Laser Control of Product Electronic State: Desorption from Alkali Halides

We demonstrate laser control of the electronic product state distribution of photodesorbed halogen atoms from alkali halide crystals. Our general model of surface exciton desorption dynamics is developed into a simple method for laser control of the relative halogen atom spin orbit laser desorption yield. By tuning the excitation laser photon energy in a narrow region of the absorption threshold, the relative Cl(2P1/2) yield can be made to vary from near 0 to 80% from KCI and from near 0 to 60% for NaCl. We described the physical properties necessary to obtain a high degree of product state control and the limitation induced when these requirements are not met. These results demonstrate that laser control can be applied to solid state surface reactions and provide strong support for surface exciton-based desorption models