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Dissociation of Benzene Molecule in a
Strong Laser Field Thus, the Hamiltonian of the concerned system is The kinetic energy operator being of the form Where Re is the equilibrium internuclear separation. When calculating we make use of Re=1.39 A. The time dependent Schrodinger equation with Hamiltonian (3) has been solved numerically by the splitoperator method. The wave function has been derived by the iteration procedure according to formula The initial wave function (R,0) was chosen as the solution of the unperturbed problem for a particle in the ground state of Morse potential. The dissociation probability has been derived as a function of time according to formula W(t)=<(R,0)(R,t)>2 . In Fig. 3 envelope of laser pulse is depicted and the dissociation probability W(t) is shown in Fig. 4. 3. Results. The quantity W(t) is seen from Fig. 4 increase exponentially with time and it is equal to 0.11 after the end of laser pulse. It should be noted that the dissociation process can not be considered as a tunneling of a fragment through the effective potential barrier (see Fi. 2). Indeed, the tunneling probability is on the order of magnitude of Where Veff is substituted for maximum value of the field strength and the integral is derived over the classically forbidden region under the effective potential barrier. The tunneling effect is seen to be negligibly small due to large reduced mass of the molecular fragment 1. The Keldysh parameter =(2E)1/2/F>>1. Thus, the dissociation is the pure multiphoton process. The frequency of laser field is 2.7 эВ, while the dissociation potential is De=6 eV. Hence, threephoton process of dissociation takes place. The dissociation rate of threephoton process is proportional to 1/2. The total dissociation probability is obtained by means of multiplying of this rate by the pulse length . Therefore the probability of threephoton process can be large, unlike the tunneling probability. This is the explanation of large dissociation probability W0.11 obtained in the calculations. 4. Conclusions. Derivations given above of dissociation of benzene molecule show that approximately 11 of all C3H3+ions decay on fragments C3H3 and C3H3+ under the conditions of Ref. [4]. The absorption of three photons occurs in this process. Author is grateful to N. B. Delone, V. P. Krainov, M. V. Fedorov and S. P. Goreslavsky for stimulating discussions of this problem. This work was supported by Russian Foundation Investigations (grant N 960218299). References 1. Peter Dietrich, Donna T. Strickland, Michel Laberge and Paul B. Corkum, Phys. Rev. A, 47, N3, 2305 (1993). M. Ivanov, T. Siedeman, P. Corkum, Phys. Rev. A, 54, N2, 1541 (1996). 2. F. A. Ilkov, T. D. G. Walsh, S. Turgeon and S. L. Chin, Phys. Rev. A, 51, N4, R2695 (1995). скачать реферат 1 2 Не нашли нужную работу? Закажи реферат, курсовую, диплом на заказ Внимание! Студенческий отдых и мегатусовка после сессии!
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