Studies On Ultrafast Dynamics Of Anthraquinone Derivatives Compounds By Transient Absorption Spectroscopy

A series of dynamic processes are easy to occur in high energy molecular excited states.We call these instantaneous dynamic processes ultra-fast dynamic processes.Proton transfer in ultrafast dynamics is of great interest.In-depth study of this process is helpful to understand the basic principle of proton transfer process and apply it to different production fields.Proton transfer occurs when the anthraquinone derivatives are excited by femtosecond pulses.Therefore,anthraquinone derivatives become an important system for proton transfer.Femtosecond time-resolved transient absorption spectroscopy is an important tool in the study of ultrafast kinetic processes of anthraquinone derivatives.The advent of femtosecond time-resolved transient absorption spectroscopy makes it possible to detect the proton transfer process of anthraquinone derivatives.In this paper,the ultrafast dynamics processes of 1,8-DHAQ and 1,2-DHAQ anthraquinone derivatives were studied by using this technique.The content of this paper is mainly divided into two parts:In the first part,1,8-DHAQ was selected as the research system,and the proton transfer and vibration relaxation processes of the system were studied by using time-resolved transient absorption spectroscopy.The time scale of proton transfer in 1,8-DHAQ was 96.8 fs.The tautomer generated after proton rotation will produce a vibration relaxation process,and its time scale is 4.1 ps.Subsequently,the tautomer underwent a fluorescence process of 269.1 ps and returned to the ground state with lower energy through this process.Through data analysis and fitting,the kinetic curves of proton transfer and vibrational relaxation are obtained,which directly reveal the proton transfer and vibrational relaxation processes.In the second part,1,2-DHAQ was selected as the research system,and the pumping wavelength used to measure this system was 370 nm.The proton transfer of 1,2-DHAQ and the subsequent ultrafast kinetic processes were investigated using the same techniques and methods as those of 1,8-DHAQ.By analyzing the spectral signal,a more accurate time scale of the dynamic process was obtained.The results show that 1,2-DHAQ has proton transfer process,which takes 110.5 fs.After proton transfer,its structure will change,and its tautomer will go through a series of vibration relaxation processes,with a time of 30.7ps.The tautomer in the higher energy state will release the photon to return to the ground state,and the fluorescence process was 131.7 ps.