Femtosecond laser system

在过去的三十年中，基于相干反斯托克斯拉曼散射或受激拉曼散射的非线性拉曼显微镜技术已经成为研究生物和材料科学样品的有吸引力的工具。与荧光技术相比，这两种方法的主要缺点是灵敏度不足。本文的主要目的是建立一种灵敏度可与共聚焦荧光显微镜相媲美的相干反斯托克斯拉曼散射显微镜和受激拉曼散射显微镜，并将其应用于各种不同的实验。为此，应利用非线性拉曼信号的电子预共振增强。这需要使用具有合适电子吸收的发色团。虽然我们和另一个小组最近已经证明了计划实验的原理，但迄今为止进行的实验使用的是在近红外光谱区域工作的激发激光器。这限制了所提出的方法在非常小的分子范围内的适用性。因此，我们主要目的的一个重要部分是将激发波长进一步转移到可见光谱区域。这将使我们有机会接触到大量特征良好的发色团。实验装置建成后，主要用于研究生物样品和材料样品的各类样品。除此之外，我们还希望利用该装置进一步提高检测单个分子振动光谱的灵敏度极限。

Over the last three decades, non-linear Raman microscopy techniques based on coherent anti-Stokes Raman scattering or stimulated Raman scattering have become attractive tools for the investigation of biological and material scientific samples. Compared to fluorescence techniques, the main drawback of both methods is their lack in sensitivity. Main aim of this proposal is the implementation of a setup for coherent anti-Stokes Raman scattering microscopy and stimulated Raman scattering microscopy with sensitivities comparable to that of confocal fluorescence microscopy and its application in various different experiments. To this end, electronic pre-resonance enhancement of the non-linear Raman signals shall be exploited. This requires the use of chromophores with suitable electronic absorptions. While the principle of the planned experiment has recently been demonstrated by us and another group, experiments performed so far used excitation lasers working in the near-infrared spectral region. This limits the applicability of the proposed approach to very small range of molecules. An important part of our main aim therefore is to shift the excitation wavelength further into the visible spectral region. This would give access to a huge range of well characterized chromophores. Once built, the experimental setup shall mainly be employed to investigate various types of samples from biology and material sample. Apart from this, we also want to use the setup to further push the sensitivity limits to detecting vibrational spectra of single molecules.