Abnormal adsorption behavior of dimethyl disulfide on gold surfaces |
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Authors: | Jaegeun Noh Soonmin Jang Donghyung Lee Seokmin Shin Young Joon Ko Eisuke Ito Sang-Woo Joo |
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Institution: | 1. Department of Chemistry, Hanyang University, Seoul 133-791, Republic of Korea;2. Department of Applied Chemistry, Sejong University, Seoul 143-747, Republic of Korea;3. School of Chemistry, Seoul National University, Seoul 151-742, Republic of Korea;4. Department of Chemistry, Soongsil University, Seoul 156-743, Republic of Korea;5. Local Spatio-Temporal Functions Laboratory, Frontier Research System, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan |
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Abstract: | Adsorption of dimethyl disulfide (DMDS) on gold colloidal nanoparticle surfaces has been examined to check its binding mechanism. Differently from previous results, DMDS molecules adsorbed on the gold surface at high concentration showed the S–S stretching band at 500 cm−1 in surface-enhanced Raman scattering (SERS) spectra, which indicates the presence of intact adsorption of DMDS molecules. However, it was found that the S–S bond of disulfides was easily cleaved on the gold surface at low concentration. These behaviors were not observed for diethyl disulfide (DEDS) or diphenyl disulfide (DPDS). Our results indicate that DMDS molecules with the shortest alkyl chains on the gold surface can be inserted into self-assembled monolayers (SAMs) without the S–S bond cleavage during self-assembly due to insufficient lateral van der Waals interaction and the low adsorption activity of disulfides, whereas DEDS with longer alkyl chains or DPDS with the weak disulfide bond dissociation energy would not. These unusual DMDS adsorption behaviors were examined by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). We also compared the bonding dissociation energy of the S–S bonds of various disulfides by means of a density functional theory (DFT) calculation. |
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Keywords: | Adsorption Dimethyl disulfide Au SERS STM XPS |
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