Two-photon two-color excited polarized fluorescence in biologically relevant molecules: investigation of molecular excited state structure and dynamics

在一个联合研究项目的框架内，将研究生物相关分子的排列、取向和旋转关联时间。分子将在不同的偏振方案(这里是400 nm和800 nm左右的可调辐射)下使用两个彩色双光子(2c2p)激光脉冲来对准和定向。还观察到了不同偏振角下的荧光。使用两个不同光子的优势是双重的：可以达到更短的波长(最低可达265 nm)，使无标记蛋白质检测成为可能，并且与使用相同光子的双光子激发相比，分子的不同排列成为可能。由于扩散过程，初始排列的分子最终将按各向同性分布。我们打算确定相应的旋转关联时间，它包含了分子与其周围分子相互作用的信息。在原理证明中，对PTP进行了研究。研究工作将集中在色氨酸和吲哚的研究上，色氨酸是探测蛋白质的特征生色团，吲哚是一种显示出一些不寻常的光谱特征的分子。此外，其他小组也对吲哚进行了一些2c2p实验。Vasyutinskii的研究小组将从理论和实验上支持这一结果。

In the framework of a joint research project the alignment, orientation and rotational correlation time of biological relevant molecules will be studied. The molecules will be aligned and oriented using two color two photon (2c2p) laser pulses under different polarization schemes (here tunable radiation around 400nm and 800nm). The fluorescence is observed for different polarization angle as well. The advantage of using two different photons is twofold: shorter wavelengths (down to 265nm) can be reached making label-free proteine detection possible and different alignments of the molecules become possible compared to two photon excitation using identical photons. Due to diffusion processes, the initial aligned molecules will finally be distributed isotropically. We intend to determine the corresponding rotational correlation time which contains information on the interaction of the molecule with its surrounding. In a proof of principle PTP was investigated. The research work will be focused on the study of tryptophan, as characteristic chromophore for probing proteins, and indole, a molecule which shows some unusual spectroscopic features. In addition, some 2c2p experiments on indole have been performed by other groups. The results will be theoretically and experimentally supported by the research group of O. Vasyutinskii.