Department Chemie, Universität Konstanz, D-78457 Konstanz, Germany.
Phys Chem Chem Phys. 2020 Sep 30;22(37):21421-21427. doi: 10.1039/d0cp03221b.
Pre-electronic resonance enhancement can increase the sensitivity of non-linear Raman microscopy to the single molecule detection limit. A major problem, however, is the generation of background signal due to unwanted linear and non-linear photophysical processes. In this work, we report the setup of a novel detection scheme for stimulated Raman scattering microspectroscopy based on the simultaneous modulation of pump and Stokes beam. Apart from allowing the parallel detection of stimulated Raman loss and gain (SRL and SRG), the setup gives access to the quantitative analysis of different sources of background signal. We report spectrally and temporally resolved measurements on three exemplary rhodamine dyes and derive the contributions of two-photon absorption and stimulated emission to their SRL, SRG, and stimulated Raman excited fluorescence signals. These results give guidelines for the further improvement of the sensitivity of non-linear Raman micospectroscopy under electronic pre-resonance conditions.
预电子共振增强可以提高非线性拉曼显微镜对单分子检测极限的灵敏度。然而，一个主要问题是由于不需要的线性和非线性光物理过程而产生的背景信号。在这项工作中，我们报告了一种基于泵浦和斯托克斯光束同时调制的新型受激拉曼散射微光谱检测方案的设置。除了允许同时检测受激拉曼损耗和增益（SRL 和 SRG）之外，该设置还可以对不同背景信号源进行定量分析。我们报告了三种典型的若丹明染料的光谱和时间分辨测量，并得出了双光子吸收和受激辐射对它们的 SRL、SRG 和受激拉曼激发荧光信号的贡献。这些结果为在电子预共振条件下进一步提高非线性拉曼微光谱学的灵敏度提供了指导。
