敏感样品激光热效应抑制方法

The Suppression Method of Raman Laser Thermal Effect for Sensitive Samples

激光共聚焦显微拉曼光谱被广泛用于研究分子结构、成键效果、载荷及内部应力。拉曼光谱的信号强度和信号质量对分析而言尤为重要。然而拉曼激光照射在敏感样品表面会产生热效应进而造成结构破坏。样品受损的部位会出现坍塌和发亮的现象。为了获取高质量的拉曼光谱,实现无损表征,提出了添加KBr作为散热剂消除激光热效应的方法。选择了一系列在激光辐射下易受损的碳材料作为研究对象,并探索了样品的碳含量、KBr的添加量与拉曼光谱参数、信号强度之间的关系。实验结果表明KBr的添加可有效抑制敏感样品被拉曼激光破坏。当KBr和材料的质量比为1∶2时,可实现该材料的准确无损拉曼光谱检测。此外,不同微区检测出来碳材料的石墨化度R值非常接近;随着碳含量的增加,D峰位置向低波区域位移~3cm^(-1),G峰位置向高波区域位移~2cm^(-1),D峰和G峰的峰位差值增加,强度比减小,样品的有序性增加。

Laser-micro confocal Raman spectroscopy is widely used to study molecular structure,bonding effects,loading,and internal stress.The signal intensity and quality of Raman spectra are particularly important for the analysis.However,Raman laser irradiation on the surface of sensitive samples produces thermal effects and,thus,structural damage.The damaged parts of the sample collapse and shine.To obtain high-quality Raman spectra and realize non-destructive characterization,this paper innovatively proposes adding KBr as a heat sink to eliminate the thermal effect of laser.A series of carbon materials that are easily damaged under laser radiation were selected as the research objects,and the relationships between the carbon content of the samples,the addition of KBr,and the Raman spectral parameters and signal intensity were explored.The experimental results show that adding KBr can effectively inhibit the sensitive samples from being damaged by the Raman laser.When the addition ratio of KBr is 1∶2,accurate and nondestructive Raman spectroscopic detection of this material can be realized.In addition,the graphitization R values of carbon materials detected in different microregions are very close to each other;with the increase of carbon content,the position of the D peak is shifted to the low-wave region by~3cm^(-1),and the position of the G peak is shifted to the high-wave region by~2cm^(-1),and the difference between the peak positions of the D peak and the G peak is increased,with a decrease in the intensity ratio,and an increase in the ordering of the samples.