CAJ | 학술논문

研发的超快电子衍射系统由超快电子枪、样品室、超快读出系统、电源系统,以及真空系统等组成,该超快电子衍射系统具有较高的时间分辩能力和较强的探测能力.光电阴极是蒸镀于MgFB2窗上的35 nm的银膜,该阴极对266 nm的紫外光比较敏感,有较高的量子效率,又具有很好的化学稳定性.用短磁聚焦系统来实现对光电子的聚焦,有两对偏转板,其中的一对在测量时间脉宽时用作扫描板.用双MCP探测器来增强电子图像的强度,其增益在104以上,具有单电子探测能力.系统的总时间脉宽设计为358 fs.
연발적초쾌전자연사계통유초쾌전자창、양품실、초쾌독출계통、전원계통,이급진공계통등조성,해초쾌전자연사계통구유교고적시간분변능력화교강적탐측능력.광전음겁시증도우MgFB2창상적35 nm적은막,해음겁대266 nm적자외광비교민감,유교고적양자효솔,우구유흔호적화학은정성.용단자취초계통래실현대광전자적취초,유량대편전판,기중적일대재측량시간맥관시용작소묘판.용쌍MCP탐측기래증강전자도상적강도,기증익재104이상,구유단전자탐측능력.계통적총시간맥관설계위358 fs.
The designed electron diffraction system consists of an ultra-fast electron gun,a sample chamber,a readout system,a power supply system,and a vacuum system,and it bears such unique characteristics as high energy,high temporal resolution,and high detection capacity.The photocathode is of a 35 nm Ag film deposited on an MgF2 glass disk,and it is sensitive to ultraviolet light with wavelength of 266 nm.A magnetic lens is used to focus the electrons.Two pairs of electric deflection plates are used in the X and Y directions respectively to control the movement of the electrons,and one pair of them will act as a scanning plate while measuring the pulse width of electrons.The sample chamber is made of stainless steel,and in the middle of the chamber there is a specimen holder,capable of shifting in three dimensions and turning around its axis.The diffraction pattern recording system has a very high detecting efficiency,and even a single electron could be detected.A cascade MCP detector is used to ensure an electron gain reached to 104.The electron gun is in a vacuum system of 10-4 Pa.The whole gun is shielded by a μ-metal sheath.The designed temporal resolution of the ultra-fast electron diffraction system (UED) is about 358 fs.