The ultrafast exciton trapping dynamics in ZnSe/ZnCdSe short period superlattice quantum wells has been studied by using transient photoluniinescence spectroscopy.A rapid exciton trapping time of less than 7 ps from t...The ultrafast exciton trapping dynamics in ZnSe/ZnCdSe short period superlattice quantum wells has been studied by using transient photoluniinescence spectroscopy.A rapid exciton trapping time of less than 7 ps from the barriers to the wells is measured.In Te doped samples self-trapped excitons give rise to Stokes shifted broad band luminescence and exhibit much longer lifetime.展开更多
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
The molecules formed in a structure of A-π-D possess large hyperpolarizability β, in which A is an acceptor, D is a donor, and π is an electronic bridge connecting A and D. From such molecules one can make poled po...The molecules formed in a structure of A-π-D possess large hyperpolarizability β, in which A is an acceptor, D is a donor, and π is an electronic bridge connecting A and D. From such molecules one can make poled polymer films of large second-order展开更多
Cage-shaped carbon cluster-fullerene-is a new condensed state of carbon, whichis different from graphite and diamond. Fullerene C<sub>60</sub> which has the truncatedicosahedron structure is the most inten...Cage-shaped carbon cluster-fullerene-is a new condensed state of carbon, whichis different from graphite and diamond. Fullerene C<sub>60</sub> which has the truncatedicosahedron structure is the most intensively studied one because of its large amountin synthesis. Using different analysis and calculation methods, one can obtain differ-ent energy band gaps of C<sub>60</sub> solid ranging from 2.6 to 1.5 eV. As to C<sub>60</sub> molecule,using LDA method, the gap from HOMO （highest occupied molecular orbit） toLUMO （lowest unoccupied molecular orbit）is 1.9 eV, while using SSH model,展开更多
基金Supported by the National Natural Science Foundation of China.
文摘The ultrafast exciton trapping dynamics in ZnSe/ZnCdSe short period superlattice quantum wells has been studied by using transient photoluniinescence spectroscopy.A rapid exciton trapping time of less than 7 ps from the barriers to the wells is measured.In Te doped samples self-trapped excitons give rise to Stokes shifted broad band luminescence and exhibit much longer lifetime.
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.
基金Project supported by Guangdong Provincial Science Foundation.
文摘The molecules formed in a structure of A-π-D possess large hyperpolarizability β, in which A is an acceptor, D is a donor, and π is an electronic bridge connecting A and D. From such molecules one can make poled polymer films of large second-order
基金Project partly supported by the Excitation Process Laboratory in Changchun Institute of Physics, Academia Sinica.
文摘Cage-shaped carbon cluster-fullerene-is a new condensed state of carbon, whichis different from graphite and diamond. Fullerene C<sub>60</sub> which has the truncatedicosahedron structure is the most intensively studied one because of its large amountin synthesis. Using different analysis and calculation methods, one can obtain differ-ent energy band gaps of C<sub>60</sub> solid ranging from 2.6 to 1.5 eV. As to C<sub>60</sub> molecule,using LDA method, the gap from HOMO （highest occupied molecular orbit） toLUMO （lowest unoccupied molecular orbit）is 1.9 eV, while using SSH model,
