Intramolecular dynamics and multiresonant absorption spectroscopy. I. Reduced non-Franck–Condon intensity in the high-power two-photon absorption spectrum of NO2

Publisher Website
Google Scholar
Abstract
The two-photon absorption spectrum of the X 2A1→3pσ 2∑+u transition in NO2 shows prominent Franck–Condon forbidden origins. The absolute intensities of these non-Franck–Condon transitions, as seen by ionization, diminishes at high power. A dense system of dissociative states lies intermediate at the level of the first photon. These states are highly mixed in either bent or linear zeroth-order basis, and thus at low power effectively bridge bent-to-linear origins. At high laser intensity, power (lifetime) broadening prepares a superposition state with the optical character of the ground state and thus poor overlap with low-lying linear excited states. The preparation and projection of this zeroth-order, nonstationary intermediate state bears strong analogy to similar absorption and fluorescence processes stimulated by picosecond pulses.