Dynamics of molecules and ions in the gas phase

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The proposal involves projects that study the way ions move in the gas phase, and how the dynamics of this motion can be used to gain information about the structure of an ion, or to manipulate it in space. One major theme examines ions formed from protein complexes.  Experiments have shown that these complexes, in the gas phase, break up into pieces that have unusual charge distributions.  Specifically, the charges do not spread symmetrically among the pieces, as one would expect. The interesting question is, "Why does this happen?". The prevailing mechanism suggests that some proteins in the complex begin to unfold during the break up, and this causes the charge distributions to become asymmetric.  Our goal is to simulate these processes using computers running molecular dynamics codes, in an attempt to understand this mechanism in detail, and to control it.  One important part of this mechanism is the transfer of protons between different parts of the ion.  In the gas phase, the way protons move can be very different than in solution.  However, understanding proton transfer is very important for mass spectrometrists, who currently are using these gas phase species to sequence amino acids, and thus identify the proteins that exist in a cell or other biological sample. A second major theme is concerned with separating ions with different shapes.  The idea is to develop methods that will preferentially separate ions with non-spherical shapes from those that are spherical.  Such a technique would be very powerful for aerosol and atmospheric scientists, who analyze and study the reactions of chemicals in the environment.  Along the same lines, we would like to develop a method to align ions in the gas phase, to aid experiments that probe the reactivity and behaviour of gas phase species.