Investigation of Polar Organic Adsorption/desorption from a Model Carbonaceous Surface: Acetone on Graphite

Optical techniques have been widely shown to be convenient, in-situ, and real time methods to investigate surface processes.[1] Compared with conventional surface probes, such as ion and electron spectroscopy, optical techniques are useful over a wide range of ambient conditions.[2-4] This study reports the adsorption and desorption of a model adsorbent representative of a volatile polar organic compound (acetone) on a model carbonaceous surface (HOPG). Many environmental phenomena involving carbonaceous surfaces occur under conditions where standard UHV surface science techniques cannot be applied, e.g., atmospheric pressure. ODR and TPD experiments were performed and showed that the strong correlation between ODR, determined in real time, and relative surface coverage, determined a posteriori by TPD for metal systems could also be extended to carbonaceous surfaces. Thus, we established that ODR could be used quantitatively to determine coverage on carbonaceous surface under conditions where TPD cannot be employed.