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Theory of Two-Photon Processes

The other important two-photon process is two-photon absorption (TPA), in which two photons are simultaneously absorbed and a molecule is promoted from some state k to a higher-energy state m . The selection rules in TPA are different from those in one-photon absorption, and TPA has proved fruitful in identifying electronic states that are inaccessible to conventional electronic spectroscopy. [Pg.309]

The role implied by these time-ordered graphs for the virtual states called )n should not be taken too literally. In the treatment that follows, these virtual states are in effect expanded in infinite series of true molecular eigenstates n , and no virtual state in any of the processes will coincide with any single, particular true n . Hence, while the energy conservation hcoi + ha 2 = — [Pg.312]

At this point, we have developed our theoretical framework sufficiently to deal explicitly with TPA and Raman spectroscopy. Spontaneous tw6( -photon emission (which is depicted by the last of each set of time-ordered graphs in Figs. [Pg.312]


See other pages where Theory of Two-Photon Processes is mentioned: [Pg.309]    [Pg.309]    [Pg.311]    [Pg.191]   


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