A double-potential-well model is proposed to describe the core-shell thickness-dependent photoluminescence peaks and energy relaxations in semiconductor quantum dots (QDs). The surface effect plays an important role i...A double-potential-well model is proposed to describe the core-shell thickness-dependent photoluminescence peaks and energy relaxations in semiconductor quantum dots (QDs). The surface effect plays an important role in the formation of new states-polaronic states around the surface of QDs. The polaronic states formed emit light due to the strong interaction between the core state (confined state) and the surface state with an enhanced participation of the size effect.展开更多
The emission and Fourier transformation infrared spectra of freshly prepared porous silicon(PS) and the silicon wafer were examined. Increasing temperature generally led to a decrease in the emission intensities of th...The emission and Fourier transformation infrared spectra of freshly prepared porous silicon(PS) and the silicon wafer were examined. Increasing temperature generally led to a decrease in the emission intensities of the PS samples, however, the freshly prepared sample showed an unusually large and sudden increase in its emission intensity at the specific temperature at which the hydrogen ion conductivity in the silicon wafer increased. The O-H vibrations of the silicon wafer also showed a sudden decrease at the same temperature. These results are consistent with the assumption that the luminescence of fresh PS comes from the carrier bound exciton in its confined nanostructure.展开更多
The structure and physical properties of carbon nanotubes have been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at pressures up to 50.7 GPa.At atmospheric...The structure and physical properties of carbon nanotubes have been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at pressures up to 50.7 GPa.At atmospheric pressure,the structure of carbon nanotubes is similar to the hexagonal close-packed lattice of graphite with the interplanar spacing of the diffraction line(002)d002=0.3404 nm and that of the line(100)d100=0.2116 nm.According to the high pressure x-ray diffraction results,the diffraction line(002)is broadened and weakened above 8 GPa,and carbon nanotubes become partly amorphous.When the pressures of 10 and 20 GPa are decreased down to zero,the diffraction line(002)is partly recovered.While at the maximum pressure of 50.7 GPa,they entirely become amorphous and this amorphous transition is irreversible.We used the equation of state of Birch-Murnaghan to fit the P-V data of carbon nanotubes and obtained the bulk modulus K0=54.3±3.2 GPa(at K'0=4.0).展开更多
Twelve new features from our Raman measurements of C_(70) have been observed by using the silver surface enhanced Raman scattering substrate with very high enhanced factor and highly sensitive Raman set.The results an...Twelve new features from our Raman measurements of C_(70) have been observed by using the silver surface enhanced Raman scattering substrate with very high enhanced factor and highly sensitive Raman set.The results and discussion in this letter would make new knowledge to vibration modes of C_(70).The experimental data of the study confirm the validity of Jishi's calculation with a small error.展开更多
The carbon-nitride thin films were deposited on the(100)oriented single-crystai KC1 wafers at ambient temperatures by using rf-plasma sputtering.The IR spectrum showed that the Ulins contained carbqn-nitnde bonds.The ...The carbon-nitride thin films were deposited on the(100)oriented single-crystai KC1 wafers at ambient temperatures by using rf-plasma sputtering.The IR spectrum showed that the Ulins contained carbqn-nitnde bonds.The transmission electron microscopy(TEM)and x-ray diffraction(XRD)measurements indicated the existence of predicted polycrystalline P-C_(3)N_(4) Ulins on the KC1(100)wafers.And the TEM and XRD measured lattice spacings well match the calculated data.展开更多
基金Supported by the Bairen Project of the Chinese Academy of Sciences.
文摘A double-potential-well model is proposed to describe the core-shell thickness-dependent photoluminescence peaks and energy relaxations in semiconductor quantum dots (QDs). The surface effect plays an important role in the formation of new states-polaronic states around the surface of QDs. The polaronic states formed emit light due to the strong interaction between the core state (confined state) and the surface state with an enhanced participation of the size effect.
基金Supported by the National Natural Science Foundation of China(No.2 0 1730 73)
文摘The emission and Fourier transformation infrared spectra of freshly prepared porous silicon(PS) and the silicon wafer were examined. Increasing temperature generally led to a decrease in the emission intensities of the PS samples, however, the freshly prepared sample showed an unusually large and sudden increase in its emission intensity at the specific temperature at which the hydrogen ion conductivity in the silicon wafer increased. The O-H vibrations of the silicon wafer also showed a sudden decrease at the same temperature. These results are consistent with the assumption that the luminescence of fresh PS comes from the carrier bound exciton in its confined nanostructure.
基金Supported by the Beijing Synchrotron Radiation Laboratory,Institute of High Energy Physics,Chinese Academy of Sciences.
文摘The structure and physical properties of carbon nanotubes have been investigated by using in situ high pressure energy dispersive x-ray diffraction with synchrotron radiation at pressures up to 50.7 GPa.At atmospheric pressure,the structure of carbon nanotubes is similar to the hexagonal close-packed lattice of graphite with the interplanar spacing of the diffraction line(002)d002=0.3404 nm and that of the line(100)d100=0.2116 nm.According to the high pressure x-ray diffraction results,the diffraction line(002)is broadened and weakened above 8 GPa,and carbon nanotubes become partly amorphous.When the pressures of 10 and 20 GPa are decreased down to zero,the diffraction line(002)is partly recovered.While at the maximum pressure of 50.7 GPa,they entirely become amorphous and this amorphous transition is irreversible.We used the equation of state of Birch-Murnaghan to fit the P-V data of carbon nanotubes and obtained the bulk modulus K0=54.3±3.2 GPa(at K'0=4.0).
文摘Twelve new features from our Raman measurements of C_(70) have been observed by using the silver surface enhanced Raman scattering substrate with very high enhanced factor and highly sensitive Raman set.The results and discussion in this letter would make new knowledge to vibration modes of C_(70).The experimental data of the study confirm the validity of Jishi's calculation with a small error.
文摘The carbon-nitride thin films were deposited on the(100)oriented single-crystai KC1 wafers at ambient temperatures by using rf-plasma sputtering.The IR spectrum showed that the Ulins contained carbqn-nitnde bonds.The transmission electron microscopy(TEM)and x-ray diffraction(XRD)measurements indicated the existence of predicted polycrystalline P-C_(3)N_(4) Ulins on the KC1(100)wafers.And the TEM and XRD measured lattice spacings well match the calculated data.
