State-Selected Molecular Beam Produced by Laser Manipulation

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The objective of this research is to develop a method that realizes quantum-state selected atomic (molecular) beams. We utilize the atom-guiding technique in which atoms are channeled through a laser-induced dipole-force potential well in a hollow fiber.The outcomes of the two-year project are summarized as follows.(1) We constructed a vacuum chamber consisting of a Cs atomic beam source, a glass capillary mount, and an ion detection system.(2) In order to frequency-stabilize the guiding laser, we developed a novel sub-Doppler spectroscopy that uses a thin vapor cell.(3) Decelerating an incident atomic beam increases the guiding efficiency of the optical potential. As a preliminary experiment, we laser-cooled a Rb atomic beam and reduced its most probable velocity to half of the thermal one.(4) Tow methods were tested in the ionization detection of Cs atoms ; the surface ionization by a Pt hot wire and the laser induced ionization. We found that Cs atoms pumped to the 6PィイD23/2ィエD2 state are ionized by absorbing a single 532-nm photon from a Nd : YAG laser. In our experimental setup, the surface ionization method give much better S/N than the laser-induced ionization method.(5) Laser-guiding experiment was carried out on Cs DィイD22ィエD2 line. The number of Cs atoms ejecting from the capillary increased when the guiding laser was incident. However, this effect can not be attributed to the optical potencial because the guiding efficiency does not depend on the laser frequency.