IR-REMPI spectroscopy for thermometry of C60

Gas-phase C60 molecules are excited with a 30 ps 266 nm Nd:YAG laser, followed by a train of high-power infrared (IR) sub-picosecond pulses from a free electron laser (FEL), which resonantly heats the molecules up to internal energies at which they efficiently undergo delayed ionization. By tuning the IR laser wavelength, IR-REMPI spectra are obtained. These are compared to simulations, giving detailed insight into the influence of UV pre-excitation on the IR laser ionization process of C60 molecules.