High sensitivity surface enhanced Raman spectroscopy of R6G on in situ fabricated Au nanoparticle/graphene plasmonic substrates |
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| Affiliation: | 1. Department of Physics & Astronomy, University of Kansas, Lawrence, KS 66045, USA;2. Department of Electrical Engineering & Computer Science, University of Kansas, Lawrence, KS 66045, USA;1. College of Physics and Electronics, Shandong Normal University, Jinan, 250014, People''s Republic of China;2. College of Physics and Electronic Information, Dezhou University, Dezhou, 253023, People''s Republic of China;3. State Key Lab of Crystal Materials Shandong University, Jinan, 250100, People''s Republic of China;1. School of Physics and Optoelectronic Engineering, Ludong University, Yantai, China;2. School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, China;3. Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, China;4. Laser Optics Research Center, Physics Department, United States Air Force Academy, CO, USA |
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| Abstract: | Plasmonic gold nanoparticles (AuNP) with controllable dimensions have been fabricated in situ on graphene at moderately elevated temperature for high sensitivity surface enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) dye molecules. Significantly enhanced Raman signature of R6G dyes were observed on AuNP/graphene substrates as compared to the case without graphene with an improvement factor of 400%, which is remarkably greater than previous results obtained in ex situ fabricated SERS substrate. Simulation of localized electromagnetic field around AuNPs with and without the underneath graphene layer reveals an enhanced local electromagnetic field due to the plasmonic effect of AuNPs, while additional Ohmic loss occurs when graphene is present. The enhanced local electromagnetic field by plasmonic AuNPs is unlikely the dominant factor contributing to the observed high SERS sensitivity on R6G/AuNP/graphene substrate. Instead, the p-doped graphene, which is supported by the large positive Dirac point shift away from “zero” observed in AuNP/graphene field effect transistors, promotes SERS signals through enhanced molecule adsorption and non-resonance molecular–substrate chemical interaction. |
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