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Heather Allen

Heather Allen

Heather Allen

Dow Professor, Ohio State Distinguished Scholar



3105 Newman & Wolfrom Laboratory
100 W 18th Ave
Columbus, OH 43210

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Areas of Expertise

  • Physical
  • Analytical
  • Environmental

Divisional Affiliation: Physical, Analytical, Biochemistry, Chemical Physics, Environmental



Professor Heather C. Allen attended Saddleback College from 1989-1992, completing much of her undergraduate science and general education coursework before transferring to the University of California, Irvine in 1992.  After her second year at Saddleback, she focused on the sciences, targeting chemistry as her major, winning a Saddleback College Science Scholarship Award to continue advancement toward her chemistry degree.  She received her B.S. degree in Chemistry in 1993, and Ph.D. in Physical Chemistry in 1997 at the University of California Irvine working with Nobel Laureate Sherwood Rowland and Don Blake as an undergraduate, and as a graduate student with John Hemminger and Barbara Finlayson-Pitts. She continued her postdoctoral studies in 1997 at the University of Oregon advised by Geraldine Richmond. Following the Saddleback Science Scholarship, as a student and postdoctoral researcher, she was also recognized with and by the Fannie and John Hertz Fellowship, EPA, NSF Traineeship, and a NOAA Post-Doctoral Fellowship in Climate and Global Change. 

Dr. Allen began her professorial career at Ohio State University in 2000, and has since been recognized for many research accomplishments, most recently the 2022 American Chemical Society Irving Langmuir Award in Chemical Physics for her cumulative work on liquids. Her prior awards include the Ohio State Distinguished Scholar Award, the Alexander von Humboldt Research Award from Germany, Alfred P. Sloan Research Fellow Award, Camille Dreyfus Teacher-Scholar Award, Fellow of the American Association for the Advancement of Science (AAAS), Research Innovation Award from Research Corp., NSF CAREER Award, and a Beckman Young Investigator Award.

Dr. Allen also has been recognized for several mentoring awards including the American Chemical Society National Award for Encouraging Women into Careers in the Chemical Sciences, an Empowered Woman Award from the City of Columbus, and an Ohio State Office of Minority Affairs Mentor Award.  She is a Full Professor in the Department of Chemistry and Biochemistry, and in the Department of Pathology.  

Research Overview

Dr. Allen’s research specialization is in interfacial phenomena, molecular organization, ions, ion pairing, and hydration at aqueous interfaces. Investigations of molecular organization and orientation, and chemical reaction mechanisms at gas - liquid, gas - solid, and liquid - solid interfaces are of interest. Laboratory experiments are designed to further understand organization of solvated ions and molecules such as water, lipids, and fatty acids and complexation at liquid surfaces and interfaces of biological and environmental relevance.

The Allen group utilizes and designs optical spectroscopic instruments and studies liquids and “soft” surfaces to understand fundamental processes. Applications range from ocean and atmospheric aerosol chemistry, thundercloud electrification, geochemistry, cell membrane organization, and lung lining surfactant systems. 

Dr. Allen was first to design the broadband vibrational sum frequency generation (BB-VSFG) system specifically for use on liquid surfaces. (Anal. Sci. 2001, 17(11), 1325-1329; and Anal. Sci. 2001, 17(1), 137-139.) BB-VSFG, since simplified to one femtosecond amplifier, is now common-place in VSFG laboratories. VSFG is inherently interface-selective and provides molecular-level interfacial information that includes relative orientation and structure of the surface species, i.e. the surface signature. 

In addition to VSFG, an array of analytical optical spectroscopic and interfacial tools is incorporated to fully understand the heterogeneous chemical processes at an interface. The Allen lab also has expertise in and uses Second Harmonic Generation, Polarized Raman Spectroscopy, Infrared Reflection Spectroscopies, Brewster Angle Microscopy and Surface Potential and Surface Tension Instrumentation. 

Previous Allen group members have positions in industry, national laboratories, and academia: Battelle Corporation, Intel, American Regent, Procter and Gamble, Spartan Chemical, OSU Surface Science Facility, Syngenta, Nestle, PPG Technologies, KLA Tencor, Chemical Abstracts Service, Canadian Synchrotron Facility, United States Geological Survey (USGS), Naval Research Lab (NRL), Pacific Northwest National Laboratory (PNNL), National Center for Atmospheric Research (NCAR), and professor positions at Hebei University in Baoding, China, Ohio Wesleyan University, and University of Findlay.

>Dr. Allen is accepting new graduate students that have interest in studying ion and molecular processes at aqueous surfaces using Sum Frequency, Second Harmonic, Raman, infrared, surface potential and surface tension methods. Graduate students from physical and analytical chemistry, chemical physics, environmental, and biophysics divisions are encouraged to request a meeting to discuss research. Detailed research information can be found on the Allen Group website.



A complete list of Allen Group's publications is available.

(Selected Publications)

Sodium Drives Interfacial Equilibria for Semi-Soluble Phosphoric and Phosphonic Acids of Model Sea Spray Aerosol Surfaces, ACS Earth and Space Chemistry, J. F. Neal, M. M. Rogers, M. A. Smeltzer, K. A. Carter-Fenk, A. J. Grooms, M. M. Zerkle, H. C. Allen; https://doi.org/10.1021/acsearthspacechem.0c00132 (2020).

Thermodynamic Signatures of the Origin of Anti-Hofmeister Selectivity for Phosphate at Aqueous Interfaces, A. J. Grooms, J. F. Neal, K. C. Ng, W. Zhao, A. H. Flood, H. C. Allen; J. Phys. Chem. A (2020)124, No27, July 9.

Iron(III) Speciation Observed at Aqueous and Glycerol Surfaces: Vibrational Sum Frequency and X-Ray,   L. Lin, J. Husek, Jakub; S. Biswas, S. Baumler, T. Adel, K. C. Ng, L. R. Baker, H. C. Allen; J. Am. Chem. Soc. (2019) 141, 34, 13525-13535.

Hydration of Ferric Chloride and Nitrate in Aqueous Solutions: Water-mediated Ion Pairing Revealed by Raman Spectroscopy, S. M. Baumler, W. H. Hartt V, H.C. Allen; Phys. Chem. Chem. Phys. (2019) DOI: 10.1039/C9CP01392J.

Molecular-level origin of the carboxylate head group response to divalent metal ion complexation at the air-water interface, J.K. Denton, P. J. Kelleher, M. D. Baer, S. M. Kathmann, C. J. Mundy, B. A. Wellen Rudd, H. C. Allen, T. H. Choi, K D.ordan, and M. A. Johnson; Proc. Natl. Acad. Sci. USA (2019), V116 (30), 14874-14880.

Interfacial Supramolecular Structures of Amphiphilic Receptors Drive Aqueous Phosphate Recognition; J. F. Neal, W. Zhao, A. J. Grooms, M. A. Smeltzer, B. M. Shook, A. H. Flood, H. C. Allen;   J. Am. Chem. Soc.  (2019) V141, 7876-7886 10.1021/jacs.9b02148 .

W. Hua,  X. Chen, H.C. Allen; Phase-Sensitive Sum Frequency Revealing Accommodation of Bicarbonate Ions, and Charge Separation of Sodium and Carbonate Ions within the Air/Water Interface, J. Phys. Chem. A 2011, 115, 6233-6238; (Memorial Issue for Victoria Buch). pdf

C. Y. Tang, Z. Huang, H. C. Allen; Interfacial Water Structure and Effects of Mg2+ and Ca2+ Binding to the COOH Headgroup of Palmitic Acid Monolayer Studied by Vibrational Sum Frequency Generation Spectroscopy, J Phys Chem B. 2011 Jan 13;115(1):34-40. pdf

X. Chen, W. Hua, Z. Huang, H. Castada, H. C. Allen; Reorganization and Caging of DPPC, DPPE, DPPG, and DPPS Mono layers Caused by Dimethylsulfoxide Observed Using Brewster Angle Microscopy, Langmuir, 2010, 26 (24), pp 18902-18908. pdf

M. R. Sierra-Hernandez and H. C. Allen, Incorporation and Exclusion of Long Chain Alkyl Halides in Fatty Acid Monolayers at the Air-Water Interface, Langmuir, 2010, 26 (24), pp 18806-18816. pdf

X. Chen and H. C. Allen, Water Structure at Aqueous Solution Surfaces of Atmospherically Relevant Dimethyl Sulfoxide and Methanesulfonic Acid Revealed by Phase Sensitive Sum Frequency Spectroscopy, J. Phys. Chem. B, 2010, 114 (46), pp 14983-14988. pdf

PCCP Perspective: Shedding Light on Water Structure at Air-Aqueous Interfaces: Ions, Lipids, and Hydration; H. C. Allen, N. N. Casillas-Ituarte, M. R. Sierra-Hernandez, X. Chen, C. Y. Tang; Phys. Chem. Chem. Phys., 2009, 11, 5521-5852. pdf

Ionic Binding of K+ and Na+ to the Carboxylic Acid Head Group of Palmitic Acid in Monolayers using Vibrational Sum Frequency Spectroscopy; C. Y. Tang, H. C. Allen; J. Phys. Chem. A, 2009, 113, 7383-7393. -Benny Gerber Festschrift Issue- pdf

Surface Residence and Uptake of Methyl Chloride and Methyl Alcohol at the Air/Water Interface Studied by Vibrational Sum Frequency Spectroscopy and Molecular Dynamics; K. Harper, B. Minofar, M. R. Sierra-Hernandez, N. N. Casillas-Ituarte, M. Roeselova, H.C. Allen; J. Phys. Chem. A, 2009, 113, 2015-2024 -Max Wolfsberg Festschrift Issue- pdf

Dangling OD Confined in a Langmuir Monolayer, G. Ma, X. Chen, H. C. Allen*, J. Am. Chem. Soc., 2007; 129(45); 14053-14057. pdf

Observation of hydronium ions at the air-aqueous acid interface: Vibrational spectroscopic studies of aqueous HCl, HBr, and HI, L. M. Levering, M. R. Sierra-Hernández, H. C. Allen*, 2007, J. Phys. Chem. C, 111 (25), 8814-8826. pdf

Oxidation of oleic acid at air/liquid interfaces, Voss, L. F., M. F. Bazerbashi, C. P. Beekman, C. M. Hadad, and H. C. Allen*, J. Geophys. Res., 2007, 112, D06209, doi:10.1029/2006JD007677. pdf

New Insights into Lung Surfactant Monolayers using Vibrational Sum Frequency Generation Spectroscopy; G. Ma and H. C. Allen*; Photochemistry and Photobiology, 2006, V82, 1517-1529. pdf

DPPC Langmuir monolayer at the air-water interface: probing the tail and head groups by vibrational sum frequency generation spectroscopy, G. Ma & H.C. Allen*, 2006, Langmuir; 22(12); 5341-5349. pdf

Vibrational Spectroscopic Studies of Aqueous Interfaces: Salts, Acids, and Nanodrops, S. Gopalakrishnan, D. Liu, and H. C. Allen* and M. Kuo and M. J. Shultz*, Chemical Reviews, 2006, 106(4), 1155-1175. pdf

Air-Liquid Interfaces of Aqueous Solutions Containing Ammonium and Sulfate: Spectroscopic and Molecular Dynamics Studies, S. Gopalakrishnan, P. Jungwirth, D. J. Tobias, H. C. Allen*, J. Phys. Chem. B, 2005, V109 (18), 8861 - 8872. pdf

Unified Molecular Picture of the Surfaces of Aqueous Acid, Base, and Salt Solutions; M. Mucha, T. Frigato, L. M. Levering, H. C. Allen, D. J. Tobias, L. X. Dang, P. Jungwirth; J. Phys. Chem. B, 2005, 109, 7617 - 7623. pdf


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