Intense-field molecular spectroscopy: Vibrational and rotational effects in harmonic generation by H2+

Abstract

We present results of a complete treatment of electronic, vibrational, and rotational motion in numerical calculation of harmonic generation (HG) of 1064-nm laser radiation by the ${\mathrm{H}}_{2}^{+}$ molecular ion for intensities ${10}^{13}$\ensuremath{\le}I\ensuremath{\le}${10}^{14}$ W/${\mathrm{cm}}^{2}$. We show that efficient HG can be enhanced by suppression of photodissociation, a phenomenon which results from vibrational trapping in laser-field-induced potential wells. The HG spectra exhibit peaks clustered around even and odd harmonic orders. All peaks can be assigned to Raman-like transitions between dressed eigenstates of the field-molecule system. Rotational excitation is shown to compete with HG. Thus harmonic generation and photon scattering in molecules holds the promise of a potential diagnostic for molecular stabilization by intense laser fields.