论文部分内容阅读
本文用电子能谱(XPS 和 AES)研究了不同波长光照射后,镀银层表面膜的组成和状态的变化,结果表明:(1)光波的致变色能力按以下顺序逆降,2537(?)>3650>日光,(2)同一波长光照射时间越长,变色愈甚;(3)应用俄歇参数方法进行表面元素价态分析,发现2537照射18小时表面约有3/7的银为 Ag_2O、照射24小时后表面约有3/17的银为 AgO;(4)XPS 测定表明,银层在大气中照射时,表面银先被氧化和氯化,随后氯化物可能转化为氧化银(Ag_2O),最后氧化银被光转化为黑色的超细颗粒的银粒子。镀银层浸在 Na_2S 溶液中,然后将一半面积提出液面,让其露在液面上的大气中,结果浸在Na_2S 液中的部分不变色,露在大气的部分却变为兰色。通过 Ag(3d)、S(2p)结合能以及M_4VV、M_5VV 俄歇峰的测定,证明未变色银表面仍为银,兰色层则是 Ag_2S。因此,镀银层浸入Na_2S 溶液后在大气中的变色反应可表示为4Ag+O_2+2H_2O+2Na_2S→2Ag_2S+4NaOH
The results show that: (1) The induced discoloration of light waves decreases in the order of 2537 (?), )> 3650> daylight, (2) the longer the same wavelength of light irradiation, the more discoloration; (3) the application of Auger parameter method for surface element valence analysis found that 2537 irradiated 18 hours surface of about 3/7 silver Ag_2O, about 3/17 of the silver surface is AgO after irradiation for 24 hours; (4) XPS measurement shows that when the silver layer is irradiated in the atmosphere, the surface silver is oxidized and chlorinated first, and then the chloride may be converted into silver oxide Ag_2O), and finally the silver oxide is converted into silver particles of black ultrafine particles. The silver plating layer is immersed in the Na 2 S solution, and then half of the area is raised to expose the atmosphere above the liquid surface. As a result, the portion immersed in the Na 2 S solution does not change color and the portion exposed to the atmosphere turns blue. The Ag (3d), S (2p) binding energies and the M_4VV, M_5VV Auger peak were measured to prove that the surface of the untreated silver is still silver and the blue layer is Ag_2S. Therefore, the silver discoloration reaction in the atmosphere after immersion in Na 2 S solution can be expressed as 4Ag + O 2 + 2H 2 O + 2Na 2 S → 2Ag 2 S + 4NaOH