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Rob's work focuses on the detection and characterization of complex organic chemistry in astrobiological environments, especially Titan a moon of Saturn. A hallmark of organized pre-biotic chemistry is the appearance and an enantiomeric excess. We are developing small, lightweight sensors suitable for space flight applications that are capable of determining this excess. Two major approaches are used.
In the first approach, mass-sensitive piezoelectric sensors such as surface acoustic wave devices and quartz-crystal microbalances are coated with thin-films of a chiral selector. Differential absorption of enantiomers into the chiral films enables detection of enantiomeric excess. In the second approach, thin layers of silica beads are modified with a chiral selector and a fluorescent dye. In these sensors, differential absorption of enantiomers leads to a change in the fluorescent properties of the beads.
The chemistry of Titan is studied through the use of simulated Titan-organic photoproducts, called tholins. These tholins are produced by passing an electrical discharge through a mixture of nitrogen and methane and collecting the resulting polymers. We have studied the fluorescence properties of these tholins, as well as using gel-permeation chromatography to characterize them by molecular weight. Ultraviolet absorption and mass spectrometry characterize the tholins. We have also developed a gas-chromatography-ultraviolet absorption system to classify the tholins according to functional group.
In other work, we study collisional activated reactions within molecular clusters in the gas phase using an electrospray ionization ion-trap mass spectrometer. We phosphorolate serine-, tyrosine-, and threonine-containing peptides and have alkilated DNA and peptides containing aspartic or glutamic acid. Modification of biomolecules in the gas phase has promise for rapid, in-situ detection and analysis of complex systems of biomolecules.
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Beauchamp Research Group |
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