In this work, we apply surface-enhanced Raman spectroscopy (SERS) to study the kinetics of chromium Cr (III) detection in solution using EDTA and silver nanoparticles (AgNPs). We examine for the first time the effect of pH and nanoparticles’ capping agent on the kinetic mechanism of Cr (III) detection using SERS temporal variations. The full width at half maximum (FWHM) and Raman shift variations show that the mechanism of detection is composed of two steps: a first one consisting of chemical coordination between Cr (III) and AgNPs that leads to exalted chemical and electromagnetic enhancement and the second one is an aggregation process with an important optical enhancement. The obtained results showed that the first step in the detection at lower pH was five times faster than in a basic medium using citrate capped silver nanoparticles (Cit-AgNPs). On the other hand, using a capping agent with dicarboxylate groups such as oxalate (Oxa-AgNPs) led to an important enhancement in SERS detection signal (more than 30 times) compared with Cit-AgNPs, although the detection kinetic’s mechanism was slower.

中文翻译：

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pH和纳米颗粒封端剂对水中Cr（III）监测的影响：控制超灵敏环境检测器参数的动力学方法

在这项工作中，我们应用表面增强拉曼光谱（SERS）研究使用EDTA和银纳米颗粒（AgNPs）的溶液中铬Cr（III）检测的动力学。我们首次检查了pH和纳米颗粒封端剂对使用SERS时间变化检测Cr（III）动力学机理的影响。半峰全宽（FWHM）和拉曼位移变化表明，检测机理包括两个步骤：第一个步骤由Cr（III）与AgNPs之间的化学配位组成，导致化学和电磁增强一种是具有重要光学增强作用的聚集过程。获得的结果表明，在较低pH值下进行检测的第一步比使用柠檬酸盐封端的银纳米颗粒（Cit-AgNPs）在碱性培养基中的检测速度快五倍。另一方面，尽管检测动力学机制较慢，但与Cit-AgNPs相比，使用具有二羧酸酯基团的封端剂（如草酸盐（Oxa-AgNPs））可显着增强SERS检测信号（超过30倍）。