Symmetry Breaking in Two-Photon Dissociation of Pure States

What is required experimentally to achieve this kind of control is the ability to manipulate the phase of the electric field. One possible approach is to use ultrashort i pulses [269, 270] that allow defining the overall electric field phase. Specific applications that are somewhat less experimentally demanding are discussed below. 

To obtain control, we choose the intermediate state Z 3) to be symmetric andfte intermediate state E2) to be antisymmetric, with respect to reflection in the a hypei-plane. Hence we must first demonstrate that it is possible to optically excite, i taneously, both the symmetric i 3) and antisymmetric E2) states from the grouji state i). Using Eq. (3.75) we see that this requires the existence of botj symmetric dipole component, denoted dJ5 and an antisymmetric component, de da, with respect to reflection in the a hyperplane because, by the symmetry ] ties of fs3) and E2), 

We note that the coexistence of symmetric and antisymmetric componenti e dipole moment is with respect to yh. Since the rx plane rotates with the molee ah operation is said to be body-fixed (or molecule-fixed ). Both the body-1 symmetric ds and the body-fixed antisymmetric dfl dipole-moment components occur in A — A electronic transitions whenever the geometry of a bent B molecule deviates considerably from the points on the a hyperplane, characte by the points of equidistance (C2 ) geometries (where du = 0) (see Fig. 8 1S deviation of da from zero on the a plane necessitates going beyond the 1L Condon approximation, which assumes that the electronic dipole moment, dofni change as the molecule vibrates. (In the terminology of the theory df 

Consider first the nature of the d,(y) that enter Eq. (3.79), prior to averaging over scattering angles. We denote this as dq(ij k), where k is the scattering n. Since 3) is symmetric and E2) is antisymmetric, and adopting the 

As a consequence, the net result is that, after angular averaging, Eq. (8.12p becomes 

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SYMMETRY BREAKING IN TWO-PHOTON DISSOCIATION OF PURE STATES 171... 

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