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Caption : figure s1. schematic energy band diagram of zno-ag interface of charge transfer from ec of zno to ef under 305 nm laser excitation, causing fluorescence quenching of zno

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Caption : figure s2: the frontier molecular orbitals (highest occupied molecular orbital (homo) and lowest unoccupied molecular orbital (lumo))  of two trans and cis isomers of mr molecule

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Caption : figure s3: (a) the optimized molecular structure of the cis isomer; (b) normalized raman spectra of methyl red in comparison between theoretical calculation study for neutral cis- and trans isomers

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Caption : figure s4: absorption spectra of mr in ethanol under different ph. the spectrum at ph 5.5 was obtained without needing any ph adjustment

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Caption : figure s5. fluorescence spectrum of mr under excitation wavelength at 500 nm

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Caption : figure s6: raman spectra of mr (10-2 m¬) under two different lasers excitation 532 nm and 785 nm

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Caption : figure s7: sers spectra of mr adsorbed on zno surface (a) in comparison with zno/ag surface; and (b) under different excitation wavelengths