The phenomenon of secondary electron emission is of considerable interest in areas such as particle accelerators and on-board radio frequency(RF) components.Total secondary electron yield(TSEY) is a parameter that is ...The phenomenon of secondary electron emission is of considerable interest in areas such as particle accelerators and on-board radio frequency(RF) components.Total secondary electron yield(TSEY) is a parameter that is frequently used to describe the secondary electron emission capability of a material.It has been widely recognized that the TSEY vs.primary electron energy curve has a single-hump shape.However, the TSEY–energy curve with a double-hump shape was also observed experimentally-this anomaly still lacks explanation.In this work, we explain this anomaly with the help of a millimetre-scale(mm-scale) silver pillar array fabricated by three-dimensional(3 D) printing technology.The TSEY–energy curve of this pillar array as well as its flat counterpart is obtained using sample current method.The measurement results show that for the considered primary electron energy(40–1500 eV), the pillar array can obviously suppress TSEY,and its TSEY–energy curve has an obvious double-hump shape.Through Monte Carlo simulations and electron beam spot size measurements, we successfully attribute the double-hump effect to the dependence of electron beam spot size on the primary electron energy.The observations of this work may be of help in determining the TSEY of roughened surface with characteristic surface structures comparable to electron beam spot size.It also experimentally confirms the TSEY suppression effect of pillar arrays.展开更多
The total electron yield （TEY） mode has been developed successfully for XANES measurements at Beamline 4BTA of BSRF （Beijing Synchrotron Radiation Facility）. Its performance was studied by measuring sulphur K-edge...The total electron yield （TEY） mode has been developed successfully for XANES measurements at Beamline 4BTA of BSRF （Beijing Synchrotron Radiation Facility）. Its performance was studied by measuring sulphur K-edge XANES of three CdS samples （mixed with graphite powder as an electric conductor） with different concentration： 75%, 50~ and 25%. The data are collected in TEY mode and fluorescence yield （FY） mode respectively for comparison. The results demonstrate that the TEY spectra of three samples agree well with each other after the background is subtracted and normalized. The measured XANES spectra by TEY mode without bias and with 100V bias are almost identical to one another, but the signal-to-noise ratio of spectra measured without bias is better than that with 100V bias. The consistency of the self-absorption corrected FY spectra and TEY spectra are within 10% for the three samples.展开更多
The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000...The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000),for studying properties of solid, liquid, gas, film and other forms of materials at sub-micron scale. In this paper,we present a review on newly implemented techniques, such as total electron yield(TEY), dual energy contrast imaging, nano-CT, soft X-ray excited optical luminance(SXEOL), and coherent diffraction imaging(CDI)under development. Several research cases in nanomaterials, environmental science and biology are presented to demonstrate capabilities of the beamline.展开更多
It is demonstrated that two kinds of soft X-ray spectroscopy are useful as nondestructive methods to in- vestigate multilayer structures modified by interdiffusion or by chemical reaction of adjoining layers in depth ...It is demonstrated that two kinds of soft X-ray spectroscopy are useful as nondestructive methods to in- vestigate multilayer structures modified by interdiffusion or by chemical reaction of adjoining layers in depth direc- tion. One is the total electron yield (TEY) spectroscopy involving angular dependence measurement. Using this method, it was found that in LiF/Si/LiF trilayers, the Si layers exhibited a characteristic similar to porous Si, and in CaF2/Si/CaF2 trilayers, it was found that CaF2 segregated through the Si layer. Moreover, it has been shown that the thickness of the top layer of a Mo/Si X-ray multilayer can be determined by analyzing TEY signals generated by the standing wave. The other is the soft X-ray emission spectroscopy involving spectral shape analysis. Using this method, it was found that in Mo/Si X-ray multilayers, the interdiffusion or chemical reaction giving rise to deterioration of re- flectance character occurs in as-deposited samples as well as in heated samples. In antiferromagnetic Fe/Si multilay- ers, it was confirmed that there was no existence of pure Si layers, but insulating FeSi2 layers were present. This result suggests that the source of antiferromagnetic coupling is not conduction electrons but quantum wave interference.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1832190,61501364,U1537211,and 11705142)
文摘The phenomenon of secondary electron emission is of considerable interest in areas such as particle accelerators and on-board radio frequency(RF) components.Total secondary electron yield(TSEY) is a parameter that is frequently used to describe the secondary electron emission capability of a material.It has been widely recognized that the TSEY vs.primary electron energy curve has a single-hump shape.However, the TSEY–energy curve with a double-hump shape was also observed experimentally-this anomaly still lacks explanation.In this work, we explain this anomaly with the help of a millimetre-scale(mm-scale) silver pillar array fabricated by three-dimensional(3 D) printing technology.The TSEY–energy curve of this pillar array as well as its flat counterpart is obtained using sample current method.The measurement results show that for the considered primary electron energy(40–1500 eV), the pillar array can obviously suppress TSEY,and its TSEY–energy curve has an obvious double-hump shape.Through Monte Carlo simulations and electron beam spot size measurements, we successfully attribute the double-hump effect to the dependence of electron beam spot size on the primary electron energy.The observations of this work may be of help in determining the TSEY of roughened surface with characteristic surface structures comparable to electron beam spot size.It also experimentally confirms the TSEY suppression effect of pillar arrays.
基金Supported by National Natural Science Foundation of China (10775150)
文摘The total electron yield （TEY） mode has been developed successfully for XANES measurements at Beamline 4BTA of BSRF （Beijing Synchrotron Radiation Facility）. Its performance was studied by measuring sulphur K-edge XANES of three CdS samples （mixed with graphite powder as an electric conductor） with different concentration： 75%, 50~ and 25%. The data are collected in TEY mode and fluorescence yield （FY） mode respectively for comparison. The results demonstrate that the TEY spectra of three samples agree well with each other after the background is subtracted and normalized. The measured XANES spectra by TEY mode without bias and with 100V bias are almost identical to one another, but the signal-to-noise ratio of spectra measured without bias is better than that with 100V bias. The consistency of the self-absorption corrected FY spectra and TEY spectra are within 10% for the three samples.
基金Supported by National Natural Science Foundation of China(Nos.11079050,11290165,11305252 and 11205232)Programs of the Chinese Academy of Sciences(Nos.KJCX2-EW-W09 and KJZD-EW-M03)+2 种基金the Open Research Project of the Large Scientific Facility of the Chinese Academy of Sciences:Study on Self-assembly Technology and Nanometer Array with Ultra-high Densitythe National Natural Science Foundation for Outstanding Young Scientists(No.11225527)the Shanghai Academic Leadership Program(No.13XD1404400)
文摘The BL08U1 A beamline is established as a sophisticated platform at Shanghai Synchrotron Radiation Facility(SSRF), taking advantage of its high spatial resolution(< 30 nm) and high energy resolving power(>10 000),for studying properties of solid, liquid, gas, film and other forms of materials at sub-micron scale. In this paper,we present a review on newly implemented techniques, such as total electron yield(TEY), dual energy contrast imaging, nano-CT, soft X-ray excited optical luminance(SXEOL), and coherent diffraction imaging(CDI)under development. Several research cases in nanomaterials, environmental science and biology are presented to demonstrate capabilities of the beamline.
文摘It is demonstrated that two kinds of soft X-ray spectroscopy are useful as nondestructive methods to in- vestigate multilayer structures modified by interdiffusion or by chemical reaction of adjoining layers in depth direc- tion. One is the total electron yield (TEY) spectroscopy involving angular dependence measurement. Using this method, it was found that in LiF/Si/LiF trilayers, the Si layers exhibited a characteristic similar to porous Si, and in CaF2/Si/CaF2 trilayers, it was found that CaF2 segregated through the Si layer. Moreover, it has been shown that the thickness of the top layer of a Mo/Si X-ray multilayer can be determined by analyzing TEY signals generated by the standing wave. The other is the soft X-ray emission spectroscopy involving spectral shape analysis. Using this method, it was found that in Mo/Si X-ray multilayers, the interdiffusion or chemical reaction giving rise to deterioration of re- flectance character occurs in as-deposited samples as well as in heated samples. In antiferromagnetic Fe/Si multilay- ers, it was confirmed that there was no existence of pure Si layers, but insulating FeSi2 layers were present. This result suggests that the source of antiferromagnetic coupling is not conduction electrons but quantum wave interference.
