Femtosecond Two Photon Photoemission Spectroscopy of Methyl Iodide Adsorbed on a Gold Surface Available to Purchase

The adsorption behavior and the electronic structure of methyl iodide molecules on thin gold films grown on Mo(100) have been investigated by temperature programmed desorption spectroscopy and two photon photoemission spectroscopy. The repulsive first order thermal desorption of methyl iodide from the Au surface indicates that the majority of the molecules adsorbs without decomposition and with the molecular dipole axis oriented parallel to each other at submonolayer coverages. A decrease of the surface work function due to methyl iodide deposition is detected in the photoemission spectra. This supports a positive outward oriented dipole moment of the molecules. Time resolved two photon photoemission transients are presented and the measured time constants are interpreted in terms of the different excited states of the Au/Mo(100) substrate that are probed as a function of the detection wavelength and the methyl iodide coverage.