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Ultra-high vacuum scanning tunneling microscopy (UHV-STM) was used to investigate two related molecules pulse-deposited onto Au(111) surfaces: indoline-2-carboxylic acid and proline (pyrrolidine-2-carboxylic acid). 

Over the past decade, the trade of counterfeit goods has increased. This has been enabled by advancements in low-cost digital printing methods (e.g., inkjet and laserjet) that are an asset for counterfeit production methods. However, each printing method produces characteristic printed features that can be used to identify not only the printing method, but also, uniquely identify the specific make and model of printer. This knowledge can be used for determination of whether or not the analyzed item is counterfeit. During the first phase of this research, chemical and physical analyses were performed on printed documents and ink samples for two types of digital printing: inkjet and laserjet. The results showed that it is possible to identify the digital method used to print a document by its unique features. Physical analysis revealed that the laserjet prints have a higher image quality characterized by sharper feature edge quality, brighter image area, and a thicker ink layer (10 micron average thickness) than in inkjet documents. Chemical analysis showed that the inkjet and laserjet inks could easily be distinguished by identifying the various ink components. Ink jet inks included (among others) water, ethylene glycol while laserjet inks presented styrene, methacrylate, and sulfide compounds.