Effect of the Gouy phase on the coherent phase control of chemical reactions
- Department of Chemistry (m/c 111), University of Illinois at Chicago, Chicago, Illinois 60680-7061 (United States)
We show how the spatial phase of a focused laser beam may be used as a tool for controlling the branching ratio of a chemical reaction. Guoy discovered [Acad. Sci., Paris, C. R. 110, 1250 (1890)] that when an electromagnetic wave passes through a focus its phase increases by {pi}. In a coherent control scheme involving the absorption of n photons of frequency {omega}{sub m} and m photons of frequency {omega}{sub n}, the overall phase shift produced by the Gouy phase is (n-m){pi}. At any given point in space, this phase shift is identical for all reaction products. Nevertheless, if the yields for different reaction channels have different intensity dependencies, the Gouy phase produces a net phase lag between the products that varies with the axial coordinate of the laser focus. We obtain here analytical and numerical values of this phase as the laser focus is scanned across the diameter of the molecular beam, taking into account the Rayleigh range and astigmatism of the laser beam and saturation of the transition. We also show that the modulation depth of the interference pattern may be increased by optimizing the relative intensities of the two fields.
- OSTI ID:
- 21024522
- Journal Information:
- Journal of Chemical Physics, Vol. 127, Issue 20; Other Information: DOI: 10.1063/1.2787011; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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