| A tremendous group of the layered materials,as a representative of van der Waals semiconductors,featured with complete and diverse system,unique and rich structure,are enrich in excellent physical and chemical properties and have a wide range of great potential applications in the fields of optoelectronics,information and energy.And also,they are also one of the hotspots in condensed matter physics and optoelectronics.In addition,as a unique propertie of the noble metals and the two-dimensional van der Waals materials,surface plasmons can effectively enhance the nonlinear effect of the medium,which can be used to realize optical field regulation,new device development,biological diagnosis and treatment,etc.The main context and results are illustrated as follows:(1)Study on polarization-dependent interfacial charge transfer excitons enhanced by graphene plasmon in 2D graphene-black phosphorus heterostructures.The physical mechanism of polarization-dependent on interfacial charge transfer excitons enhanced by graphene plasma is theoretically explained in in two different structures of G-BP and G-BP-G heterojunction.Further the research indicates that BP can be protected by graphene from the chemical reaction in surrounding oxygen and water in ambient conditions.In addition,there are strong interfacial charge transfer excitons in NIR and MIR regions.The structure can be used as wavelengthand anisotropy-dependent photodetectors in NIR and MIR regions.(2)Study on external electric field manipulating sequential and superexchange charge transfer in donor-bridge-acceptor system in two-photon absorption(TPA).Firstly,the self-developed two-photon absorption calculation program based on SOS model is adopted to realize external electric field manipulates sequential and super-exchange charge transfer in donor-bridgeacceptor(D-B-A)system.The optical charge transfer process can be visualized and further solve the problem that charge transfer cannot be analyzed by the theory of quadratic response during the two-photon absorption transition.It is found that optimal external electric fields,including direction and strength,can facilitate the sequential and super-exchange charge transfer in the same direction in the two step transitions in TPA,which can promote the charge separation and transfer in D-B-A system in TPA.(3)Study on synthesis of homogeneous carbon quantum dots by the self-built ultrafast dual-beam pulsed laser ablation for bioimaging.CQDs have been fabricated through ablation of low-cost carbon cloth with the orthogonal pulsed laser doublebeam for shortening laser ablation time and improving the yield by avoiding the influence of impurities caused by the introduction of various solvents.Compared with single laser beam ablation,the size of carbon quantum dots prepared by double beam laser ablation is more uniform,and the yield of fluorescent quantum dots is as high as 35.4%.The fluorescence emission mechanism is further clarified by the discovery of fluorescence emission spectra,which is attributed to the transition of π*state electron to surface state.Finally,CQDs with good stability and excellent antijamming performance show excellent bioimaging ability.Therefore,we propose an ultrafast preparation method to fabricate homogeneous CQDs with high quantum yield for the study of PL emission mechanism and cell bioimaging.(4)Study on In situ Plasmon-Enhanced CARS and TPEF for Gram staining identification of non-fluorescent bacteria.We develop in situ simultaneously measurement methods on plasmon-enhanced CARS and TPEF for nonfluorescence in vivo biologic samples.With our synthesized Au@Ag nanorod with vigorous SPR intensity,plasmon can enhance the fundamental and double frequency forTPEF,as well as enhance CARS.In addition,calculations with complete active space self-consistent field(CASSCF)reveals the hot electrons of SPs can efficiently induce the biological fluorescence of non-fluorescent flavin nucleotides on the surface of E.coli.The CARS signal can be used to classify microorganism types by Gram staining in vivo. |
