Two-Photon Excited State Dynamics of Dark Rydberg and Bright Valence States in Furan

Abstract

Two-photon absorption in systems with parity permits access to states that cannot be directly prepared by one-photon absorption. Here we investigate ultrafast internal conversion (IC) dynamics of furan by using this strategy in combination with femtosecond time-resolved photoelectron imaging. The dark Rydberg S1 and bright valence S2 states are simultaneously excited by two photons of 405 nm, and then ionized by two photons of 800 nm. The IC from S2 to S1 is clearly observed and extracted from the time dependence of the higher photoelectron kinetic energy (PKE) component. More importantly, the internal conversions to hot S0 from directly-prepared S1 and secondarily-populated S1 are unambiguously identified by the time-dependence of the lower PKE component. The average lifetime of the S2 and S1 states is measured to be 29 fs. The internal conversions of S2 to S1, S1 to hot S0 occur on estimated timescales of 15.4 fs and 38 fs, respectively.

Dissociative Ionization and Coulomb Explosion of Molecular Bromocyclopropane in an Intense Femtosecond Laser Field

“…Due to the importance in the field of atmospheric physics and environment chemistry, plenty of studies have been focused on the carbon halogen dissociation by single-photon excitation using ultraviolet laser field [8,9,10,11]. H.K.…”