Ex situ characterization techniques in molecular beam epitaxy (MBE) have inherent limitations, such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber. In recent years, the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques. These techniques, such as reflection high-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, allow direct observation of film growth processes in real time without exposing the sample to air, hence offering insights into the growth mechanisms of epitaxial films with controlled properties. By combining multiple in situ characterization techniques with MBE, researchers can better understand film growth processes, realizing novel materials with customized properties and extensive applications. This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research. In addition, through further analysis of these techniques regarding their challenges and potential solutions, particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information, we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

随着全球化石资源的不断消耗，可再生资源的转化利用已成为科研工作者的关注焦点。由生物质经过生物或化学方法转化而获得的生物基低碳醇的催化转化是近些年来研究的热点。为高效率探索多种模型催化反应，该文研制了气态流动鼓泡发生器来替代传统的固定床反应器的进料过程，目的是进行不同的模型催化反应探索实验。通过对比二者的实验结果显示，该设备具有误差小、试验快、操作简单等特点，且其设计所占空间小、便携等优点，适用于多种原位表征技术。通过将气态流动鼓泡发生器与原位漫反射红外光谱联用，使学生深入学习了红外理论知识和仪器设备的工作原理，将学生们学到的催化学科的相关基础知识进行融会贯通。气态流动鼓泡发生器不仅辅助科研实验的探索，还可拓展到实验教学的应用，提升学生的科研创新能力，为科教融合、教研一体提供了新范式。

二维编织碳化硅纤维增强碳化硅复合材料(2D-SiC_f/SiC)在航空领域中得到广泛使用, 然而该材料层间强度低, 使其易萌生层间裂纹, 引起分层破坏。为此, 本工作采用楔形双悬臂梁法(W-DCB)和悬臂梁法(DCB)开展了层间I型断裂试验, 获得了2D-SiC_f/SiC的层间裂纹驱动的加载数据, 得到了其裂纹端口张开力及张开位移变形曲线。在试验加载过程, 通过光学显微镜监测了视觉裂纹扩展过程, 探究了2D-SiC_f/SiC的层间I型裂纹扩展规律。结合理论分析和裂纹视觉特征解释了加载曲线拐点及其他特征点的断裂力学含义。利用扫描电子显微镜分析了2D-SiC_f/SiC的层间断面特征, 揭示了断面分层裂纹扩展机制。结果表明: W-DCB方法测量的2D-SiC_f/SiC层间I型初始能量释放率与DCB方法等效; 2D-SiC_f/SiC层间I型断裂过程中, 裂纹端口变形曲线的多峰性不符合经典线弹性断裂力学预测的加载峰后特征, 反映了2D-SiC_f/SiC层间约束关系的复杂性; 层间断面为结构性非完全损伤, 发生了局部纤维桥连现象。

Manganese (Mn) doped cadmium sulphide (CdS) nanoparticles were synthesized using a chemical method. It was possible to decrease CdS : Mn particle size by increasing Mn concentration. Investigation techniques such as ultraviolet?visible (UV?Vis) absorption spectroscopy and photoluminescence (PL) spectroscopy were used to determine optical properties of CdS : Mn nanoparticles. Size quantization effect was observed in UV?Vis absorption spectra. Quantum efficiency for luminescence or the internal magnetic field strength was increased by doping CdS nanoparticles with Mn element. Orange emission was observed at wavelength ~630 nm due to ⁴T₁ → ⁶A₁ transition. Isolated Mn²⁺ ions arranged in tetrahedral coordination are mainly responsible for luminescence. Luminescence quenching and the effect of Mn doping on hyperfine interactions in the case of CdS nanoparticles were also discussed. The corresponding weight percentage of Mn element actually incorporated in doping process was determined by atomic absorption spectroscopy (AAS). Crystallinity was checked and the average size of nanoparticles was estimated using the X-ray diffraction (XRD) technique. CdS : Mn nanoparticles show ferromagnetism at room temperature. Transmission electron microscopy (TEM) images show spherical clusters of various sizes and selected area electron diffraction (SAED) patterns show the polycrystalline nature of the clusters. The electronic states of diluted magnetic semiconductors (DMS) of Ⅱ?Ⅵ group CdS nanoparticles give them great potential for applications due to quantum confinement. In this study, experimental results and discussions on these aspects have been given.

超短激光脉冲作为产生阿秒激光与探索物质微观世界的重要工具，其时间特性的精确测量尤为重要。介绍了几种少周期激光脉冲的产生以及常用的表征技术，并将表征技术在广义上分为频域测量与时域测量两大类。在频域测量中，通过测量非线性过程产生的光谱信息来反演重构超短激光脉冲的包络及相位；在时域测量中，利用“超快门开关”直接对脉冲的光场信息进行采样，从而获取时间特性。两类技术在应用场景上各有侧重，频域测量因其装置简便快捷而被广泛应用在快速表征的实验场景中，而时域采样则因为可以直接获得光电场信息，常用于与光电场直接相关的超快物理实验。

盖髓剂对于保存牙髓和治疗龋病具有重要作用。临床常用的三种盖髓剂的治疗效果存在较大差异, 如何依据病情选择恰当的盖髓剂亟需相关对比研究予以指导。本研究旨在对临床常用的三种盖髓剂: 齿科氧化锌丁香酚水门汀(ZnO)、自固化氢氧化钙(Dycal)和光固化氢氧化钙间接盖髓剂(Calcimol)的形貌、成分以及理化性能进行表征, 并通过体外细菌和细胞培养实验对其抗菌性和生物相容性进行对比评价。实验结果表明, 齿科氧化锌丁香酚的疏水性能较强, 其有效成分ZnO可持续释放Zn离子, 呈现出优异的抗菌性能; Dycal和Calcimol具有相似的结构形貌和成分, 但Dycal相对疏水, 能持续释放Ca离子, 在周围形成碱性微环境, 从而赋予其抗菌性和较好的生物相容性; Calcimol为亲水材料, 便于临床操作, 钙离子释放量少, 抗菌性稍弱, 但生物相容性优异。本研究结果为临床上以龋病程度及牙髓健康状况为依据，选择合适的盖髓剂提供了实验基础。