Photoluminescence from amorphous carbon grown by laser ablation of graphite

Abstract

Photoexcitation and photoluminescence (1–7 eV) spectra of amorphous carbon films grown by laser ablation of a graphite target have been measured. The experimental data obtained are analyzed using the sum rule, and the energy dependence of the effective electron density of states is determined. Characteristic threshold energies in the effective density of states are revealed at ∼1.4 and ∼4 eV, and the conclusion is made that the energy distribution of the density of states is nonuniform, which is attributed to different contributions from the σ and π states of electrons. The temperature of the electron system excited by light is estimated to exceed the lattice temperature by a factor of ∼40. This circumstance is attributed to heating of electrons by light.