多碱阴极光电发射理论研究  

Photoemission Theory of Multi Alkali Cathode

作　　者：李晓峰[1,2] 冯刘 陆强[1] 

机构地区：[1]北方夜视技术股份有限公司,昆明650114 [2]微光夜视技术重点实验室,西安710065

出　　处：《光子学报》2013年第10期1176-1181,共6页Acta Photonica Sinica

基　　金：微光夜视技术重点实验室基金(No.J2011016)资助

摘　　要：测量了未经Cs-Sb激活的Na2KSb膜层和经过Cs-Sb激活的Na2KSb(Cs)膜层的光谱反射率.测量结果表明:两种膜层在200～700nm波长范围内光谱反射率基本相同,因此可以推断出这两种膜层的折射率也基本相同,说明经过表面Cs-Sb激活的Na2KSb(Cs)膜层内部的成份基本未发生变化,两种膜层的光程差基本相同;推断出Na2KSb膜层表面的Cs-Sb层很薄,其表面激活过程是一种表面效应.对Na2KSb(Cs)多碱阴极膜层进行了XPS能谱分析,测量结果表明Na2KSb(Cs)多碱阴极膜层表面除主要存在Na、K和Sb三种元素之外,还存在C、O以及少量的Cs元素;Na2KSb(Cs)多碱阴极膜层表面存在C和O的原因是在样品解封的过程中受到了污染.对Na2KSb(Cs)多碱阴极膜层表面进行时间为10s的氩离子刻蚀,再进行XPS分析,结果表明能谱中不再出现Cs原子的谱峰.对Na2KSb(Cs)多碱阴极膜层表面进行总时间为600s的氩离子刻蚀,XPS能谱中出现了Si原子的谱峰,说明氩离子已经刻蚀到阴极玻璃窗的表面.根据刻蚀时间分析,Na2KSb(Cs)多碱阴极膜层表面存在的Cs原子层的厚度约为3nm,并且该Cs原子层只是存在于多碱阴极膜层的表面,并未深入到多碱阴极的膜层内部,这也说明Na2KSb膜层的表面Cs激活是一种表面效应.测量了未经过Cs-Sb激活和经过Cs-Sb激活的两种多碱阴极样品的荧光谱,测量结果表明:经Cs-Sb激活的多碱阴极样品与未经过Cs-Sb激活的多碱阴极样品相比,其荧光谱的峰值强度有所增加,而荧光谱的峰值波长却有所减小.说明Na2KSb多碱阴极在Cs-Sb激活之后,跃迁电子的数量有所增加,同时跃迁电子的能级也有所提高,这种现象可以解释为多碱阴极在激活过程中的"体积"效应.所以多碱阴极在表面Cs激活过程中,既有表面效应,又有"体积"效应,而这种"体积"效应是指Na2KSb膜层内部的能带结构变化,并非Cs原子扩散到Na2KSb膜层内部.The spectral reflectivities of Na2KSb film both with and without the activation layer of Cs-Sb were measured.The measurement results show that the spectral reflectivity of these two films within the wavelength range of 200 ～ 700 nm are substantially the same.So it can be inferred that the refractive index of both films are also substantially the same,and both films are substantially no change in its internal constituent.Because the spectral reflectivity is not changed,and the optical path difference of the two films are substantially the same,it can be inferred that the Cs-Sb layer was coated on the surface of Na2KSb,so the activation process of Na2KSb surface is a surface effect.In addition,Na2KSb （Cs） multi-alkali cathode film was analysis by XPS,the results showed that three elements was existed mainly in addition to Na,K,and Sb,but also the presence of CO2 and a small amount of Cs elements.The reason of the presence of C and O on the surface of Na2KSb （Cs） is oxidation in the unsealed process of sample.After 10 second time of argon ion etching,Na2KSb （Cs） multi-alkali cathode film was analyzed by XPS,the results show that the energy spectrum of Cs atoms has disappeared.When continued for 600 seconds time of the argon ion etching,on Na2KSb （Cs） multi-alkali cathode film surface,the spectrum of the Si atoms in XPS spectroscopy was appeared.This showed that argon ion has already etched to the glass window surface.According to the etching time analysis,the thickness of the multi-alkali cathode film surface Na2KSb （Cs） of Cs atomic layers approximately 3nm,and the Cs atomic layer exists only in the surface of the multi-alkali cathode layer,No deep into the multi-alkali cathode film inside.The fluorescence spectrum of multi-alkali cathode with the Cs-Sb activation and without Cs-Sb activation has been measured.The measurement results showed that the peak wavelength of fluorescence spectrum of sample with Cs activation has shifted toward to short directions,while peak intensity of samples with

关 键 词：多碱阴极 像增强器 光电发射 电子跃迁 量子效率 

分 类 号：O462.3[理学—电子物理学]