A carbon quantum dot (CQD) sample series was synthesized from citric acid and varying concentrations of thiourea. The highest (sample 1) and lowest (sample 2) concentrations of thiourea exhibited unique visual effects and electronic structures. X-ray excited optical luminescence (XEOL) along with UV-visible spectroscopy provided unique insight into the absorption and emission mechanisms of samples 1 and 2, where only sample 2 emitted XEOL. Sample 1 exhibited the commonly observed aggregation caused quenching (ACQ) effects in the solid state. While sample 2 displayed unique aggregation induced emissions (AIE) effects upon exciting the sample above the C K edge. The AIE and ACQ sample differences were suspected to be from S moiety differences arising from the varying thiourea concentrations during synthesis. Furthermore, x-ray absorption spectroscopy (XAS) in modes of total electron yields (TEY) and partial fluorescence yields (PFY) allowed the identification of specific core and surface states of the CQDs. It was discovered that thiophene moieties were uniquely formed in the AIE sample’s surface and not anywhere in the ACQ CQD sample. The thiophene surface functionality is believed to be a significant contributor to the AIE effects seen in the XEOL studies. Understanding and preventing the common CQD ACQ mechanism allows the application of CQDs in solid lighting applications.

从柠檬酸和不同浓度的硫脲合成了碳量子点（CQD）样品系列。最高（样品1）和最低（样品2）浓度的硫脲表现出独特的视觉效果和电子结构。X射线激发光致发光（XEOL）与紫外可见光谱一起提供了对样品1和2吸收和发射机理的独特见解，其中样品2仅发射XEOL。样品1在固态下表现出通常观察到的聚集引起的猝灭（ACQ）效应。样品2在激发到高于C K时显示出独特的聚集诱导发射（AIE）效应边缘。怀疑AIE和ACQ样品差异是由于合成过程中硫脲浓度变化引起的S部分差异所致。此外，以总电子产率（TEY）和部分荧光产率（PFY）的模式进行的X射线吸收光谱（XAS）可以识别CQD的特定核心和表面状态。发现噻吩部分独特地形成在AIE样品的表面中，而不是在ACQ CQD样品中的任何地方。据信噻吩表面功能是XEOL研究中看到的AIE效应的重要贡献。了解并防止常见的CQD ACQ机制可将CQD应用在固体照明应用中。