Lack of proportionality of total electron yield and soft x-ray absorption coefficient
Lack of proportionality of total electron yield and soft x-ray absorption coefficient
复制标题
总电子产额与软X射线吸收系数不成比例
DOI：
10.1063/1.371854
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发表时间：
2000
影响因子：
3.2
通讯作者：
G. Ulm
中科院分区：
文献类型：
--
作者：
H. Henneken;F. Scholze;G. Ulm
对于许多应用，总电子产额(TEY) η被假定成正比的乘积的线性吸收系数和光子能量。为了验证该模型，我们在光子能量为50 ~ 1500 eV的单晶（111）表面测量了铜和金的总电子产率，相对不确定度小于3.6%。此外，通过测量覆盖薄金层或薄铜层的聚酰亚胺薄膜的透光率，改进了吸收系数的数据。实验是在德国联邦物理技术大学的辐射测量实验室进行的，该实验室位于电子存储环BESSY i。对于光子能量低于150 eV，如果考虑到这里通过测量TEY作为辐射入射角的函数来确定的饱和效应，则总电子产率与吸收系数成正比。在较高的光子能量下，TEY与吸收系数与光子能量的乘积之比连续下降约30%，直至1500 eV。我们提出了一个新的描述初级电子和次级电子贡献的总电子产率的解析模型。输入参数，如电子逃逸深度和软x射线的反射已被实验确定。当使用这些参数时，当调整唯一的自由参数，即吸收的光子能量转化为二次电子的效率时，我们的模型与测量的TEY具有很好的一致性。
For many applications, the total electron yield (TEY) η is assumed to be proportional to the product of the linear absorption coefficient and the photon energy. To test this model we measured the total electron yield of copper and gold at the (111) surface of single crystals in the photon energy range between 50 eV and 1500 eV with relative uncertainties lower than 3.6%. In addition, the data for the absorption coefficient were improved by measuring the transmittance of polyimide films covered either with thin gold or copper layers. The experiments were performed at the radiometry laboratory of the Physikalisch-Technische Bundesanstalt at the electron storage ring BESSY I. For photon energies below 150 eV, the total electron yield is proportional to the absorption coefficient, provided the saturation effects as determined here, by measurements of the TEY as a function of the angle of incidence of the radiation, are taken into account. At higher photon energy, the ratio between the TEY and the product of absorption coefficient times the photon energy decreases continuously by about 30% down to 1500 eV. We present a new analytical model for the total electron yield describing the contributions of primary and secondary electrons. Input parameters such as the electron escape depth and the reflection of the soft x-rays has been experimentally determined. When these parameters are used, our model achieves good agreement with the measured TEY, when the only free parameter, i.e., the efficiency with which the absorbed photon energy is converted into secondary electrons, is adjusted.