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