Time-dependent spectrum of thermionic emission from hot C60

Experimental measurements of time-dependent photoelectron spectra observed in thermionic emission of hot C₆₀ excited by multiphoton absorption are presented. Time resolved velocity-map imaging is used to record photoelectron spectra and to disentangle direct and delayed processes. The evolution of the kinetic energy distribution of thermal electrons as a function of the delay after multiphoton excitation is described within the general formalism of the detailed balance theory. Experimental spectra obtained in the near-UV are in excellent agreement with the assumption of thermal equilibrium.