Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the ...Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental展开更多
The constant photocurrent method in the ac-mode （ac-CPM） is used to determine the defect density of states （DOS） in hydrogenated microcrystalline silicon （μc-Si：H） prepared by very high frequency plasma-enhanc...The constant photocurrent method in the ac-mode （ac-CPM） is used to determine the defect density of states （DOS） in hydrogenated microcrystalline silicon （μc-Si：H） prepared by very high frequency plasma-enhanced chemical vapor deposition （VHF-PECVD）. The absorption coefficient spectrum （ac-α （h v））, is measured under ac- CPM conditions at 60 Hz. The measured ac-α（hv） is converted by the CPM spectroscopy into a DOS distribution covering a portion in the lower energy range of occupied states. We have found that the density of valence band- tail states falls exponentially towards the gap with a typical band-tail width of 63 meV. Independently, computer simulations of the ac-CPM are developed using a DOS model that is consistent with the measured ac-α（hv） in the present work and a previously measured transient photocurrent （TPC） for the same material. The DOS distribution model suggested by the measurements in the lower and in the upper part of the energy-gap, as well as by the numerical modelling in the middle part of the energy-gap, coincide reasonably well with the real DOS distribution in hydrogenated microcrystalline silicon because the computed ac-α（h v） is found to agree satisfactorily with the measured ac-α （h v）.展开更多
Local radiative density of optical states （LDOS） offers a tool to control the radiative rate of spontaneous emission from molecules, atoms, and quan- tum dots, which is proportional to LDOS. This paper presents that...Local radiative density of optical states （LDOS） offers a tool to control the radiative rate of spontaneous emission from molecules, atoms, and quan- tum dots, which is proportional to LDOS. This paper presents that LDOS how to make the population of excited-state decay exponentially in time, and how these dynamics can be affected. By adopting the plane-wave expansion method, properties of an inverse-opal photonic crystal are studied with the help of photonic dispersion relations. Results in this paper show that the LDOS is radically modified in photonic crystal, and the rate of spontaneous emission can be described by the functions of position in the crystal and orientation of transition dipole moment.展开更多
文摘Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental
文摘The constant photocurrent method in the ac-mode （ac-CPM） is used to determine the defect density of states （DOS） in hydrogenated microcrystalline silicon （μc-Si：H） prepared by very high frequency plasma-enhanced chemical vapor deposition （VHF-PECVD）. The absorption coefficient spectrum （ac-α （h v））, is measured under ac- CPM conditions at 60 Hz. The measured ac-α（hv） is converted by the CPM spectroscopy into a DOS distribution covering a portion in the lower energy range of occupied states. We have found that the density of valence band- tail states falls exponentially towards the gap with a typical band-tail width of 63 meV. Independently, computer simulations of the ac-CPM are developed using a DOS model that is consistent with the measured ac-α（hv） in the present work and a previously measured transient photocurrent （TPC） for the same material. The DOS distribution model suggested by the measurements in the lower and in the upper part of the energy-gap, as well as by the numerical modelling in the middle part of the energy-gap, coincide reasonably well with the real DOS distribution in hydrogenated microcrystalline silicon because the computed ac-α（h v） is found to agree satisfactorily with the measured ac-α （h v）.
文摘Local radiative density of optical states （LDOS） offers a tool to control the radiative rate of spontaneous emission from molecules, atoms, and quan- tum dots, which is proportional to LDOS. This paper presents that LDOS how to make the population of excited-state decay exponentially in time, and how these dynamics can be affected. By adopting the plane-wave expansion method, properties of an inverse-opal photonic crystal are studied with the help of photonic dispersion relations. Results in this paper show that the LDOS is radically modified in photonic crystal, and the rate of spontaneous emission can be described by the functions of position in the crystal and orientation of transition dipole moment.
