Presentation Information
[24a-61A-1]Optical and defect control in WO3-x films for charge transfer-based SERS applications
〇(M2)Yan Ding1, Jiaqi Yang1, Tang Dang1, Hitoshi Tabata1, Hiroaki Matsui1 (1.The Univ. of Tokyo)
Keywords:
SERS,Oxygen vacancy,WO3-x
Surface-enhanced Raman spectroscopy (SERS) is a cutting-edge method renowned for its high sensitivity in molecular fingerprinting and trace detection. This method primarily relies on an electromagnetic (EM) process via a localized surface plasmon resonance (LSPR). To date, SERS has received much attention on metallic nanostructures, such as Au and Ag, for their strong LSPRs. However, the advantage of plasmonic resonances causes local heating effects, which produce unwanted side effects of SERS detection. This has demonstrated a change in local temperature at nanogaps in Au and Ge nanoparticle dimers. As an alternative, semiconductor materials like defective TiO2 and MoO3 have been chosen for SERS applications based on chemical (CM) enhancement through a charge transfer (CT) process between Raman-active molecules and the substrate. Despite this shift, semiconductors with a simple synthesis process have yet to achieve the enhancement levels of their noble metal counterparts.
Our presentation introduces the novel application of non-stoichiometric tungsten oxide (WO3-x) thin film as a SERS substrate, aiming to enhance substrate-analyte interactions and optimize the CT process. WO3-x thin films, which were fabricated by the pulsed laser deposition (PLD), efficiently generate large amounts of oxygen vacancies in the host during PLD film growth. The non-stoichiometric films demonstrate strong visible absorption, which showed highly sensitive SERS compared to that of a stoichiometric film. This result indicates that the introduction of oxygen vacancies caused by the film growth conditions promotes the photoinduced CT resonance between analytes and substrate due to the matching energy levels of adsorbed probe molecules and the semiconductor. The achieved detection limit concentration was estimated as 10−6 M, and the maximum enhancement factor (EF) reached 2 × 106.
Our presentation introduces the novel application of non-stoichiometric tungsten oxide (WO3-x) thin film as a SERS substrate, aiming to enhance substrate-analyte interactions and optimize the CT process. WO3-x thin films, which were fabricated by the pulsed laser deposition (PLD), efficiently generate large amounts of oxygen vacancies in the host during PLD film growth. The non-stoichiometric films demonstrate strong visible absorption, which showed highly sensitive SERS compared to that of a stoichiometric film. This result indicates that the introduction of oxygen vacancies caused by the film growth conditions promotes the photoinduced CT resonance between analytes and substrate due to the matching energy levels of adsorbed probe molecules and the semiconductor. The achieved detection limit concentration was estimated as 10−6 M, and the maximum enhancement factor (EF) reached 2 × 106.