The funding for our current research projects are provided by National Science Foundation (Award No. 1808468), the Department of Chemistry, Indiana Academy of Science Senior Research Grants, and Ball State University

We Study Chemical Processes at Various Interfaces

Pioneered by the respective works of Paul Sabatier and Fritz Haber on catalytic hydrogenation and nitrogen fixation in the presence of finely divided metal surfaces, and through the seminal contributions made by Irving Langmuir, the scientific genre known as surface science came to existence in the early to mid 1900s. Throughout its long history and especially in the last three decades, owing to various scientific breakthroughs, surface science has experienced a rapid growth and has evolved into one of the most comprehensive and indispensable field of science. Surface science entails the understanding of all natural processes – physical, chemical, and biological, that occurs at the interface of two phases, rendering it a truly interdisciplinary field. For surfaces are everywhere in nature, obtaining the knowledge of these interfacial phenomena, such as adsorption, photochemistry, and spectroscopic properties of adsorbed chemical species, is thus not only vital but also of widespread practical interest. In our group we explore interfacial phenomena at various surfaces relevant to (1) nanotechnology, (2) environmental pollution, and (3) atmospheric/aerosol science. We use traditional spectroscopic techniques and an advanced laser spectroscopy, second harmonic generation (SHG), to probe surface chemistry at a molecular level.

Surface Selective Laser Spectroscopy –  SHG

The second order nonlinear spectroscopy (NLS) involves a simultaneous interaction between a molecule and two photons of high intensity. The result is the generation of a new photon oscillating at a sum frequency of the two incident photons. When the two incident photons have the same frequency, i.e., w1 = w2 = w, the output signal is a second harmonic generation (SHG) at 2w. The detected SHG signal contain information about the chemical interface and the surface bound molecules.

Research Theme I –  Environmental Pollution Transport and Fate

The goal of this research project is to study how organic pollutants interact with the surface of different types of colloids dispersed in aqueous solution. Fundamental understanding of molecular interaction with the surface of particle is essential to understand transport and fate of anthropogenic contaminants in aquatic system. Knowledge of binding efficiencies will provide insight in to surface adsorption as a pollution remediation technique.

Research Theme II –  Nanochemistry

With the need for high energy consumption for developing countries and concurrently with growing concerns of global climate change and increasing volatility in the oil prices, it has become necessary to shift to a cost-effective, renewable, highly-efficient and environmentally-friendly energy source. The goal of this project is to survey the interfacial properties of an array of sensitized nanoparticle applicable to the development of solar cells in a systematic way to determine the effectiveness of nanoparticles as a functioning solar cell.

Research Theme III –  Atmospheric Surface Science

Aerosols are mixtures of solid or liquid particles suspended in air.  They can range from few nanometers to a few tens of micrometers in size and thus provide a large surface area for interfacial chemistry to take place. At present there is insufficient kinetic data and no mechanism for the modeling of atmospheric reactions of VOCs and aromatic compounds with aerosols in photochemical oxidation or other reaction systems. To better understand the impact of aerosols on overall atmospheric processes, knowledge of aerosol surface chemistry is essential. Our current focus is to understand: (1) uptake of atmospheric pollutants to heterogeneous aerosol mixtures (2) adsorption and co-adsorption of volatile organic compounds (3) chemical reactivity at gas/aerosol interfaces and (4) spectral identification of heterogeneous aerosol composition.