One-Photon Dissociation with Laser Pulses

Assuming that the field is in near resonance or on resonance with transitions from the initial bound state [i ) to the continuum (see Fig. 10.1a), we expand the lull time-dependent wave function as  

Here we have suppressed the channel (q) index for convenience, assuming that it is contained in the n index. As usual, we insert Eq. (10.2) into the time-dependent Schrodinger equation, iWW/dt — H Vit), and use the orthogonality of the eigenfunctions of Hm, to obtain an indenumerable set of first-order differential equations that are analogous to Eq. (2.3)  

Here we have retained the rotating-wave terms [see Eq. (2.13)] only. The detuning, Ae is given by 

Unlike the treatment in the weak-field domain, we do not assume that b (t) 1 at all times. Rather, we integrate the bE a continuum coefficients of Eq. (10.3) over, time, while imposing the boundary condition that the continuum states are empty at the start of the process [i.e., bE a(t - —oo) = 0], to obtain 

The value of the ground state coefficient at time t is seen to be determined by its past history at t t through the memor) kernel (t) (t )Fl(t — ir). 

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We consider now the case of dissociation by the net absorption of just one photon, to jjje1 termed one-photon dissociation. As in the weak-field domain (Chapter 3) the (molecule is assumed to dissociate into two fragments as a result of the interaction (with a laser pulse. It is convenient to parametrize the incident electric field [Eq. (1.35) as... 

M. Shapiro, Theory of one- and two-photon dissociation with strong laser pulses, J. Ghem. Phys. 101 (1994) 3844 E. Frishman, M. Shapiro, Reversibility of bound-to-continuum transitions induced by a strong short laser pulse and the semiclassical uniform approximation, Phys. Rev. A. 54 (1996) 3310. 

Shapiro, M., Theory of one- and two-photon dissociation with strong laser pulses, J. Chem. Phys., 101, 3844-3851, 1994. 

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