LAUE TIME-RESOLVED DIFFRACTION OF MOLECULAR EXCITED STATES

分子激发态的劳尔时间分辨衍射

• 批准号: 8172000
• 负责人: PHILIP COPPENS
• 金额: $ 1.82万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2011-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8172000
• 关键词: Adsorption; Cells; Characteristics; Collaborations; Computer Retrieval of Information on Scientific Projects Database; Data; Devices; Dyes; Funding; Grant; Institution; Knowledge; Light; Measurement; Methods; Molecular; Optics; Phase; Physiologic pulse; Process; Pump; Research; Research Personnel; Resolution; Resources; Semiconductors; Source; Spottings; Surface; Testing; Time; United States National Institutes of Health; Work; X ray diffraction analysis; X-Ray Diffraction; anatase titanium dioxide; chromophore; design; research study; titanium dioxide

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Beamtime is requested for photocrystallographic time-resolved experiments using single- and multi-pulse Laue diffraction. As part of the project experimental and data-reduction methods are being revised to maximize the accuracy of the Laue intensities and the optical resolution. We are using the 'seed-skewness' method of spot integration (Bolotovsky & Coppens, J. Appl. Cryst. 30 244-253, 1997)which is profile-independent and well suited for the profile changes observed at different time point in the 100ps-1 ms delay range in time-resolved Laue experiment. We are analyzing instabilities in the single-pulse intensities in collaboration with Tim Graber, who has identified several sources of the fluctuations in very recent test experiments. Knowledge of the geometry changes of molecules on excitation and their relation to lifetimes and adsorption of chromophores on substrates is of crucial importance for the design of molecular devices used in light capture. In photovoltaic cells sensitizer-dye molecules are adsorbed on a semiconductor surface, which is typically composed of the anatase phase of titanium dioxide. The proposed work involves crystalline phases of titanium dioxide nanoclusters which reproduce the surface characteristics of the anatase phase. The periodic arrangement of the nanoclusters in these materials allows detailed X-ray diffraction determination of the geometry of the adsorbed molecules in their ground state, and, by use of ultrafast time-resolved pump-probe diffraction methods at picoseconds-resolution, determination of the geometry changes of both the adsorbent and the substrate on excitation by light. The structural results are to be correlated with spectroscopic measurements and theoretical calculations to obtain atomic-resolution understanding of the processes that take place on molecule-coated semiconductor surfaces as a result of light exposure.

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