Presentation Type
Poster
A Custom Built Apparatus for Measuring the Rotational Dynamics of Nanoparticles Using Depolarized Dynamic Light Scattering
Abstract
Rotational diffusion measurements with Depolarized Dynamic Light Scattering (DDLS) provide detailed information on nanoparticle size and shape anisotropy. There are several obstacles to their application in practice, though. Among them is that depolarized light scattering signals are typically quite weak, requiring measurement durations of hours or days to collect one correlation function. We have designed a custom built DDLS apparatus with improved capabilities for measuring translational and rotational motion of molecules. The traditional method of counting scattered photons into fixed time bins is inefficient when dealing with the low scattering intensities common for depolarized light scattering signals. Instead, we have adapted the time-tagged time-resolved algorithm, which counts the relative spacing between photon arrivals. The setup utilizes a National Instruments USB-6210 counter/timer board with a 20MHz timebase to label photon arrival times and a recently developed software algorithm to calculate the autocorrelation function. The optical set-up uses a glan-thompson polarizer-analyzer configuration for selection of the polarization of scattered light. We have characterized the measurement capabilities of the instrument by determining the translational and rotational dynamics of a system of anisotropic Au nanorods.
Categories
Engineering/Physical Science
Research Type
Thesis
Mentor Information
Dr. Martin Muschol
A Custom Built Apparatus for Measuring the Rotational Dynamics of Nanoparticles Using Depolarized Dynamic Light Scattering
Rotational diffusion measurements with Depolarized Dynamic Light Scattering (DDLS) provide detailed information on nanoparticle size and shape anisotropy. There are several obstacles to their application in practice, though. Among them is that depolarized light scattering signals are typically quite weak, requiring measurement durations of hours or days to collect one correlation function. We have designed a custom built DDLS apparatus with improved capabilities for measuring translational and rotational motion of molecules. The traditional method of counting scattered photons into fixed time bins is inefficient when dealing with the low scattering intensities common for depolarized light scattering signals. Instead, we have adapted the time-tagged time-resolved algorithm, which counts the relative spacing between photon arrivals. The setup utilizes a National Instruments USB-6210 counter/timer board with a 20MHz timebase to label photon arrival times and a recently developed software algorithm to calculate the autocorrelation function. The optical set-up uses a glan-thompson polarizer-analyzer configuration for selection of the polarization of scattered light. We have characterized the measurement capabilities of the instrument by determining the translational and rotational dynamics of a system of anisotropic Au nanorods.
