In this study, the formation of Ag–S bond was systematically elucidated by thickness‐dependent ultraviolet photoelectron spectroscopy (UPS) in order to understand the L‐cysteine interaction with silver surface. A clean Ag(111) as the model system for silver surface was used, and L‐cysteine films on silver substrate were formed by vacuum evaporation. The orbital configurations at the interface was estimated including work function, secondary electron cutoff (SECO), highest occupied molecular orbital (HOMO) onset, position of an interface state, charge injection barrier, and ionization energy. A clear spectral feature was appeared in between Fermi edge and HOMO of L‐cysteine, and the feature can be attributed to the formation of Ag–S bonding. In the case of SECO, the maximum shift was 0.46 eV to the higher binding energy side at the nominal thickness of 1 Å. However, from the nominal thickness of 2 Å, SECO started to shift to the lower binding energy side, and at 16 Å, the SECO shifted to a value of around 0.4 eV to the lower binding energy side to almost cancel the initial vacuum level shift. This behavior can be attributed to weakening of the silver‐sulfur bond with increasing of L‐cysteine coverage referring to the literature. The photoelectron yield spectroscopy (PYS) was also performed as an additional spectroscopic work, which exhibited that the work function of silver once decreased and then recovered at low coverage. This behavior can also be assigned to a weakening the interaction of L‐cysteine with silver by increasing of L‐cysteine coverage.

中文翻译：

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L-半胱氨酸与银表面相互作用的光发射研究

在这项研究中，通过依赖于厚度的紫外光电子能谱（UPS）系统地阐明了Ag-S键的形成，以了解L-半胱氨酸与银表面的相互作用。使用干净的Ag（111）作为银表面的模型系统，并通过真空蒸发在银基板上形成L-半胱氨酸膜。估计界面处的轨道构型，包括功函，二次电子截止（SECO），最高占据分子轨道（HOMO）开始，界面态位置，电荷注入势垒和电离能。在Fermi边缘和L-半胱氨酸的HOMO之间出现了清晰的光谱特征，该特征可归因于Ag-S键的形成。对于SECO，最大偏移为0。在标称厚度为1Å时，到更高的结合能侧为46 eV。但是，SECO从标称厚度2Å开始向较低的结合能侧偏移，而在16Å时，SECO向较低的结合能侧偏移了约0.4 eV的值，几乎抵消了初始真空能级的偏移。 。这种现象可以归因于参考文献中随着L-半胱氨酸覆盖率的增加而使银-硫键减弱。还进行了光电子产率光谱（PYS）作为附加的光谱工作，显示出银的功函数一旦降低，然后在低覆盖率下恢复。这种行为也可以归因于通过增加L-半胱氨酸的覆盖范围来削弱L-半胱氨酸与银的相互作用。SECO开始向较低的结合能侧移动，在16Å时，SECO向较低的结合能侧移动到大约0.4 eV的值，几乎抵消了初始真空能级的偏移。这种现象可以归因于参考文献中随着L-半胱氨酸覆盖率的增加而使银-硫键减弱。还进行了光电子产率光谱（PYS）作为附加的光谱工作，显示出银的功函数一旦降低，然后在低覆盖率下恢复。这种行为也可以归因于通过增加L-半胱氨酸的覆盖范围来削弱L-半胱氨酸与银的相互作用。SECO开始向较低的结合能侧移动，在16Å时，SECO向较低的结合能侧移动到大约0.4 eV的值，几乎抵消了初始真空能级的偏移。这种现象可以归因于参考文献中随着L-半胱氨酸覆盖率的增加而使银-硫键减弱。还进行了光电子产率光谱（PYS）作为附加的光谱工作，显示出银的功函数一旦降低，然后在低覆盖率下恢复。这种行为也可以归因于通过增加L-半胱氨酸的覆盖范围来削弱L-半胱氨酸与银的相互作用。这种现象可以归因于参考文献中随着L-半胱氨酸覆盖率的增加而使银-硫键减弱。还进行了光电子产率光谱（PYS）作为附加的光谱工作，显示出银的功函数一旦降低，然后在低覆盖率下恢复。这种行为也可以归因于通过增加L-半胱氨酸的覆盖范围来削弱L-半胱氨酸与银的相互作用。这种现象可以归因于参考文献中随着L-半胱氨酸覆盖率的增加而使银-硫键减弱。还进行了光电子产率光谱（PYS）作为附加的光谱工作，显示出银的功函数一旦降低，然后在低覆盖率下恢复。这种行为也可以归因于通过增加L-半胱氨酸的覆盖范围来削弱L-半胱氨酸与银的相互作用。