Product state control through interfering optical ionization routes

Feng Wang, Purdue University

Abstract

In this thesis we report an experimental study of the effect of interference between two two-photon bound-to-free excitation routes in atomic barium from the $\rm 6s\sp2\ \sp1S\sb0$ ground state. Different final products of the transition were observed by monitoring the kinetic energy spectrum of the photoelectrons using a Time-of-Flight electron detector. By tuning the frequency of one of the laser sources used for this work, we were able to change the interference from constructive to destructive, and to demonstrate a strong control over the final product states. Because it only requires two independent tunable laser fields (mutually incoherent), this technique of using quantum interference for product control is very robust. We also studied the dependence of this interference effect and product control on several experimental parameters: the density of the atomic beam, the pulse energy of the lasers, the polarization state of the lasers and the selection of intermediate states. When the density of the atomic beam was increased, we observed that the strength of the interference and the degree of product control increased significantly. When the relative polarization of the two laser fields was changed from parallel to perpendicular, the strength of interference effect increased, but the product control disappeared. In this thesis, we describe the interference, our ability to control product distributions through this interference, and the dependence of interference and product state control on the various experimental parameters.

Degree

Ph.D.

Advisors

Elliott, Purdue University.

Subject Area

Atoms & subatomic particles|Optics

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