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Details of Grant 

EPSRC Reference: EP/J002534/2
Title: Dynamics of Gas-Liquid Reactions; The Pseudo-Surface Approach
Principal Investigator: Greaves, Dr SJ
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Sch of Engineering and Physical Science
Organisation: Heriot-Watt University
Scheme: Career Acceleration Fellowship
Starts: 01 October 2012 Ends: 30 September 2016 Value (£): 896,295
EPSRC Research Topic Classifications:
Surfaces & Interfaces
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
Chemical reactions require a collision between two chemical species, and have been widely developed and exploited in solution by synthetic chemists to make a variety of products such as plastics and drugs. Chemical interactions are studied in greater detail by physical chemists, who often work with gases in order to isolate individual molecular collisions for quantitative study. However the fundamental dynamics of dual-phase (gas-liquid) interactions are poorly understood and, to date, have received only limited attention. Gas-liquid interactions are of particular importance to a wide variety of physical processes, ranging from respiration in living organisms (which relies on uptake of oxygen from air, into the blood) to distillation, gas chromatography, and atmospheric chemistry at the surfaces of aerosol particles (where for example water droplets in air can absorb sulfuric acid to from acid rain) and the Earth's oceans.

The aim of the proposed research is to improve the fundamental understanding of gas-liquid surface interactions by employing a novel experimental strategy; using a large, but volatile, flexible molecule as a simplified proxy for a liquid surface (a pseudo-surface). This will allow chemical reactions that occur at the gas-liquid interface to be studied in unprecedented detail using high resolution laser based techniques coupled with imaging methods. The imaging allows pictures to be taken of the fate of products of a chemical reaction, which will allow us to develop in-depth understanding of the mechanisms involved.

This project will focus on the construction and use of a unique, compact imaging experiment that will be the first of its kind in the UK. Using the experiment we can measure the direction and speed with which any products of reactions fly. This will allow us to gain in-depth knowledge of the different possible reaction mechanisms of collisions of molecules with pseudo-surfaces. The simplest pathway is a single collision reaction, called a direct mechanism. Some colliding atoms or molecules are trapped on the surface, however, undergoing multiple collisions before reacting (a so called trapping-desorption mechanism), and in extreme cases the pseudo-surface adsorbs the other reagent. The football / apple tree analogy is helpful here: imagine if you kick a football into an apple tree, it could come out straight away, bouncing off a branch, bringing an apple with it (direct mechanism), or it could get temporarily caught bouncing from branch to branch before leaving with an apple (trapping-desorption), or it could become wedged between the branches. The work proposed here will study the football and apple tree problem in detail and use it as a model to investigate the football and orchard problem (the real liquid, where lots of identical molecules (apple trees) make up the surface). This analogy can be extended to use rugby and other shaped balls to represent different incoming atoms/molecules/radicals that we intend to study.

The research will have a profound impact on the understanding of surface interactions, and will be of benefit to a broad community of researchers in Chemistry, Physics, Engineering, and ultimately Life Sciences, with interest in gas-liquid interfaces.

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Organisation Website: http://www.hw.ac.uk