Dynamic Light Scattering Microscope

Jonathan Celli, Brian Gregor (Physics)

A Dynamic Light Scattering Microscope has been built on the platform of an upright microscope. The instrument is a simplified and more robust form of a design using a phase telescope [1]. Calibration data from the diffusion of polystyrene spheres in water are in agreement with expected results and data has also been acquired from two complex biological molecules, Porcine Gastric Mucin and Matrigel. For both samples, data has been acquired by scattering from the gels as well as scattering from tracer particles (polystyrene spheres). In the latter case, information about the viscoelastic properties of the biological gels is obtained from studying the dynamics of the tracer particles. [1] P.D. Kaplan and D. A. Weitz, Light-Scattering Microscopy," Applied Optics, 38 4151-4157 (1999).

More information on the DLS Microscope

Ultra Fast 2D Infrared Spectroscopy

Collaboration (Prof L. Ziegler, Chemistry; Prof Ken Rothschild, Physics)
Graduate Students: Logan Chieffo, Jason Amsden

A collaboration project involves the development of an ultra fast two-dimensional infrared spectrometer in order to study interactions of light on fundamental biological molecules and systems. Traditional (1D) infrared spectroscopy can, at best, obtain spectra on a nanosecond time scale, and the spectra contain ambiguously broad lineshapes, which cannot be interpreted. Utilizing multiple ultra fast pulses, varied both in time and frequency, spectra can be obtained on a timescale of several hundred femtoseconds. These multidimensional spectra provide a direct measurement of the mechanism that leads to line width broadening, as well as information on the vibrational couplings in the molecule. The data obtained can be used to determine between homogenous and inhomogeneous broadening and to monitor the structure of a molecule on a femtosecond timescale.
A spectra physics Hurricane titanium sapphire laser is used to generate thirty femtosecond pulses, which are tuned to the appropriate wavelength for experimental conditions using non-linear crystals and optical parametric amplifiers.

Standing Wave Total Internal Reflection Raman Microscope

Information on this project will be coming soon