Kenneth B. Eisenthal

MC 3107

work:+1 212-854-3175

Eisenthal Research Group
Selected Publications

Research Summary

The research activities of my group involve the application of lasers to the study of equilibrium and dynamic properties of molecules at liquid and solid interfaces.

To probe the very thin region (~10Å) that constitutes an interface, we use the interface selective techniques of second harmonic and sum frequency generation. Our picosecond and femtosecond lasers provide the high power needed for nonlinear spectroscopy, and the time resolution to study very fast molecular changes and motions. We have developed new methods to (1) measure the absolute orientation of molecules at liquid interfaces, (2) obtain the energetics of adsorption of neutral and charged molecules to the interface, (3) study chemical equilibria and pH at interfaces that we find are markedly different from their bulk values; and a polarity scale for liquid interfaces‹the motions and unexpected orientational phase transitions of long chain amphiphiles at the air/water interface‹using the new method of second harmonic fluctuation spectroscopy, and most recently vibrational spectroscopy, at interfaces, which greatly extends the power to probe chemical and physical phenomena at interfaces.

Using a pump/probe technique, with second harmonic generation as the probe method, has enabled us to observe dynamics at interfaces of excited state cis-trans isomerization, intermolecular energy transfer, solvation dynamics, and rotational molecular motions, which generally differ significantly from their bulk counterparts. We have recently shown that second harmonic spectroscopy can be used to selectively probe the surfaces of centrosymmetric microscopic particles of submicron to micron diameters. Among the surfaces of microscopic particles studied so far are polymer beads in aqueous solution, oil droplet/aqueous emulsions, semiconductor colloids, naturally occurring clay particles, and phospholipid liposomes.

The information obtained includes the absolute population of solutes adsorbed to the particle surface, the free energy of adsorption, the electrostatic potential and charge density of charged microscopic particles, and the observation in real time of the transport of organic molecules across a liposome bilayer. This new application of second harmonic and sum frequency spectroscopy provides a new and promising method to selectively study the interfaces of microscopic structures.

Publications
"Effect of Bilayer Surface Charge Density on Molecular Adsorption and Transport Across Liposome Bilayers," Y. Liu, E.C.Y. Yan, and K.B. Eisenthal, Biophysical Journal, 80, 10041012 (2001)

"Ultrafast Solvation Dynamics at Silica/Liquid Interfaces Probed by Time-Resolved Second Harmonic Generation," X. Shang, A.V. Benderskii, and K.B. Eisenthal, J. Phys. Chem. B (2001)

"Aqueous Solvation Dynamics at the Anionic Surfactant Air/Water Interface," A.V. Benderskii and K.B. Eisenthal, J. Phys. Chem. B, 105, 6698 (2001)

"Static and Dynamic Solvation at the Air-Water Interface," D. Zimdars and K.B. Eisenthal, Accepted for publication in J. Phys. Chem. B, 105, 39934002 (2001)

"Protein Adsorption at Interfaces Detected by Second Harmonic Generation," J.S. Salafsky and K.B. Eisenthal, J. Phys. Chem. B, 104, 77527755 (2000)

"Second Harmonic Spectroscopy: Detection and Orientation of Molecules at a Biomembrane Interface," J.S. Salafsky and K.B. Eisenthal, Chem. Phys. Lett., 319, 435440 (2000)

"Probing the Interface of Microscopic Clay Particles in Aqueous Solution by Second Harmonic Generation ," E.C.Y. Yan and K.B. Eisenthal, J. Phys. Chem. B, 103, 60566060 (1999)

"Femtosecond Dynamics of Solvation at the Air/Water Interface," J. Dadap, D. Zimdars, T. Heinz, and K.B. Eisenthal, Chem. Phys. Lett., 301, 112120 (1999)

"Anisotropic Orientational Motion of Molecular Adsorbates at the Air-Liquid Interfaces," D. Zimdars, J. Dadap, T. Heinz, and K.B. Eisenthal, J. Phys. Chem. B, 103, 34253433 (1999)

"Study of Interfacial Charge Transfer Complex on TiO2 Particles in Aqueous Suspension by Second Harmonic Generation," Y. Liu, J. Dadap, D. Zimdars, and K.B. Eisenthal, J. Phys. Chem. B, 103, 24802486 (1999)

"Ultrafast Chemistry in Bulk Liquids and at Liquid Interfaces," K.B. Eisenthal, in Nobel Symposium Proceedings: Femtochemistry and Femtobiology: Ultrafast Reaction Dynamics at Atomic-Scale Resolution, ed. V. Sundstrim, Imperial College Press, London (1996)