FEMTOSECOND CORRELATION SPECTROSCOPIC PROBES

拟议的研究计划将侧重于开发新的计算算法，用于复杂生物分子的微观模拟和使用相干光学光谱学进行探测。多脉冲技术有能力在非平衡状态下制备电子和振动自由度，并监测它们随后的演化，产生动力学事件的飞秒快照；能量转移路径、电荷转移、光异构化和结构涨落。我们将开发一个分子动力学程序，将含时量子化学程序(密度泛函和含时Hartree Fock)与半经典分子动力学多点关联函数算法相结合。多维技术应该揭示具有特定光谱特征的光合作用复合体的众多相干大小。要研究的系统：紫色细菌的LH2，FMO复合体，LHCII，CP29和氯小体。有关电子和能量转移路径、溶剂化动力学和振动弛豫的非局部信息将从荧光、泵浦探测和三脉冲技术中提取。将探索这些测量在改进光合作用天线结构方面的应用。将模拟酰胺I带和OH氢键网络的振动光谱。我们将研究一个小的环状10个残基的多肽(AnTamanide)和一个球状的76个残基的蛋白质(泛素)的结构和波动，重点研究AnTamanide和骨架中的氢键和苯丙氨酸侧链以及泛素中的谷氨酰胺侧链的动力学。将研究β-多肽中的蛋白质折叠及其非线性光谱的实时探测。将开发一种新的光谱算法来模拟激发态光动力学，并将其与蛋白质-色素相互作用联系起来。将应用于光动力疗法中的能量传递过程。

The proposed research program will focus on the development of new computational algorithms for the microscopic simulation of complex biological molecules and their probing using coherent optical spectroscopies. Multiple-pulse techniques have the capacity to prepare electronic and vibrational degrees of freedom in nonequilibrium states and monitor their subsequent evolution, yielding femtosecond snapshots of dynamical events; energy transfer pathways, charge transfer, photoisomerization, and structural fluctuations. A molecular dynamics code which interfaces time-dependent quantum chemistry packages (density functional and the time dependent Hartree Fock) with semiclassical molecular dynamics algorithms for multipoint correlation functions will be developed. Multidimensional techniques should reveal the multitude of coherence sizes of photosynthetic complexes with specific spectroscopic signatures. Systems to be studied: LH2 of purple bacteria, the FMO complex, LHCII, CP29, and the Chlorosome. Nonlocal information on electron and energy transfer pathways, solvation dynamics, and vibrational relaxation will be extracted from fluorescence, pump probe, and three-pulse techniques. The application of these measurements towards refining the structure of photosynthetic antennae will be explored. Vibrational spectra of the amide I band and of OH hydrogen-bonded networks will be simulated. The structure and fluctuations of a small cyclic 10 residue polypeptide (Antamanide) and a globular 76-residue protein (Ubiquitin will be studied, focusing on Hydrogen bonding and Phenylalanine side chain dynamics in Antamanide and backbone and Glutamine sidechain dynamics in Ubiquitin. Protein folding in beta-peptides and its real-time probing by nonlinear spectroscopies will be investigated. An new spectroscopic algorithm for simulating excited-state photodynamics and relating it to protein-pigment interactions will be developed. Applications will be made to energy transfer processes in photodynamic therapy.