Past Research

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We use our pulse shaper and an evolutionary algorithm to build pulses which optimize the populations of certain vibrational levels over others. Phase optimizations of the shaped mid-IR pulse improved the ratio of the targeted peaks by 2.2-5.8 times the transform-limited pulse.

The Amide-I mode in the peptide backbone is strongly sensitive to peptide secondary structure. We use isotope-exchange processes and solid-phase peptide synthesis to insert 13C-18O labels into peptide backbones in precisely controlled locations, shifting the Amide I frequency to a less cluttered region of the IR spectrum. This allows us to study residue-specific structure and kinetics in small peptide aggregation processes.

We built a mid-IR polarization shaper which can manipulate the polarization of our mid-IR pulses in addition to their amplitude and phase. Polarization shaping will allow us to disentangle overlapping responses in 2D IR spectra, greatly simplifying the interpretation of complex spectra.

We use 2D IR to investigate the structure and vibrational couplings of DNA. We combine our experiments with quantum calculations to account for coupling between hydrogen-bonded base pairs and between stacked bases that give rise to previously-observed vibrational circular dichroism (VCD) spectra.