Theory of high-order harmonic generation from molecules by intense laser pulses

LE, ANH-THU; DELLA PICCA, R.; FAINSTEIN, P. D.; TELNOV, D. A.; LEIN, M.; LIN, C. D.

JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS

IOP PUBLISHING LTD

Lugar: Bristol; Año: 2008 vol. 41 p. 81002 - 81002

0953-4075

We show that high-order harmonics generated from molecules by intenselaser pulses can be expressed as the product of a returning electronwave packet and the photo-recombination cross section where the electronwave packet can be obtained from the simple strong-field approximation(SFA) or from a companion atomic target. Using these wave packets butreplacing the photo-recombination cross sections obtained from SFA orfrom the atomic target by the accurate cross sections from molecules,the resulting high-order harmonic spectra are shown to agree well withthe benchmark results from direct numerical solution of thetime-dependent Schrödinger equation, for the case ofH+2 in laser fields. The result illustrates thatthese powerful theoretical tools can be used for obtaining high-orderharmonic spectra from molecules. More importantly, the results implythat the photo-recombination cross section extracted from laser-inducedhigh-order harmonic spectra can be used for time-resolved dynamicchemical imaging of transient molecules with temporal resolutions downto a few femtoseconds.