Fayer Lab Research Overview
The Fayer group is pursuing research on the ultrafast dynamics, interactions, and structure of a range of complex molecular systems. A major theme of the systems under investigation is that they frequently possess mesoscopic structure, that is, structure beyond that of the short range order of a molecule and its solvent shell that commonly occurs in a liquid. The types of systems under study include water in nanoconfined systems and water interacting with interfaces, ions and other species; Room Temperature Ionic Liquids (RTILs) and their effect on solutes and how they are affected by solutes; Metal Organic Frameworks (MOFs) and their properties when they are functionalized and contain solvents in their nanopores; liquid crystals and the behavior of nanodomains in the isotropic phase and the phase transition to ordered phases; polyelectrolyte fuel cell membranes and how water behaves in the membrane’s nanochannels and the nature of proton transfer in the channels; organized surfactant systems such as reverse micelles and vesicles; supercooled liquids and their dynamics as they approach the glass transition; nanoporous silica particles that are functionalized and contain solvents in the pores; and functionalized alkyl chains on silica and gold surfaces and interactions of solvents with functionalized surfaces.
In all of these systems there is complex interplay among fast molecular dynamics, intermolecular interactions, and structure. It is this interplay that gives a system its properties and determines how it functions in chemical and materials applications. Molecules are constantly moving. The time scales and influences on molecular dynamics are the key to understanding complex molecular systems. The Fayer group employs a variety of ultrafast nonlinear laser methods to directly study molecular dynamics. The methods, many of which were pioneered and developed by the Fayer group, enable us to study the dynamics of complex systems on the ultrafast time scales on which they occur, i.e., picoseconds (10-12 s) and femtoseconds (10-15 s). We employ ultrafast infrared methods, for example, two dimensional infrared (2D IR) spectroscopy, which is akin to 2D NMR but operates on time scales eight to ten orders of magnitude faster than NMR. In addition, we use polarization selective IR pump-probe and IR transient grating methods. We also use ultrafast visible non-linear methods. These include optical heterodyne detected optical Kerr effect (OHD-OKE) experiments and fast time resolved polarized fluorescence measurements. Each method is tailored to obtain specific detailed information about molecular dynamics and their relations to intermolecular interactions and structure. To compliment the experiments, we employ statistical mechanics theory of both the non-linear optical methods and material properties, and through collaborations, we use molecular dynamics simulations of the materials and experimental observables.
Brief descriptions and examples of the research that is ongoing in the Fayer labs are presented in the various sections. The following is a list of recent review and feature articles that summarize some of our work.
353. “Ultrafast 2D IR Vibrational Echo Spectroscopy,” Junrong Zheng,
Kyungwon Kwak, and M. D. Fayer Acc. of Chem. Res. 40, 75-83 (2007).
357. “Probing Dynamics of Complex Molecular Systems with Ultrafast 2D IR Vibrational Echo Spectroscopy,” Ilya J. Finkelstein, Junrong Zheng, Haruto Ishikawa, Seongheun Kim, Kyungwon Kwak, and M. D. Fayer Phys. Chem. Chem. Phys., 9, 1533-1549, (2007).
361. “Ultrafast 2D-IR Vibrational Echo Spectroscopy: A Probe of Molecular Dynamics,” Sungnam Park, Kyungwon Kwak, and M. D. Fayer Laser Phys. Lett. 4, 704-718 (2007).
369. “Water Dynamics and Proton Transfer in Nafion Fuel Cell Membranes,” David E. Moilanen, D.B. Spry, and M. D. Fayer Langmuir 24, 3690-3698 (2007).
370. “Water Dynamics – The Effects of Ions and Nanoconfinement,” Sungnam Park, David E. Moilanen, and M. D. Fayer J. Phys. Chem. B 112, 5279-5290 (2008).
379. “Dynamics of Liquids, Molecules, and Proteins Measured with Ultrafast 2D IR Vibrational Echo Chemical Exchange Spectroscopy,” M. D. Fayer Ann. Rev. P. Chem. 60, 21-38 (2008).
384. “Water Dynamics in Salt Solutions Studied with Ultrafast 2D IR Vibrational Echo Spectroscopy,” M. D. Fayer, David E. Moilanen, Daryl Wong, Daniel E. Rosenfeld, Emily E. Fenn, and Sungnam Park Acc. of Chem. Res. 42, 1210-1219 (2009).
390. “Analysis of Water in Confined Geometries and at Interfaces,” M. D. Fayer and Nancy E. Levinger Ann. Rev. Analytical Chem. 3, 89-107 (2010).
403. “Dynamics of Water Interacting with Interfaces, Molecules, and Ions,” M. D. Fayer Acc. of Chem. Res. 45, 3-14 (2012).
411. “Water in a Crowd,” M. D. Fayer, Physiology 26, 381-392 (2011).
413. “Protein Dynamics Studied with Ultrafast Two-Dimensional Infrared Vibrational Echo Spectroscopy,” Megan C. Thielges and M. D. Fayer Acc. Chem. Research 45, 1866-1874 (2012).
435. “Dynamics and structure of room temperature ionic liquids,” M. D. Fayer Chem. Phys. Lett. 616-617, 259-274 (2014).