title: "Atomic Force Masking" Induced Formation of Effective Hot Spots along Grain Boundaries of Metal Thin Films.
abstract: We present an interesting phenomenon, "atomic force masking", which is the deposition of a few-nanometer-thick gold film on ultrathin low-molecular-weight (LMW) polydimethylsiloxane (PDMS) engineered on a polycrystalline gold thin film, and demonstrated the formation of hot spot based on SERS. The essential principle of this atomic force masking phenomenon is that an LMW PDMS layer on a single crystalline grain of gold thin film would repel gold atoms approaching this region during a second cycle of evaporation, whereas new nucleation and growth of gold atoms would occur on LMW PDMS deposited on grain boundary regions. The nanostructure formed by the atomic force masking, denoted here as "hot spots on grain boundaries" (HOGs), which is consistent with finite-difference time-domain (FDTD) simulation, and the mechanism of atomic force masking were investigated by carrying out systematic experiments, and density functional theory (DFT) calculations were made to carefully explain the related fundamental physics. Also, to highlight the manufacturing advantages of the proposed method, we demonstrated the simple synthesis of a flexible HOG SERS, and we used this substrate in a swabbing test to detect a common pesticide placed on the surface of an apple.
authors.affiliation: Department of Materials Science and Engineering, Yonsei University , Seoul 03722, South Korea.
authors.forename: Kwang Hyun
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT) , Daejeon 34114, South Korea.
authors.forename: Soo Sang
authors.initials: SS
authors.lastname: Chae
authors.affiliation: Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT) , Daejeon 34114, South Korea.
authors.forename: Seunghun
authors.initials: S
authors.lastname: Jang
authors.affiliation: Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT) , Daejeon 34114, South Korea.|Materials and Science Engineering Department, University of Michigan , Ann Arbor, Michigan 48109, United States.
authors.forename: Won Jin
authors.initials: WJ
authors.lastname: Choi
authors.affiliation: Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT) , Daejeon 34114, South Korea.
authors.forename: Hyunju
authors.initials: H
authors.lastname: Chang
authors.affiliation: Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT) , Daejeon 34114, South Korea.
authors.forename: Jeong-O
authors.initials: JO
authors.lastname: Lee
authors.affiliation: Department of BioNano Technology, Gachon University , Seongnam, Gyeonggi-Do 13120, South Korea.
authors.forename: Tae Il
authors.initials: TI
authors.lastname: Lee
keywords: Raman; SERS; gold nanoparticle; hot spot; nanogap