We investigate the influence of the native staircase nanostructure of a Au(111) vicinal surface upon the self-assembly of alkylthiols. Through a comparison with standard alkylthiol SAMs deposited on Au(111) flat surfaces, we show that on the vicinal surface the octanethiol monolayer (OT SAM) reproduces the nanopatterned staircase structure, giving rise to a new kind of molecular layer self-ordered on the nanometer scale. The SAM's structure is determined by UHV STM and PM-IRRAS measurements and exhibits a specific behavior relative to the nanostructured substrate. The differences from the film grown on Au(111) are attributed to the influence of step edges on the molecular packing, leading to a specific 2D crystallographic order through the step edges.
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http://dx.doi.org/10.1021/la7031994 | DOI Listing |
Chemphyschem
September 2023
Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT, USA.
Photochromic molecules can undergo a reversible conversion between two isomeric forms upon exposure to external stimuli such as electromagnetic radiation. A significant physical transformation accompanying the photoisomerization process defines them as photoswitches, with potential applications in various molecular electronic devices. As such, a detailed understanding of the photoisomerization process on surfaces and the influence of the local chemical environment on switching efficiency is essential.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
April 2023
Department of Chemistry, College of the Holy Cross 1 College St., Worcester, Massachusetts 01610, United States.
A two-dimensional (2D) mixture in the form of a self-assembled monolayer composed of two distinct organothiol compounds was created by sequentially depositing 1-naphthalenethiol (1NT) and octanethiol (OT) on a gold surface. By varying the sequence of deposition, two mixed surface systems were created. The surface structure of the resulting mixed monolayer was characterized with Scanning Tunneling Microscopy (STM) and showed surface disorder across all investigated domains.
View Article and Find Full Text PDFSmall Methods
October 2022
KU-KIST Graduate School of Converging Science and Technology, Korea University, Seongbuk-gu, Seoul, 02841, Republic of Korea.
Solid-state devices capable of controlling light-responsive charge transport at the molecular scale are essential for developing molecular optoelectronic technology. Here, a solid-state molecular photodiode device constructed by forming van der Waals (vdW) heterojunctions between standard molecular self-assembled monolayers and two-dimensional semiconductors such as WSe is reported. In particular, two non-functionalized molecular species used herein (i.
View Article and Find Full Text PDFPesticides pose a great threat to human health and their rapid detection has become an urgent public safety issue engaging the scientific community to search for fast and reliable detection techniques. In this context, Surface Enhanced Raman Spectroscopy (SERS) has emerged as a valuable detection and analysis tool due to its high sensitivity and selectivity, proving its suitability for the food industry and environmental monitoring applications. Here, we report on the fabrication of colloidal silver nanoparticle (AgNP) films by convective self-assembly (CSA) on solid planar substrate and their use for the SERS analyses of two types of pesticides, the fungicide thiabendazole (TBZ) and the insecticide α-endosulfan (α-ES).
View Article and Find Full Text PDFJ Colloid Interface Sci
June 2022
Institute of Materials Science & Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland.
Surface modification of ligand protected nanoparticles (NPs) can be driven by ligand exchange reactions (LER). Little is known about the mechanism of this reaction, especially when the particles are not spherical. Here, we use the intrinsic hot spots generated on the corners/edges of 40 nm silver nanocubes (AgNCs) and the extrinsic hot spots generated by the aggregation of AgNCs to obtain strong enhancements in surface enhanced Raman scattering (SERS) to monitor the displacement of poly(vinylpyrrolidone) with either a hydrophilic (sodium 11-mercapto-1-undecanesulfonate, MUS) or a hydrophobic ligand (1-octanethiol, OT).
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