Two-photon photoelectron spectrum of methyl iodide through a dissociative intermediate state

The two-photon photoelectron spectrum of methyl iodide was recorded in a magnetic bottle time-of-flight spectrometer. As absorption of the first photon is resonant with the dissociative A-state continuum of methyl iodide, the experiment corresponds to a bound-free-bound transition. A progression in the C-I stretching vibration is observed, which corresponds, in a simplified picture, to the dissociation coordinate. The results agree well with recently published two-photon ZEKE spectra of CH3I. This similarity has impact on an ongoing discussion about discrepancies between calculated and measured intensities in two-photon ionization spectra.close111

Ultrafast dynamics through conical intersections and intramolecular vibrational energy redistribution in styrene

We report a femtosecond time-resolved photoelectron spectroscopy (TRPES) investigation of internal conversion in the first two excited singlet electronic states of styrene. We find that radiationless decay through an S1/S0 conical intersection occurs on a timescale of 4 ps following direct excitation to S1 with 0.6 eV excess energy, but that the same process is significantly slower (20 ps) if it follows internal conversion from S2 to S1 after excitation to S2 with 0.3 eV excess energy (0.9 eV excess energy in S1).<br/