Ultrafast laser control of vibrational dynamics for a two-dimensional model of HONO2 in the ground electronic state:: separation of conformers, control of the bond length, selective preparation of the discrete and the continuum states

Selective excitation of the vibrational bound and the continuum states, controlled by subpicosecond infrared (IR) laser pulses, is simulated within the Schrodinger wave function formalism for a two-dimensional model of the HONO2 molecule in the ground electronic state. State-selective excitation of the OH bond is achieved by single optimal laser pulses, with the probability being 97% for the bound states and more than 91% for the resonances. Stable, long-living continuum states are prepared with more than 96% probability by two optimal laser pulses, with the expectation energy of the molecule being well above the dissociation threshold of the ON single bond, and its life-time being at least 100 ps. The length of the ON single bond can be controlled selectively: stretching and contraction by about 45% of its equilibrium length are demonstrated. Laser separation of spatial conformers of HONO2 in inhomogeneous conditions occurring on an anisotropic surface or created by a direct current (DC) electric field is analysed. The relative yields of target conformers may be very high, ranging from 10 to 10(8), and the absolute yields of up to 40% and more are calculated. (C) 1998 Elsevier Science B.V. All rights reserved.