The dynamic characteristics of ground soil using micro-tremor observation in Asia (Zushi and Ogasawara (Japan), Xi’an (China), Manila (Philippines), and Gujarat (India)) are studied. Ground micro-tremor signals were ...The dynamic characteristics of ground soil using micro-tremor observation in Asia (Zushi and Ogasawara (Japan), Xi’an (China), Manila (Philippines), and Gujarat (India)) are studied. Ground micro-tremor signals were observed and analyzed by fast Fourier transform method (FFT). The response of ground soil to frequency of ground micro-tremor is revealed, and func- tions with frequency-dependence and frequency-selection of micro-tremor for different foundation soil strata are also researched. The horizontal to vertical spectral ratio (H/V, Nakamura technique) of micro-tremor observed at the surface ground was used to evaluate the site’s predominant period. This paper also discusses the application of micro-tremor on site safety evaluation, and gives the observed calculation results obtained at multiple points. The experimental foundation and the deduction process of the method are described in detail. Some problems of the method are pointed out. Potential use of the technique’s good expandable nature makes it a useable means for preventing and reducing disaster’s harmful effects.展开更多
Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of p...Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.展开更多
文摘The dynamic characteristics of ground soil using micro-tremor observation in Asia (Zushi and Ogasawara (Japan), Xi’an (China), Manila (Philippines), and Gujarat (India)) are studied. Ground micro-tremor signals were observed and analyzed by fast Fourier transform method (FFT). The response of ground soil to frequency of ground micro-tremor is revealed, and func- tions with frequency-dependence and frequency-selection of micro-tremor for different foundation soil strata are also researched. The horizontal to vertical spectral ratio (H/V, Nakamura technique) of micro-tremor observed at the surface ground was used to evaluate the site’s predominant period. This paper also discusses the application of micro-tremor on site safety evaluation, and gives the observed calculation results obtained at multiple points. The experimental foundation and the deduction process of the method are described in detail. Some problems of the method are pointed out. Potential use of the technique’s good expandable nature makes it a useable means for preventing and reducing disaster’s harmful effects.
基金the National Key Research and Development Program of China(2017YFA0204800)the National Natural Science Foundation of China(21833009,21533010,and 21525315)+2 种基金the Scientific Instrument Developing Project of the Chinese Academy of Sciences(YJKYYQ20190003)Liaoning Revitalization Talents Program(XLYC1802126)Dalian City Foundation for Science and Technology Innovation(2019J12GX031).
文摘Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.
