M. Sc. Sefa Akca
Supervisors: Ralf Riedel, Norbert Nicoloso
This project aims to further the understanding of gas kinetics on surfaces, specifically the detection of adsorbing and desorbing molecules. In the field of gas sensing, electrical measurements, specifically conductance changes of the substrate are correlated with surface kinetics due to the charge transfer between substrate and adsorbent and provide very high quantitative sensitivity . However, this approach fails to provide qualitative information. To this end, this project proposes to the use MIR Spectroscopy in combination with a graphene transistor substrate in order to fill the gap in qualitative analysis. Graphene with its very high theoretical surface area and incredible electronic properties, is an ideal substrate to use in gas sensing.
To realize this idea, time-resolved MIR Reflection Spectroscopy as well as MIR Ellipsometry are utilized. Time evolution of the adsorbents MIR finger-print characteristics yield both quantitative and qualitative information . These results are then also correlated with simultaneous conductance measurements from the graphene substrate.
 A. Gurlo, and R. Riedel, “In Situ and Operando Spectroscopy for Assessing Mechanisms of Gas Sensing”, Angew. Chem. Int. Ed., 46, 3826-3848 (2007).
 Fonseca, A. A., Gardner, P., Torbati, R., Sakakini, B. H., & Waugh, K. C. (2004). The determination of desorption rate constants by monitoring of the time dependence of the decay of infrared bands – Dynamic infrared spectroscopy. Journal of Catalysis, 221(2), 313–318.