Optical instruments for characterization in the nano-scale

Optics;Fluorescence correlation spectroscopy (FCS);Quantum dots;Diffraction gratings;Long Trace Profiler

Sheung, Janet Yue Hung

关键词: Optics;    Fluorescence correlation spectroscopy (FCS);    Quantum dots;    Diffraction gratings;    Long Trace Profiler;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/97247/SHEUNG-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Optical (light-based) instruments are often some of the most precise in many fields, owing to the wide availability of stable and low bandwidth lasers such as those of HeNe and single mode solid state types. Rulers of nanoscale precision and accuracy can be built with such lasers as light sources. This thesis two such instruments, the Florescence Correlation Spectroscope for determination of hydrodynamic size of quantum dot bioprobes to nanometer precision in part one, and the Long Trace Profiler/Optical Slope Measurement System for characterization of line spacing errors in X-ray blazed synchrotron diffraction gratings to the Angstrom scale in part two.Quantum dots have long been a reliable label in single-molecule applications due to their brightness and photo-stability. These desirable traits come at a price of a large hydrodynamic size, often exceeding that of the protein to be labeled and thus perturbing the biological system under study from its natural state. In size-sensitive applications researchers have used quantum dot probes with less robust encapsulations, and this loss of robustness present challenges for size characterization using traditional chromatography techniques. We discuss the use of fluorescence correlation spectroscopy (FCS) in these situations and report the hydrodynamic diameters, measured by FCS, of quantum dots we have previously successfully employed in the study of a spatially-confined cellular process where both smallness of reporter and brightness to achieve nanometer-scale resolution were necessary. We report that for four colors spanning the visible spectrum our quantum dot probes, both carboxylate and functionalized with streptavidin, are smaller than commercially available counterparts. In particular, our altered amphiphilic ligand coating resulted in a decrease in hydrodynamic diameter of 2.3nm - 4.8nm.The Optical Slope Measurement System Argonne National Laboratory's Advanced Photon Source (APS-OSMS) is capable of resolving slope errors in X-ray mirrors down to 50 nanoradian. Now the Department of Energy Synchrotron facilities (Advanced Light Source at Lawrence Berkeley National Lab, National Synchrotron Light Source II at Brookhaven National Lab, along with Argonne APS) need the capability to characterize X-ray diffraction gratings developed in-house, with the APS-OSMS best positioned to receive the necessary additional optics. The development of the hardware additions are discussed, along with successful test scans. Metrology work for three of Brookhaven Lab's newest diffraction gratings are already planned on this newly expanded instrument.