We have fabricated C_(70) film by physical jet deposition(PJD)technique and measured the absorption and photoluminescence(PL)spectra of this End C_(70) film.In comparison with the deposited C_(70) film in high vacuum,...We have fabricated C_(70) film by physical jet deposition(PJD)technique and measured the absorption and photoluminescence(PL)spectra of this End C_(70) film.In comparison with the deposited C_(70) film in high vacuum,the absorption and integrated PL spectra are similar,but there is a big difference in the time-resolved PL.The C_(70) film made by PJD shows a very fast PL decay of less than 20ps which should result from the fast relaxation process of C_(70) molecule in the excited state S_(1) of this new kind film.展开更多
Using a picosecond excitation source and a time-resolved streak camera detection system,the time-resolved fluorescence spectra of purified C_(60) have been recorded from toluene solution at room temperature.A fluoresc...Using a picosecond excitation source and a time-resolved streak camera detection system,the time-resolved fluorescence spectra of purified C_(60) have been recorded from toluene solution at room temperature.A fluorescence peak at about 730nm was detected and its lifetime was directly determined to be 1.1±0.1 ns.Two fluorescence peaks obtained from the mixture of C_(60) and C_(70) at 676 and 696nm were mainly related to C_(70) content.展开更多
We have measured the power dependence of the photoluminesence spectra from a set of strained In_(x)Ga_(1-x)As/GaAs single quantum wells.The result shows that the excitation power has important effect on the carrier re...We have measured the power dependence of the photoluminesence spectra from a set of strained In_(x)Ga_(1-x)As/GaAs single quantum wells.The result shows that the excitation power has important effect on the carrier recombination processes.When the power increases from 0.5 to 14mW,the photoluminescence from the barrier becomes more intense than that from the well and the trapping efficiency decreases.At high excitation level,the ratio of the radiative recombination rate to the nonradiative recombination rate of the barrier increases ten times than that at lower excitation level,while it only doubles for the well.展开更多
We have measured the time-resolved photoluminescence spectra of several In_(x)Ga_(1-x)As/GaAs single quantum well samples at 77K.The different temporal behaviors of the photoluminescence(PL)from the GaAs layer and the...We have measured the time-resolved photoluminescence spectra of several In_(x)Ga_(1-x)As/GaAs single quantum well samples at 77K.The different temporal behaviors of the photoluminescence(PL)from the GaAs layer and the excitonic emission from the In_(x)Ga_(1-x)As well were obtained.The lifetime for the exciton in the In_(x)Ga_(1-x)As well were determined to be 110-170ps.The trapping efficiency of the well to the carriers was about 80%.展开更多
Under the Na vapor,states was near resonant radiation field-atom interaction in large population difference between 3^(2)P_(1/2)and 3^(2)P_(3/2)generated,then occurred the excited state stimulated Raman Scattering(ESS...Under the Na vapor,states was near resonant radiation field-atom interaction in large population difference between 3^(2)P_(1/2)and 3^(2)P_(3/2)generated,then occurred the excited state stimulated Raman Scattering(ESSRS).By the sequential four-wave mixing(FWM)process,multi-line ESSRS and the buffer gas effeet have been observed.A theory has been developed to explain the experimental results.展开更多
We have measured the picosecond Stokes oscillation from CC14,C_(6)H_(6) and other droplets with about 70 micrometer diameter.The obtained oscillation can reach 8th order.The explanation for the differences between the...We have measured the picosecond Stokes oscillation from CC14,C_(6)H_(6) and other droplets with about 70 micrometer diameter.The obtained oscillation can reach 8th order.The explanation for the differences between the Stokes oscillations with nanosecond and picosecond pumping is given.展开更多
Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subse-quently annealing method. Z-scan technique, femtosecond time-resolved optical Kerr effect (OKE) technique and femtosecond...Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subse-quently annealing method. Z-scan technique, femtosecond time-resolved optical Kerr effect (OKE) technique and femtosecond pump-probe experiment were used to investigate the effects of laser wavelength and laser pulse duration as well as annealing temperature on the third-order optical nonlinearity and ultrafast dynamics of the composites. It was found that the third-order susceptibility of Ag nanoparticles composite glass measured by 400 nm pulse source is larger than that measured by 800 nm pulse source due to an enhancement effect of local field near surface plasmon resonance of Ag nanoparticles in silicate glass. The third-order optical nonlinearity measured by ns laser source is about two orders of magnitude larger than that measured from fs pulse. The annealing temperature has an important effect on the third-order optical nonlinearity and ultrafast dynamics of the composites. Third-order nonlinear susceptibility up to 10?10 esu and fast relaxation process up to 0.2 ps have been obtained in Ag nanoparticles doped glass.展开更多
Photodynamics of peripheral antenna complexes,light-harvesting complex (LH2) of Rhodobacter (Rb) Sphaeroides 601,was studied using femtosecond pump-probe technique at different laser wavelengths. The obtained results ...Photodynamics of peripheral antenna complexes,light-harvesting complex (LH2) of Rhodobacter (Rb) Sphaeroides 601,was studied using femtosecond pump-probe technique at different laser wavelengths. The obtained results reveal dramatic dynamical evolutions within B800 and B850 absorption bands of antenna complexes LH2. At excitation wavelength around 835 nm,a sharp photobleaching signal was observed which was assigned to the contribution of the two-exciton state,which was further confirmed by the power dependence measurement. Rate equations with eight-level scheme were used to calculate the population evolution in LH2 and the transient dynamics under femtosecond pulse excitation. The research results prove that not only the transition from ground state to one-exciton state but also that from one-exciton state to two-exciton state contribute to the photodynamics of B850.展开更多
文摘We have fabricated C_(70) film by physical jet deposition(PJD)technique and measured the absorption and photoluminescence(PL)spectra of this End C_(70) film.In comparison with the deposited C_(70) film in high vacuum,the absorption and integrated PL spectra are similar,but there is a big difference in the time-resolved PL.The C_(70) film made by PJD shows a very fast PL decay of less than 20ps which should result from the fast relaxation process of C_(70) molecule in the excited state S_(1) of this new kind film.
文摘Using a picosecond excitation source and a time-resolved streak camera detection system,the time-resolved fluorescence spectra of purified C_(60) have been recorded from toluene solution at room temperature.A fluorescence peak at about 730nm was detected and its lifetime was directly determined to be 1.1±0.1 ns.Two fluorescence peaks obtained from the mixture of C_(60) and C_(70) at 676 and 696nm were mainly related to C_(70) content.
文摘We have measured the power dependence of the photoluminesence spectra from a set of strained In_(x)Ga_(1-x)As/GaAs single quantum wells.The result shows that the excitation power has important effect on the carrier recombination processes.When the power increases from 0.5 to 14mW,the photoluminescence from the barrier becomes more intense than that from the well and the trapping efficiency decreases.At high excitation level,the ratio of the radiative recombination rate to the nonradiative recombination rate of the barrier increases ten times than that at lower excitation level,while it only doubles for the well.
文摘We have measured the time-resolved photoluminescence spectra of several In_(x)Ga_(1-x)As/GaAs single quantum well samples at 77K.The different temporal behaviors of the photoluminescence(PL)from the GaAs layer and the excitonic emission from the In_(x)Ga_(1-x)As well were obtained.The lifetime for the exciton in the In_(x)Ga_(1-x)As well were determined to be 110-170ps.The trapping efficiency of the well to the carriers was about 80%.
文摘Under the Na vapor,states was near resonant radiation field-atom interaction in large population difference between 3^(2)P_(1/2)and 3^(2)P_(3/2)generated,then occurred the excited state stimulated Raman Scattering(ESSRS).By the sequential four-wave mixing(FWM)process,multi-line ESSRS and the buffer gas effeet have been observed.A theory has been developed to explain the experimental results.
文摘We have measured the picosecond Stokes oscillation from CC14,C_(6)H_(6) and other droplets with about 70 micrometer diameter.The obtained oscillation can reach 8th order.The explanation for the differences between the Stokes oscillations with nanosecond and picosecond pumping is given.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50672069, 10674031)the Key Item for Basic Research of Shanghai, China (Grant No. 05JC14058)
文摘Ag nanoparticles embedded in soda-lime silicate glass were fabricated by ion-exchange and subse-quently annealing method. Z-scan technique, femtosecond time-resolved optical Kerr effect (OKE) technique and femtosecond pump-probe experiment were used to investigate the effects of laser wavelength and laser pulse duration as well as annealing temperature on the third-order optical nonlinearity and ultrafast dynamics of the composites. It was found that the third-order susceptibility of Ag nanoparticles composite glass measured by 400 nm pulse source is larger than that measured by 800 nm pulse source due to an enhancement effect of local field near surface plasmon resonance of Ag nanoparticles in silicate glass. The third-order optical nonlinearity measured by ns laser source is about two orders of magnitude larger than that measured from fs pulse. The annealing temperature has an important effect on the third-order optical nonlinearity and ultrafast dynamics of the composites. Third-order nonlinear susceptibility up to 10?10 esu and fast relaxation process up to 0.2 ps have been obtained in Ag nanoparticles doped glass.
基金the National Natural Science Foundation of China (Grant No.10674031)
文摘Photodynamics of peripheral antenna complexes,light-harvesting complex (LH2) of Rhodobacter (Rb) Sphaeroides 601,was studied using femtosecond pump-probe technique at different laser wavelengths. The obtained results reveal dramatic dynamical evolutions within B800 and B850 absorption bands of antenna complexes LH2. At excitation wavelength around 835 nm,a sharp photobleaching signal was observed which was assigned to the contribution of the two-exciton state,which was further confirmed by the power dependence measurement. Rate equations with eight-level scheme were used to calculate the population evolution in LH2 and the transient dynamics under femtosecond pulse excitation. The research results prove that not only the transition from ground state to one-exciton state but also that from one-exciton state to two-exciton state contribute to the photodynamics of B850.
