Lesoine Michael D, Bobbitt Jonathan M, Zhu Shaobin, Fang Ning, Smith Emily A
U.S. Department of Energy, Ames Laboratory, Ames, IA 50011, United States; Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA 50011, United States.
U.S. Department of Energy, Ames Laboratory, Ames, IA 50011, United States; Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA 50011, United States.
Anal Chim Acta. 2014 Oct 27;848:61-66. doi: 10.1016/j.aca.2014.07.040. Epub 2014 Aug 1.
A scanning angle (SA) Raman microscope with 532-nm excitation is reported for probing chemical content perpendicular to a sample interface. The instrument is fully automated to collect Raman spectra across a range of incident angles from 20.50 to 79.50° with an angular spread of 0.4±0.2° and an angular uncertainty of 0.09°. Instrumental controls drive a rotational stage with a fixed axis of rotation relative to a prism-based sample interface mounted on an inverted microscope stage. Three benefits of SA Raman microscopy using visible wavelengths, compared to near infrared wavelengths are: (i) better surface sensitivity; (ii) increased signal due to the frequency to the fourth power dependence of the Raman signal, and the possibility for resonant enhancement; (iii) the need to scan a reduced angular range to shorten data collection times. These benefits were demonstrated with SA Raman measurements of thin polymer films of polystyrene or a diblock copolymer of polystyrene and poly(3-hexylthiophene-2,5-diyl). Thin film spectra were collected with a signal-to-noise ratio of 30 using a 0.25 s acquisition time.
报道了一种具有532 nm激发光的扫描角（SA）拉曼显微镜，用于探测垂直于样品界面的化学成分。该仪器完全自动化，可在20.50°至79.50°的一系列入射角范围内收集拉曼光谱，角展度为0.4±0.2°，角度不确定度为0.09°。仪器控制驱动一个旋转台，该旋转台相对于安装在倒置显微镜载物台上的基于棱镜的样品界面具有固定的旋转轴。与近红外波长相比，使用可见波长的SA拉曼显微镜的三个优点是：（i）更好的表面灵敏度；（ii）由于拉曼信号对频率的四次方依赖性以及共振增强的可能性，信号增强；（iii）需要扫描的角度范围减小，以缩短数据采集时间。通过对聚苯乙烯或聚苯乙烯与聚（3-己基噻吩-2,5-二亚基）的二嵌段共聚物的聚合物薄膜进行SA拉曼测量，证明了这些优点。使用0.25 s的采集时间，以30的信噪比收集薄膜光谱。
