Development of nm-scale soft-X-ray spectroscopy electron microscope and its application to BN materials

我们研制了一台用于透射电子显微镜的高能量分辨率软X射线光谱仪，用于从已识别的小样品区域获得价带(占位态)的态密度信息。通过使用两个线密度分别为1200和2400线/mm的VLS光栅，可以获得60 eV到1200 eV的能量范围。该探测器的尺寸为27.6×27.6 mm~2，相当于6.5×10~(-4)mm~(-4)的收集角度。通过引入X射线反射平面镜，光谱强度提高了2.2倍。因此，该光谱仪的有效收集角为1.4×10~(-3)。该光谱仪对Si L发射(~100 eV)、B K发射(~180 eV)和铜L发射(~930 eV)的能量分辨率分别为0.1、0.4和1.4 eV。该谱仪成功地获得了h、c、w-BN、α，βB、Si、碳同素异形体和准晶等全部样品的价带能级。新的光谱仪将在1000 eV时为我们提供约0.7 eV的能量分辨率

We have developed a high energy-resolution soft-X-ray spectrometer for a transmission electron microscope to obtain the information of the density of states(DOS)of the valence band (occupied states) from identified small specimen areasThe spectrometer was composed of varied-line-spacing(VLS)gratings and a CCD detector. An energy range from 60eV to 1200eV was accessible by using two VLS gratings, which have line densities of 1200 and 2400 lines/mm. the size of the CCD detector was 27.6x27.6mm2,which corresponds to a collection angle of 6.5x10.^<-4>sr. By introducing X-ray reflection flat mirrors, spectral intensity was improved by 2.2 times. Thus, the effective collection angle of the spectrometer was 1.4x10.^<-3>sr. Energy resolutions of this spectrometer for Si L-emission(〜100eV),B K-emission(〜180eV)and Cu L-emission(〜930eV)were evaluated to be 0.1,0.4 and 1.4eV, respectively.This spectrometer successfully obtained the DOS of the valence band from specified amall specimen areas of h,c,w-BN,α, βboron, Si, carbon allotropes and quasicrystalsWe have been designing a new VLS grating to improve the energy resolution with a help of another Grant-in-Aid for Scientific research(B). The new spectrometer will give us an energy resolution of about 0.7eV at 1000eV