A Frequency Domain Fluorescence Lifetime Instrument for the Aladdin Synchrotron Light Source

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This proposal describes the construction of a research resource at the Aladdin Synchrotron, University of Wisconsin- Madison, dedicated to time-resolved fluorescence spectroscopy of biological systems. The specific aims are to (1) build a frequency domain fluorometer that exploits the time structure of the Aladdin Synchrotron light source especially its picosecond resolution and broad excitation wavelength capabilities; (2) establish a preparative biological sample laboratory in conjunction with the fluorescence facility; (3) train students in the principles of frequency domain methods using synchrotron radiation, and to operate the facility; and (4) conduct core research on the dynamics of biological systems. To accomplish these goals, we will draw upon our prior experiences (1) establishment of a synchrotron radiation facility at Frascati (Italy), (2) development of frequency domain fluorescence instrumentation exploiting the harmonic content of pulsed sources, (3) design and construction of a microwave superheterodyning fluorometer and (4) establishment and operation of an international luminescence center (Laboratory for Fluorescence Dynamics), which provides biological scientists with a state-of-the-art fluorescence laboratory coupled with a functional biochemistry laboratory. Fluorescence time-resolved experiments are invaluable in exploring the dynamics of biological systems such as protein and nucleic acid biopolymers, or cellular organelles.. The uniqueness of the Aladdin Synchrotron source in terms of time resolution, brightness, continuous excitation wavelengths (ultraviolet and visible), phase stability, and pulse-to-pulse amplitude stability, makes it the best choice in the United State for a synchrotron radiation laboratory. After the initial construction period, the Fluorescence Synchrotron Radiation Laboratory will become a research resource for the life sciences community. Preliminary experiments at Aladdin have fully demonstrated the feas ibility of frequency domain measurements in the multibunch mode and have confirmed our predictions in terms of signal stability and signal intensity which are crucial characteristics for the study of complex biological systems.