Molecular Rotation Revealed at Long Working Distance by Stimulated Emission

• Main Authors: Po-Lin Lin, 林珀琳
• Other Authors: Fu-Jen Kao
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/59749351104326039430

碩士 === 國立陽明大學 === 生醫光電研究所 === 101 === Fluorescence lifetime revealed crucial information on molecular dynamics, such as the conformation of molecule and the changes of the immediate nano-environment of probed fluorophores. It is also widely used on describing various cellular parameters and the characteristics of tissue, such as, ion concentration, pH of the environment. However, the detection of fluorescence intensity is depending on the solid angle of the condenser due to incoherent nature of fluorescence process. The working distance of condenser is limited. In our experiment, the limited working distance is overcome through fabricating coherent signal by stimulated emission. We are reporting the use of stimulated emission in a pump-probe configuration to detect the molecular rotation at long working distance. Molecular rotation is strongly related to the fluorophore solvent’s immediate environment, often termed as viscosity. Measuring the time correlated anisotropy of fluorescence is a powerful method to reveal the dynamics of molecular rotation and thus viscosity. In this work, two synchronized lasers are used to detect the time-correlated fluorescence anisotropy. Their relative delay is adjusted electronically to facilitate the characterization of fluorescence anisotropy’s temporal evolution. In this way, the viscosities of glycerol、ethanol and water as solvents are characterized by measuring the ATTO 647N’s time resolved anisotropy through stimulated emission.