Gas-phase C-84 is resonantly excited using infrared (IR) radiation from a f
ree electron laser. At specific wavelengths, strong ion signals are observe
d, resulting from thermionic emission of electrons by the fullerenes. The m
ass-selected ion yield is recorded as a function of IR frequency and the re
sulting spectrum yields information on the electronic ground state of the g
as-phase molecule. (C) 1999 Elsevier Science B.V. All rights reserved.