Lauren P. DeFlores

Fourier phase microscopy for investigation of biological structures and dynamics

By use of the Fourier decomposition of a low-coherence optical image field into two spatial components that can be controllably shifted in phase with respect to each other, a new high-transverse-resolution quantitative-phase microscope has been developed. The technique transforms a typical optical microscope into a quantitative-phase microscope, with high accuracy and a path-length sensitivity of lambda/5500, which is stable over several hours. The results obtained on epithelial and red blood cells demonstrate the potential of this instrument for quantitative investigation of the structure and dynamics associated with biological systems without sample preparation.

Two-dimensional Fourier transform spectroscopy in the pump-probe geometry

Two-dimensional (2D) Fourier transform (FT) infrared spectroscopy is performed by using a collinear pulse-pair pump and probe geometry with conventional optics. Simultaneous collection of the third-order response and pulse-pair timing permit automated phasing and rapid acquisition of 2D absorptive spectra. To demonstrate the ability of this method to capture molecular dynamics, couplings and structure found in the conventional boxcar 2D FT spectroscopy, a series of 2D spectra of a metal carbonyl, and a beta-sheet protein are acquired.

Single-shot two-dimensional infrared spectroscopy

Multidimensional infrared spectroscopy is a robust tool for studying the structural dynamics of molecules. In particular, twodimensional infrared (2DIR) spectroscopy can reveal vibrational coupling among the internal modes of molecules, uncovering the transient structure of complex systems. While spectroscopically very powerful, current experimental techniques are time consuming to perform, requiring ~10(6) laser shots for a single 2DIR spectrum. In this work, we demonstrate a new technique that can acquire a full 2DIR correlation spectrum using a single ultrafast laser pulse. This apparatus will allow 2DIR spectroscopy to be extended to systems that were unattainable with previous technology, including, irreversible chemical reactions, rapid flow experiments, or with low repetition rate laser systems.

Solvation dynamics of N-methylacetamide in D2O, CDCI3 and DMSO-d6

We study amide I vibrational solvation dynamics of N-methylacetamide in D2O, CDC13, and DMSO-d6. Three pulse photon echo and 2D-IR measurements characterize the frequency correlation function, which reflects fluctuating electric fields acting on the Vibration.