STM Image Analysis Of Polymers Simplified

Scientists at the Naval Research Laboratory have developed a simple procedure by which scanning tunneling microscopy (STM) can be used to record atomic-resolution images of polymers and other large molecules (Surf. Sci. 2008, 602, 3). Typically, researchers must choose between vacuum or ambient conditions. Vacuum conditions lead to favorable imaging and maintain sample cleanliness but complicate sample handling; ambient conditions simplify experiments but can deteriorate image quality. To overcome these trade-offs, Arnaldo R. Laracuente and coworkers prepared a hydrogen-terminated silicon crystal under vacuum. They deposited a solution-phase analyte (a pentiptycene-based copolymer) onto the crystal, which serves as a support and reference for structure analysis, and then returned the crystal to high vacuum and recorded polymer images. Chemist John J. Boland of Trinity College Dublin says the beauty of this approach is that it eliminates the need for sophisticated sample-delivery systems yet provides the full benefits of vacuum-based STM imaging.