Mapping vibrational frequencies
Two-dimensional IR spectroscopy can measure molecular dynamics at the femtosecond (quadrillionth of a second) timescale, which is the vibrational frequency of a chemical bond. The method is used to correlate different vibrational frequencies of a molecule, in order to learn about its structure as well as its chemical environment. Combined with microscopy, the method offers a spatial resolution of 20 microns, about the size of a human skin cell.
"Consider a system of coupled springs: you can pluck one spring and see the energy transfer from this one oscillator to all the other springs in the system," Baiz explained. "It's the same effect with molecules. The laser excites one vibration which then relaxes into other nearby vibrations on the same molecule or its neighbors, and where the vibrational energy ends up tells us about the structure and environment of the molecule."
Multiple factors contributed to the success of Tokmakoff's team, which conducted preliminary experiments for two years at MIT, that enabled the group to plot the best way to develop the new method. Once Tokmakoff joined the UChicago faculty in 2013, his startup funds financed the purchase of the sophisticated and expensive equipment that his team needed to implement the plan.
"The facilities are excellent here" said Baiz, referring to Tokmakoff's laboratory space in the Gordon Center for Integrative Science, which is equipped with stringent temperature and humidity controls, the most technologically advanced optical components, and a brand new microscope.
Also important was the purchase of a new pulse shaper that enabled the researchers to modulate individual laser pulses in a way that traditional optics cannot do, and developing a new way of collecting data that involved a different geometric alignme
|Contact: Steve Koppes|
University of Chicago