SHEDDING NEW LIGHT ON THERMIONIC ELECTRON-EMISSION OF FULLERENES

Tunable pulsed infrared (IR) radiation from a free electron laser is u sed to selectively excite fullerenes via their vibrational modes to ve ry high internal energies. After absorbing several hundred IR photons, the molecules can autoionize. Ion creation is unexpectedly slow, occu rring at times beyond 0.1 ms after laser excitation, but is found to b e significantly faster for electronically preexcited molecules. It is concluded that reaching the first electronically excited state is a hi gh hurdle on the way from hot molecules to ions.