Inelastic Interaction of an Electron with a C60 Cluster

The method of intersecting beams of C₆₀ fullerene clusters and of electrons is used to investigate the production of C₆₀⁺ and C₆₀^– ions and the radiation in the wavelength range from 300 to 800 nm for the electron energy E_e ranging from zero to 100 eV. The absolute values of the ionization and electron-attachment cross sections [⁺(E_e) and ^–(E_e), respectively] are determined. A maximum of ⁺(E_e) of 0.53 nm²is observed at E_e = 52 eV. For a C₆₀ cluster excited by electron impact, delayed (150 s) ionization initiated by collision with the surface and ionization due to thermionic emission (its characteristic time at E_e = 60 eV is 6 s) is observed. It is found that, for E_e < 0.4 eV, the formation of C₆₀^– is defined by the polarization capture of an s-electron (^– E_e^–1), and a formula is suggested for determining ^–(E_e). In the region of E_e from 1 to 6 eV, the cross section ^–(E_e) shows only slight variations about ^–(E_e) = 0.36 ± 0.03 nm². For E_e > 7.5 eV, C₆₀^– ions proved to be unstable to electron autodetachment. In the region of intersection of C₆₀ and electron beams, radiation of a quasicontinuous spectrum described by a modified Planck formula for the thermal emission of spherical particles of diameter d is recorded. For E_e > 47 eV, the brightness temperature proved to be 3150 ± 50 K. It is found that this radiation is emitted predominantly by hot C₆₀^+* ions produced as a result of thermionic emission from C₆₀^*. The rate of radiation loss of energy by a C₆₀^+* ion and the cross section for the formation of radiating C₆₀^+* ions are found to be, respectively, 5.5 × 10⁵ eV/s at T = 3150 K and 2 × 10^–2 nm² at E_e = 60 eV.