UC Irvine

Two-dimensional infrared spectroscopy (2D IR) is a rapidly growing field. Many of the problems studied with this technique, and especially those involving biomolecules, require the detection of very weak signals. To further advance the technique forward, the signal-to-noise ratio needs to be improved. This dissertation details a method for noise reduction, called “smart referencing,” and details several considerations required for increasing the signal when using a pulse shaper. Using these improvements, the ultrafast vibrational dynamics and local environment sensitivity of the tyrosine ring mode in the enkephalin/bicelle system were studied using 2D IR. The 2D IR spectra revealed a new and unusual line-shape distortion for this ring mode. We modeled this distortion with a 3rd order response function formalism and a phenomenological set of master equations to better understand its origin. The 2D IR results also show that the tyrosine ring mode is sensitive to its local environment.