Surface Propensity and Electric Fields at the Air/Water Interface: Water, Ions, and Lipids
Event details
| Date | 28.05.2014 |
| Hour | 10:00 |
| Speaker | Prof. Heather Allen, Ohio State University, Columbus, OH (USA) |
| Location | |
| Category | Conferences - Seminars |
BIOENGINEERING SEMINAR
Abstract:
Elucidating interfacial ion distributions, ion surface propensity, and hydration are of interest for environmental and materials applications including atmospheric aerosol chemistry, thundercloud electrification, material contamination, and corrosion processes. Heterodyne detected sum frequency generation (HD-SFG) and conventional vibrational SFG spectroscopies are used to understand anion versus cation air-aqueous interfacial distributions. Surface potential measurements also provide surface electric fields as does HD-SFG. Ion valency, polarizability, size, shape, and identity of the counterion are critical factors in considering ion organization and subsequent changes in interfacial electric field at the air -water interface. Here a series of mono and polyatomic anions and mono and divalent cations are compared using these methods. We observe that while polarizability and size of ions are important factors, hydration effects predominately drive interfacial behaviors. This is exemplified by magnesium and sulfate salt systems. In addition, work on phospholipids and fatty acids are also studied using both SFG and Brewster angle microscopy (BAM). Head group differences, especially with regard to hydrogen bonding capability and extent, are discerning factors for surface organization.
Bio:
Professor Allen received her B.S. degree in Chemistry in 1993 and Ph.D. in Physical Chemistry in 1997 at the University of California Irvine. Her advisors as an undergraduate, graduate, and postgraduate were Nobel Laureate F. S. Rowland, D. Blake, J. C. Hemminger, B. J. Finlayson-Pitts, and G. L. Richmond respectively. As a student and postdoctoral researcher she was awarded several fellowships including Fannie and John Hertz, EPA, an NSF Traineeship, and a NOAA Post-Doctoral Fellowship in Climate and Global Change. At Ohio State she has been recognized for her research accomplishments with a Research Innovation Award from Research Corp. in 2001, an NSF CAREER Award in 2002, a Beckman Young Investigator Award in 2003, an Alfred P. Sloan Research Fellow Award in 2005, a Camille Dreyfus Teacher-Scholar Award in 2006, and a Fellow of the American Association for the Advancement of Science (AAAS) in 2012. Dr. Allen has also been recognized for several mentoring awards over the years including the most recent in 2013, the American Chemical Society National Award for Encouraging Women into Careers in the Chemical Sciences. She is a Full Professor in the Department of Chemistry and Biochemistry and in the Department of Pathology, and her research specialization is in molecular organization at interfaces.
Abstract:
Elucidating interfacial ion distributions, ion surface propensity, and hydration are of interest for environmental and materials applications including atmospheric aerosol chemistry, thundercloud electrification, material contamination, and corrosion processes. Heterodyne detected sum frequency generation (HD-SFG) and conventional vibrational SFG spectroscopies are used to understand anion versus cation air-aqueous interfacial distributions. Surface potential measurements also provide surface electric fields as does HD-SFG. Ion valency, polarizability, size, shape, and identity of the counterion are critical factors in considering ion organization and subsequent changes in interfacial electric field at the air -water interface. Here a series of mono and polyatomic anions and mono and divalent cations are compared using these methods. We observe that while polarizability and size of ions are important factors, hydration effects predominately drive interfacial behaviors. This is exemplified by magnesium and sulfate salt systems. In addition, work on phospholipids and fatty acids are also studied using both SFG and Brewster angle microscopy (BAM). Head group differences, especially with regard to hydrogen bonding capability and extent, are discerning factors for surface organization.
Bio:
Professor Allen received her B.S. degree in Chemistry in 1993 and Ph.D. in Physical Chemistry in 1997 at the University of California Irvine. Her advisors as an undergraduate, graduate, and postgraduate were Nobel Laureate F. S. Rowland, D. Blake, J. C. Hemminger, B. J. Finlayson-Pitts, and G. L. Richmond respectively. As a student and postdoctoral researcher she was awarded several fellowships including Fannie and John Hertz, EPA, an NSF Traineeship, and a NOAA Post-Doctoral Fellowship in Climate and Global Change. At Ohio State she has been recognized for her research accomplishments with a Research Innovation Award from Research Corp. in 2001, an NSF CAREER Award in 2002, a Beckman Young Investigator Award in 2003, an Alfred P. Sloan Research Fellow Award in 2005, a Camille Dreyfus Teacher-Scholar Award in 2006, and a Fellow of the American Association for the Advancement of Science (AAAS) in 2012. Dr. Allen has also been recognized for several mentoring awards over the years including the most recent in 2013, the American Chemical Society National Award for Encouraging Women into Careers in the Chemical Sciences. She is a Full Professor in the Department of Chemistry and Biochemistry and in the Department of Pathology, and her research specialization is in molecular organization at interfaces.
Practical information
- Informed public
- Free