Quantum-beat imaging of the nuclear dynamics in D_2^[+]: Dependence of bond softening and bond hardening on laser intensity, wavelength, and pulse duration
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Based on a quantum-mechanical model, we calculate the time evolution of an initial nuclear vibrational wave packet in D2+ generated by the rapid ionization of D2 in an ultrashort pump-laser pulse. By Fourier transformation of the nuclear probability density with respect to the time delay between the pump pulse and the instant destructive Coulomb-explosion imaging of the wave packet at the high-intensity spike of an intense probe-laser pulse, we provide two-dimensional internuclear-distance-dependent power spectra that serve as a tool for visualizing and analyzing the nuclear dynamics in D2+ in an intermittent external laser field. The external field models the pedestal to the central ultrashort spike of a realistic probe pulse. Variation in the intensity, wavelength, and duration of this probe-pulse pedestal (i) allows us to identify the optimal laser parameters for the observation of field-induced bond softening and bond hardening in D2+ and (ii) suggests a scheme for quantitatively testing the validity of the "Floquet picture" that is commonly used for the interpretation of short-pulse laser-molecule interactions, despite its implicit "continuum wave" (infinite pulse length) assumption.
Physical Review A
Copyright 2009 American Physical Society. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Atomic and Molecular Physics