The femtosecond optical trapping capability and the effect of femtosecond laser pulses on cell viability were studied.The maximum lateral velocity at which the particles just failed to be trapped,together with the mea...The femtosecond optical trapping capability and the effect of femtosecond laser pulses on cell viability were studied.The maximum lateral velocity at which the particles just failed to be trapped,together with the measured average trapping power,were used to calculate the lateral trapping force(Q-value) .The viability of the cells after femtosecond laser trapping was ascertained by vital staining.Measurement of the Q-values shows that femtosecond optical tweezers are just as effective as continuous wave optical tweezers.The experiments demonstrate that there is a critical limit for exposure time at each corresponding laser power of femtosecond optical tweezers,and femtosecond laser tweezers are safe for optical trapping at low power with short exposure time.展开更多
Band engineering based on the construction of solid solutions is an effective approach to enhance the efficiency of semiconductor photocatalysts, via which the balance between light absorption and driving force can be...Band engineering based on the construction of solid solutions is an effective approach to enhance the efficiency of semiconductor photocatalysts, via which the balance between light absorption and driving force can be well achieved by continuously tuning the band structure. Here the ZnS1–xSex nanobelt solid solutions have been prepared via thermal treatment of ZnS1–xSex(en)0.5 precursors. The compositions are adjusted by changing the mole ratio of Se to S powder in the starting materials, resulting in continuously modulating the alignment of energy levels of the obtained solid solutions. The band structure is also studied via theoretical calculation. Accordingly, the light harvesting can be tuned too, as confirmed by the UV-vis absorption spectra. XPS valence spectra are used to determine the valence band maximum. Transient photoluminescence spectra are employed to study the separation of photogenerated charge carriers. BET specific surface area and CO2 adsorption isotherms of different catalysts are measured. The obtained ZnS1–xSex nanobelts exhibit different photocatalytic activity for solar-fuel production, dependent on many factors like the light harvesting and alignment of energy levels. The related mechanism is studied in detail.展开更多
Using the single particle theory and the non-flexibility collision model of electron and photon, the influence of the uncaptured electrons on the energy conversion efficiency of multi-photon nonlinear Compton scatteri...Using the single particle theory and the non-flexibility collision model of electron and photon, the influence of the uncaptured electrons on the energy conversion efficiency of multi-photon nonlinear Compton scattering in the extra stationary laser-plasma is investigated. It shows that in extra stationary laser-plasma,the uncaptured electrons make the Δω of the scattering frequency of the multi-photon Compton fall down with the increases of the incident radiation electron speed,the materials of the incident collision of electron and photon, and the number of the photons which work with the electrons at the same time. Under the modulation of the uncaptured electrons to the laser field, the energy conversion efficiency between electrons and photons will fall down with the increase of the electron incident radiation speed, using the low-power electrons for incident source, the loss can be efficiently reduced.展开更多
Geometrical light trapping is a simple and prom- ising strategy to largely improve the optical absorption and efficiency of solar cell. Nonetheless, implementation of geo- metrical light trapping in organic photovolta...Geometrical light trapping is a simple and prom- ising strategy to largely improve the optical absorption and efficiency of solar cell. Nonetheless, implementation of geo- metrical light trapping in organic photovoltaic is challenging due to the fact that uniform organic active layer can rarely be achieved on textured substrate. In this work, squarely ordered nanobowl array （SONA） is reported for the first time and [6,6]- phenyl-C6rbutyric acid methyl ester （PCBM）：poly（3-hexyl- thiophene） （P3HT）-based organic photovoltaic （OPV） device on SONA demonstrated over 28 % enhancement in power conversion efficiency over the planar counterpart. Interestingly, finite-difference time-domain （FDTD） optical simulation revealed that the superior light trapping by SONA originated from optical concentrator effect by nanobowl. Furthermore, aiming at low-cost, solution processible, and resource sus- tainable flexible solar cells, we employed Ag nanowires for the top transparent conducting electrode. This work not only revealed the in-depth understanding of light trapping by nanobowl optical concentrator, but also demonstrated the fea- sibility of implementing geometrical light trapping in OPV.展开更多
基金Supported by China Postdoctoral Science Foundation (No.20080440097)
文摘The femtosecond optical trapping capability and the effect of femtosecond laser pulses on cell viability were studied.The maximum lateral velocity at which the particles just failed to be trapped,together with the measured average trapping power,were used to calculate the lateral trapping force(Q-value) .The viability of the cells after femtosecond laser trapping was ascertained by vital staining.Measurement of the Q-values shows that femtosecond optical tweezers are just as effective as continuous wave optical tweezers.The experiments demonstrate that there is a critical limit for exposure time at each corresponding laser power of femtosecond optical tweezers,and femtosecond laser tweezers are safe for optical trapping at low power with short exposure time.
文摘Band engineering based on the construction of solid solutions is an effective approach to enhance the efficiency of semiconductor photocatalysts, via which the balance between light absorption and driving force can be well achieved by continuously tuning the band structure. Here the ZnS1–xSex nanobelt solid solutions have been prepared via thermal treatment of ZnS1–xSex(en)0.5 precursors. The compositions are adjusted by changing the mole ratio of Se to S powder in the starting materials, resulting in continuously modulating the alignment of energy levels of the obtained solid solutions. The band structure is also studied via theoretical calculation. Accordingly, the light harvesting can be tuned too, as confirmed by the UV-vis absorption spectra. XPS valence spectra are used to determine the valence band maximum. Transient photoluminescence spectra are employed to study the separation of photogenerated charge carriers. BET specific surface area and CO2 adsorption isotherms of different catalysts are measured. The obtained ZnS1–xSex nanobelts exhibit different photocatalytic activity for solar-fuel production, dependent on many factors like the light harvesting and alignment of energy levels. The related mechanism is studied in detail.
文摘Using the single particle theory and the non-flexibility collision model of electron and photon, the influence of the uncaptured electrons on the energy conversion efficiency of multi-photon nonlinear Compton scattering in the extra stationary laser-plasma is investigated. It shows that in extra stationary laser-plasma,the uncaptured electrons make the Δω of the scattering frequency of the multi-photon Compton fall down with the increases of the incident radiation electron speed,the materials of the incident collision of electron and photon, and the number of the photons which work with the electrons at the same time. Under the modulation of the uncaptured electrons to the laser field, the energy conversion efficiency between electrons and photons will fall down with the increase of the electron incident radiation speed, using the low-power electrons for incident source, the loss can be efficiently reduced.
基金supported by the HK-RGCGeneral Research Funds(HKUST 605710,604809,612111,612113)partially supported by ITS/117/13 from Hong Kong Innovation Technology Commission
文摘Geometrical light trapping is a simple and prom- ising strategy to largely improve the optical absorption and efficiency of solar cell. Nonetheless, implementation of geo- metrical light trapping in organic photovoltaic is challenging due to the fact that uniform organic active layer can rarely be achieved on textured substrate. In this work, squarely ordered nanobowl array （SONA） is reported for the first time and [6,6]- phenyl-C6rbutyric acid methyl ester （PCBM）：poly（3-hexyl- thiophene） （P3HT）-based organic photovoltaic （OPV） device on SONA demonstrated over 28 % enhancement in power conversion efficiency over the planar counterpart. Interestingly, finite-difference time-domain （FDTD） optical simulation revealed that the superior light trapping by SONA originated from optical concentrator effect by nanobowl. Furthermore, aiming at low-cost, solution processible, and resource sus- tainable flexible solar cells, we employed Ag nanowires for the top transparent conducting electrode. This work not only revealed the in-depth understanding of light trapping by nanobowl optical concentrator, but also demonstrated the fea- sibility of implementing geometrical light trapping in OPV.
