laser beam excitation tuned near the Na(3s${\mathrm{}}^{2}$${\mathit{S}}_{1/2}$;F=2)\ensuremath{\rightarrow}Na(3p${\mathrm{}}^{2}$${\mathit{P}}_{3/2}$;F=3) transition produced photoassociative ionization with an average collision energy ${\mathit{E}}_{\mathit{K}}$ corresponding to a temperature of 5.3 mK (${\mathit{E}}_{\mathit{K}}$=3/2kT). We determine the rate constant for the process as a function of probe beam intensity and polarization.

Man Mohan, Vinod Prasad

M Gieler, F. Aumayr, Richard Gaggl +2 more

In atomic collision experiments with laser-excited target atoms it is often desirable to maximize the fraction f* of excited atoms. In the case of Na atoms pumped by a single mode CW dye laser radiation several effects including hyperfine pumping limit f* to about 10%. Using two side-bands of laser radiation, produced by means of an electro-optical modulator (phase modulation of laser radiation by a LiTaO 3 crystal in a microwave field) transitions from both hyperfine ground states of Na can be pumped simultaneously. In this way a significant increase of the fraction of excited Na atoms in the 3 2 P states to typically 30% could be achieved. The advantage of using an electro-optical modulator is demonstrated for the case of state-selective single electron capture studies of the He 2+ -Na*(3p) collision system.

Janusz Czub, Jan Fiutak