Time-dependent spectrum of thermionic emission from hot clusters: Model and example ofC60

Abstract

We have studied the evolution of the kinetic energy distribution of thermal electrons emitted from energyrich clusters as a function of the delay after multiphoton excitation. In this paper we emphasize the description of thermionic emission based on the general formalism of the detailed balance theory. Our description accounts for competing decay channels and underlines the fundamental role of the observation time window. Simulations including two decay channels (namely, delayed electron emission and loss of C 2 fragments) are compared with experimental results in the case of hot fullerenes C 60 . The most striking result of the model is the close connection between the effective temperature of the electron distribution and the time delay of observation. Our model is in very good agreement with our experimental measurements of time-dependent photoelectron spectra.

Evidence for cluster shape effects on the kinetic energy spectrum in thermionic emission

“…This system has been upgraded to allow for time-resolved measurements on a time scale compatible with thermionic processes. As was shown previously, 6 the fast variations of the emission rate determine the internal energy of the cluster observed at a given time delay. This technique has been previously described 15 and successfully used in the study of C 60 .…”

Intensity-resolved IR multiple photon ionization and fragmentation of C60

“…In highly excited C 60 energy release in the form of ionization (thermionic emission), fragmentation and radiative emission have been observed [3][4][5][6][7][8] . C 60 has also played an important role in the understanding of infrared (IR) multiple-photon excitation (IR-MPE) spectroscopy.…”

Single-Size Thermometric Measurements on a Size Distribution of Neutral Fullerenes

“…Time-resolved electron velocity distributions were measured at various time delays. The analysis of such measurements and the information contained in the timedependent spectra were explained in a previous article [6].…”

“…d the dissociation prefactor and the emission temperature T e is defined by T e % T ðE À E d =2Þ (see Ref. [6]). We have determined ðE d ; !…”