When photons impinge on a substrate, most scatter with the same frequency (elastic scattering or Rayleigh dispersion) and only 10⁻⁷ scatter with a different energy (inelastic scattering). This inelastic interaction (Raman scattering) exchanges energy in the region of molecular vibrational transitions for crystalline and amorphous materials. Raman bands in a spectra represent vibrational transitions, like infrared, however the selection rules are different. Typically, the vibrations that are intense in Raman are weak in infrared and vice versa. A remarkable feature of the Raman effect is that it is highly sensitive to nanocrystals, even below 4 nm, which are too small to generate XRD patterns. Plasmonic enhancement, like surface‐enhanced Raman spectroscopy (SERS) boost the Raman signal by 10⁴, providing single‐molecule detection capability. Glass, quartz, and sapphire are transparent to Raman effect (depending on the energy of the incident excitation radiation), which makes it ideal to examine materials under reaction conditions (in‐situ cells and operando reactors that operate over a broad range of temperature, pressures, and environments). Raman spectroscopy emerged in the 1930s; however, infrared spectrometry displaced it. With the advent of powerful lasers in the 1970s, more researchers began to apply Raman routinely. In 2019, the Web of Science indexed 20 400 articles mentioning Raman against 50 000 articles mentioning infrared. Chemical engineers apply Raman less frequently than in material science, physical chemistry, and applied physics, with 887 articles vs 6250, 3700, and 3510 for the other disciplines. A bibliometric analysis identified four research clusters centred on thin films and optics, graphene and nanocomposites, nanoparticles and SERS, and photocatalyst.

中文翻译：

---

化学工程中的实验方法：拉曼光谱

当光子撞击基板时，大多数散射具有相同的频率（弹性散射或瑞利色散），只有10 ^-7散射具有不同的能量（非弹性散射）。这种非弹性相互作用（拉曼散射）在晶体和非晶态材料的分子振动跃迁区域交换能量。光谱中的拉曼带代表振动跃迁，例如红外，但是选择规则不同。通常，拉曼中强烈的振动在红外线中较弱，反之亦然。拉曼效应的显着特征是它对纳米晶体高度敏感，即使小于4 nm，纳米晶体也太小而无法生成XRD图案。等离子体增强，例如表面增强拉曼光谱（SERS），可使拉曼信号增强10 ⁴，提供单分子检测功能。玻璃，石英和蓝宝石对拉曼效应透明（取决于入射激发辐射的能量），这使其成为在反应条件下（原位电池和操作腔）检查材料的理想选择在很宽的温度，压力和环境范围内运行的反应堆）。拉曼光谱法于1930年代出现。然而，红外光谱法将其置换。随着1970年代强大激光的出现，越来越多的研究人员开始例行应用拉曼光谱。2019年，《 Web of Science》将20400篇提到拉曼的文章与5万篇提到红外的文章进行了索引。与材料科学，物理化学和应用物理学相比，化学工程师使用拉曼的频率更低，相对于其他学科而言，有887篇文章，而不是6250、3700和3510。文献计量分析确定了四个研究领域，重点是薄膜和光学，石墨烯和纳米复合材料，纳米颗粒和SERS以及光催化剂。