中文摘要：

利用400nm的泵浦脉冲激发样品，通过瞬态吸收的实验研究分散在水中的氧化石墨烯-甲基蓝系统；同时，纯净的甲基蓝和氧化石墨烯的动力学也被分析．另外，利用全局分析拟合实验结果，获得了五个寿命：（0．61±0．01）ps，（3．52±0．04）ps，（14．1±0．3）ps，（84±2）ps和（3．66±0．08）ns．通过对比纯净的甲基蓝和氧化石墨烯-甲基蓝系统，发现了新的驰豫通道．

英文摘要：

The mixture of graphene oxide （GO） and dye molecules may provide some new applications due to unique electronic, optical, and structural properties. Methylene blue （MB）, a typ- ical anionic dye, can attach on GO via π-π stacking and electrostatic interaction, and the molecule removal process on GO has been observed. However, it remains unclear about the ultrafast carrier dynamics and the internal energy transfer pathways of the system which is composed of GO and MB. We have employed ultrafast optical pump-probe spectroscopy to investigate the excited dynamics of the GO-MB system dispersed in water by exciting the samples at 400 nm pump pulse. The pristine MB and GO dynamics are also analyzed in tandem for a direct comparison. Utilizing the global analysis to fit the measured signal via a sequential model, five lifetimes are acquired：（0.61±0.01） ps, （3.52±0.04） ps, （14.1±0.3） ps, （84±2） ps, and （3.66±0.08） ns. The ultrafast dynamics corresponding to these lifetimes was analyzed and the new relaxation processes were found in the GO-MB system, compared with the pristine MB. The results reveal that the functionalization of GO can alter the known decay pathways of MB via the energy transfer from GO to MB in system, the increased intermediate state, and the promoted energy transfer from triplet state MB to ground state oxygen molecules dissolved in aqueous sample.