Abstract
We report the thickness and interfacial molecular structure of thin (1-3 nm) aqueous films supported on hydroxyl-terminated self-assembled monolayers over a silver substrate. The water film structure is studied as a function of varying the monolayer's methylene chain lengths. Analysis techniques include ellipsometry, contact angle, and polarization modulation reflection adsorption infrared spectroscopy. The aqueous film thicknesses follow 4-mercaptobutanol (4-MBU) > 11-mercaptoundecanol (11-MUD) > 6-mercaptohexanol (6-MHE) > 9-mercaptononanol (9-MNO). Water contact angle measurements across the same surfaces are very similar; however, vibrational spectroscopic analysis of the films shows that intermolecular bonding patterns of D2O are significantly different from those of bulk D2O. This evokes unique interfacial molecular architectures for each of these films. The structural differences depend on the nature of the SAM structure and resulting water-SAM interactions, which are evident from PM-IRRAS data. Spectroscopic peak intensity ratios of ν(O-D) modes suggest more asymmetric hydrogen-bonded D2O character near 9-MNO surfaces, whereas 4-MDU, 6-MHE, and 11-MUD surfaces exhibit increasingly symmetric hydrogen-bonded D2O character. From this, we propose a model for film structure.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
