Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described ...Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described a laser dispersion method applied in the apparatus combining the high-n H atom Rydberg tagging time-of-flight technique with the vacuum ultraviolet free electron laser(VUV FEL).The Lyman-αlaser beam(121.6 nm)used in the H-atom detection was generated by the difference frequency four-wave mixing schemes in a Kr/Ar gas cell.After passing through an off-axis biconvex LiF lens,the 121.6 nm beam was dispersed from the 212.6 nm and 845 nm beams due to the different deflection angles experienced by these laser beams at the surfaces of the biconvex lens.This method can eliminate the background signal from the 212.6 nm photolysis.Combined with the VUV FEL,photodissociation of H2S at 122.95 nm was studied successfully.The TOF spectrum was measured and the derived total kinetic energy release spectrum was displayed.The results suggest that the experimental setup is a powerful tool for investigating photodissociation dynamics of molecules in the VUV region which involves the H-atom elimination processes.展开更多
Femtosecond pulsed lasers have been widely used over the past decades due to their capability to fabricate precise patterns at the micro-and nano-lengths scales. A key issue for efficient material processing is the de...Femtosecond pulsed lasers have been widely used over the past decades due to their capability to fabricate precise patterns at the micro-and nano-lengths scales. A key issue for efficient material processing is the determination of the laser parameters used in the experimental set ups. Despite a systematic investigation that has been performed to highlight the impact of every parameter independently, little attention has been drawn on the role of the substrate material on which the irradiated solid is placed. In this work, the influence of the substrate is emphasised for films of various thicknesses, which demonstrates that both the optical and thermophysical properties of the substrate affect the thermal fingerprint on the irradiated film while the impact is manifested to be higher at smaller film sizes. Two representative materials, silicon and fused silica, have been selected as typical substrates for thin films(gold and nickel) of different optical and thermophysical behaviour and the thermal response and damage thresholds are evaluated for the irradiated solids. The pronounced influence of the substrate is aimed to pave the way for new and more optimised designs of laserbased fabrication set ups and processing schemes.展开更多
Our dynamic laser light scattering(LLS) study shows that the current widely used protocols of dissolving amyloidogenic protein/peptide do not really result in a true solution;namely,there always exist a trace amount o...Our dynamic laser light scattering(LLS) study shows that the current widely used protocols of dissolving amyloidogenic protein/peptide do not really result in a true solution;namely,there always exist a trace amount of interchain aggregates,which greatly affect the association kinetics,partially explaining why different kinetics were reported even for a solution with identical protein and solvent.Recently,using a combination of the conventional dissolution procedure and our newly developed ultra-filtration method,we have developed a novel protocol to prepare a true solution of amyloidogenic protein/peptide without any interchain aggregates.The resultant solutions remain in their monomeric state for at least one week,which is vitally important for further study of the very initial stage of the interchain association under the physiological conditions because more and more evidence suggests that it is those small oligomers rather than large fabric aggregates that are cytotoxic.In addition,this study shows that combining static and dynamic LLS can lead to more physical and microscopic information about the protein association instead of only the size distribution.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB17000000)the National Natural Science Foundation of China (NSFC Center for Chemical Dynamics (No.21688102)+4 种基金the National Natural Science Foundation of China (No.21673232, No.21873099, No.21922306)the International Partnership Program of Chinese Academy of Sci-ences (No.121421KYSB20170012)supported by the National Natural Science Foundation of China (No.21973010)supported by the National Natural Science Foundation of China (No.21773236)supported by the Natural Science Research Project of Education Department of Anhui Province (No.KJ2019A0521).
文摘Photodissociation of H2S in the VUV region plays an important role in the atmospheric chemistry and interstellar chemistry.To date,however,few studies have been focused on this topic.In this article,we have described a laser dispersion method applied in the apparatus combining the high-n H atom Rydberg tagging time-of-flight technique with the vacuum ultraviolet free electron laser(VUV FEL).The Lyman-αlaser beam(121.6 nm)used in the H-atom detection was generated by the difference frequency four-wave mixing schemes in a Kr/Ar gas cell.After passing through an off-axis biconvex LiF lens,the 121.6 nm beam was dispersed from the 212.6 nm and 845 nm beams due to the different deflection angles experienced by these laser beams at the surfaces of the biconvex lens.This method can eliminate the background signal from the 212.6 nm photolysis.Combined with the VUV FEL,photodissociation of H2S at 122.95 nm was studied successfully.The TOF spectrum was measured and the derived total kinetic energy release spectrum was displayed.The results suggest that the experimental setup is a powerful tool for investigating photodissociation dynamics of molecules in the VUV region which involves the H-atom elimination processes.
基金Projects(862016(Bio Combs4Nanofibres)HELLAS-CH+1 种基金MIS 5002735) funded by the Operational Programme “Competitiveness, Entrepreneurship and Innovation” and co-financed by Greece and the EU (European Regional Development Fund)Project (COST Action TUMIEE) supported by COST-European Cooperation in Science and Technology。
文摘Femtosecond pulsed lasers have been widely used over the past decades due to their capability to fabricate precise patterns at the micro-and nano-lengths scales. A key issue for efficient material processing is the determination of the laser parameters used in the experimental set ups. Despite a systematic investigation that has been performed to highlight the impact of every parameter independently, little attention has been drawn on the role of the substrate material on which the irradiated solid is placed. In this work, the influence of the substrate is emphasised for films of various thicknesses, which demonstrates that both the optical and thermophysical properties of the substrate affect the thermal fingerprint on the irradiated film while the impact is manifested to be higher at smaller film sizes. Two representative materials, silicon and fused silica, have been selected as typical substrates for thin films(gold and nickel) of different optical and thermophysical behaviour and the thermal response and damage thresholds are evaluated for the irradiated solids. The pronounced influence of the substrate is aimed to pave the way for new and more optimised designs of laserbased fabrication set ups and processing schemes.
基金support of the National Natural Science Foundation of China Project(20934005)the Hong Kong Special Administration Region Earmarked Project(CUHK4046/08P,2160365+1 种基金CUHK4039/08P,2160361 CUHK4042/09P,2160396)
文摘Our dynamic laser light scattering(LLS) study shows that the current widely used protocols of dissolving amyloidogenic protein/peptide do not really result in a true solution;namely,there always exist a trace amount of interchain aggregates,which greatly affect the association kinetics,partially explaining why different kinetics were reported even for a solution with identical protein and solvent.Recently,using a combination of the conventional dissolution procedure and our newly developed ultra-filtration method,we have developed a novel protocol to prepare a true solution of amyloidogenic protein/peptide without any interchain aggregates.The resultant solutions remain in their monomeric state for at least one week,which is vitally important for further study of the very initial stage of the interchain association under the physiological conditions because more and more evidence suggests that it is those small oligomers rather than large fabric aggregates that are cytotoxic.In addition,this study shows that combining static and dynamic LLS can lead to more physical and microscopic information about the protein association instead of only the size distribution.
