Investigation of the luminescence properties of ZnO clusters induced by single-photon and two-photon excitation

Abstract

By using a luminescence spectrometer and femtosecond laser, we have investigated the specific optical properties and excitation mechanism of ZnO clusters with one-photon and two-photon excitations. When the excitation wavelength was chosen to be 360 nm, the strongest luminescence intensity was observed. However, the luminescence intensity decreased gradually and the emission peak was red shifted slowly with increasing excitation wavelength (from 360 to 400 nm). When the excitation wavelength was chosen to be 780 nm, the luminescence intensity increased nonlinearly with increasing excitation intensity. What is even more interesting is that ZnO clusters could be used in the imaging of living cells under two-photon excitation, implying the potential applications for the optical properties of ZnO clusters in the field of biophotonics.