Quantum Confinement Effect in Diamond Nanocrystals Studied by X-Ray-Absorption Spectroscopy

This study measures the x-ray-absorption spectra of a series of nanodiamond thin films with grain diameters ranging from 3.5 nm to $5\mu \mathrm{m}$ at the C $K$-edge using the sample drain current mode at room temperature. Resonance peaks resembling the C $1s$ core exciton are observed. The exciton state and conduction band edge are found to shift to higher energies with the decrease of the grain size indicative of the presence of the quantum confinement effect.