Laser-induced ionizing collisions of ultracold krypton gas in the 1s5 metastable state

Trapping cold ground state argon atoms

We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)  C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)  cm(3) s(-1).

Ion current as a precise measure of the loading rate of a magneto-optical trap

We have demonstrated that the ion current resulting from collisions between metastable krypton atoms in a magneto-optical trap can be used to precisely measure the trap loading rate. We measured both the ion current of the abundant isotope 83Kr (isotopic abundance=11%) and the single-atom counting rate of the rare isotope 85Kr (isotopic abundance∼1×10(-11)), and found the two quantities to be proportional at a precision level of 0.9%. This work results in a significant improvement in using the magneto-optical trap as an analytical tool for noble-gas isotope ratio measurements, and will benefit both atomic physics studies and applications in the earth sciences.

Photoassociation of Ultracold Atoms: A New Spectroscopic Technique

The new spectroscopic technique of photoassociation of ultracold atoms is reviewed, with an emphasis on connecting this area to traditional bound-state molecular spectroscopy. In particular, in contrast to photoassociative spectra at thermal energies, which are broad and of low information content, photoassociative spectra of ultracold atoms are high resolution, permitting observation of small vibrational and rotational spacings of long-range molecular levels near dissociation (typically with outer classical turning points >20 Å). The types of detection and theoretical analysis employed are illustrated, primarily using the example of 39K2. Future directions and applications of this field (e.g., to ultracold molecular formation) are also discussed. Copyright 1999 Academic Press.