Direct visualization of a surface-enhanced Raman spectroscopy nano-gap via electrostatic force microscopy: Dependence on charge transfer from the underlying surface nano-gap distance
- Authors
- Park, Won-Hwa; Park, Sung-Gyu; Kang, Mijeong; Hyun, Moon Seop; Choi, Namhyun; Kim, Dong-Ho; Choo, Jaebum
- Issue Date
- Jun-2019
- Publisher
- Elsevier B.V.
- Keywords
- Charge transfer; Electrostatic force microscopy; Nano-gap; Single molecule sensitivity; Surface-enhanced Raman scattering
- Citation
- Applied Surface Science, v.479, pp 874 - 878
- Pages
- 5
- Journal Title
- Applied Surface Science
- Volume
- 479
- Start Page
- 874
- End Page
- 878
- URI
- https://scholarworks.bwise.kr/cau/handle/2019.sw.cau/44771
- DOI
- 10.1016/j.apsusc.2019.02.034
- ISSN
- 0169-4332
1873-5584
- Abstract
- We have visualized surface-enhanced Raman scattering (SERS) nano-gap domains with electrostatic force microscopy (EFM). We constructed the SERS substrate using reactive-ion etching of a polyethylene terephthalate (PET) film, with subsequent sputtering of Au onto the etched PET. Because the nano-gap is more strongly charged than the native Au-nanoparticle (NP) surface, we can identify the SERS nano-gap due to the longer dwell time of the tapping EFM tip and the related phase shift of the signal. This produces a differentiating image contrast between the SERS nano-gap and the Au NP surface, with a spatial resolution of ~14 nm. More specifically, differences in the mode-independent Raman-signal enhancement and the peak shift of an adsorbed malachite green isothiocyanate (MGITC) molecule are only observed in the smaller SERS nano-gap (found in the surface with Ar + -sputtered Au nano-pillars). We interpret this in terms of the differing morphologies of the underlying Au substrates and the related mechanical compressive strains, which result in charge transfer (CT)-based single-molecule Raman-reporter detection sensitivity. © 2019 Elsevier B.V.
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