Infrared-laser-pulse control of bond- and state-selective excitation, dissociation and space quantization: application to a three-dimensional model of HONO2 in the ground electronic state |
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Authors: | M Oppel GK Paramonov |
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Institution: | Institut für Chemie–Physikalische und Theoretische Chemie, Freie Universit?t Berlin, Takustrasse 3, 14195 Berlin, Germany (Fax: +49-30/838-4792, E-mail: paramon@chemie.fu-berlin.de), DE
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Abstract: | Selective control over the vibrational excitation and space quantization of the dissociation fragments by optimally designed
linearly polarized and shaped infrared (IR) laser pulses of the picosecond (ps) and subpicosecond duration is demonstrated
by means of quantum-dynamical simulations within the Schr?dinger wave-function formalism for a three-dimensional (3-D) model
of HONO2 in the ground electronic state, wherein the OH and the ON single-bond stretches are explicitly treated, together with the
bending angle between them, on the basis of the ab initio defined 3-D potential-energy surface and dipole function. The high-lying
zeroth-order vibrational states of the OH bond are prepared selectively both below and above the dissociation threshold of
the ON single bond, and demonstrate a quasi-periodic oscillatory behaviour, manifesting intramolecular vibrational energy
redistribution (IVR) on the picosecond timescale. Selective breakage of the ON single bond in HONO2 with more than 97% probability is demonstrated, along with control of the space quantization of the dissociation fragments:
the OH fragments rotating clockwise, OH(c), and anticlockwise, OH(a), are prepared selectively, with the OH(a)/OH(c) branching
ratio being as high as 10.975. The results obtained show that optimally designed strong and short IR-laser pulses can compete
against IVR and manipulate vibrational excitation and dissociation of polyatomic molecules.
Received: 3 November 1999 / Published online: 13 July 2000 |
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Keywords: | PACS: 33 80 Gj 33 80 Rv 34 50 Ez |
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