▎ 摘　　要

We have studied the effects of laser fluence on the characteristics of graphene nanosheets produced by pulsed laser ablation technique. In this work, The second harmonic of a Q-switched Nd: YAG laser at 532 nm wavelength and 5 Hz repetition rate with different laser fluences in the range of 0.5-1.8 J/cm(2) was used to irradiate the graphite target in liquid nitrogen medium. The products of ablation were characterized using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction pattern, UV-Vis absorption spectroscopy, Raman spectrum and transmission electron microscopy. The Raman spectroscopy indicates that the quality of the graphene nanosheets was decreased while their structure defects were increased as the laser fluence was increased from 0.5 to 1.4 J/cm(2). Our results suggest that the amount of defects and the number of layers in graphene nanosheets can be changed by adjusting the laser fluence. This study could be a useful guidance for producing of high quality of graphene nanosheets by laser ablation method.