10 March 2015 Laser-refrigeration of rare-earth-doped nanocrystals in water
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Proceedings Volume 9380, Laser Refrigeration of Solids VIII; 938007 (2015) https://doi.org/10.1117/12.2080356
Event: SPIE OPTO, 2015, San Francisco, California, United States
Abstract
Single-beam laser-tweezers have been demonstrated over the past several decades to confine nanometer-scale particles in three dimensions with sufficient sensitivity to measure the spring constants of individual biological macromolecules including DNA. Large laser-irradiance values (on the order of MW/cm2) commonly are used to generate laser traps which can lead to significant laser-heating within the 3D optical potential well. To date, laser-refrigeration of particles within an aqueous medium has not been reported stemming primarily from the large near-infrared (NIR) optical absorption coefficient of liquid water (0.2 cm-1 at lambda = 1020nm). In this paper we will detail the methods on how single-beam laser-traps can be used to induce and quantify the refrigeration of optically trapped nanocrystals in an aqueous medium. Analysis of the Brownian dynamics of individual nanocrystals via forward light scattering provides a way to determine both a relative and absolute measurement of particle’s temperature. Signal analysis considerations to interpreting Brownian motion data of trapped particles in nonisothermal aqueous environments, or so-called hot Brownian motion, are detailed. Applications of these methods to determining local laser-refrigeration of laser trapped nanoparticles in water show promise at realizing the first observation of particles undergoing cold Brownian motion.
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Paden B. Roder, Paden B. Roder, Bennett Smith, Bennett Smith, Xuezhe Zhou, Xuezhe Zhou, Matthew J. Crane, Matthew J. Crane, Peter J. Pauzauskie, Peter J. Pauzauskie, "Laser-refrigeration of rare-earth-doped nanocrystals in water", Proc. SPIE 9380, Laser Refrigeration of Solids VIII, 938007 (10 March 2015); doi: 10.1117/12.2080356; https://doi.org/10.1117/12.2080356
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