Femtosecond laser system

在过去的三十年里，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缺乏灵敏度。该方案的主要目的是实现一套灵敏度与共聚焦荧光显微镜相当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。这需要使用具有适当电子吸收的发色团。虽然我们和另一个小组最近已经证明了计划中的实验的原理，但到目前为止进行的实验使用的是工作在近红外光谱区域的激励激光。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，我们的主要目标的一个重要部分是将激发波长进一步移到可见光谱区域。这将使人们有机会接触到一大批具有良好特性的发色团。实验装置一旦建成，将主要用于对生物样品和材料样品的各种类型的样品进行研究。除此之外，我们还希望利用该装置进一步提高检测单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.