Bias voltage-dependent STM−tip-enhanced Raman spectroscopy of benzenethiol-modified gold nanoplates

•Benzenethiol-modified gold nanoplates on graphite are measured under STM−TERS.•We study dependence of Raman and PL intensity on bias voltage.•Net enhancement spectra for gap-mode plasmons are obtained.•We find low bias voltage is appropriate for STM−TERS measurements.•We obtain the spatial distribution of the field enhancement by gap-mode plasmons.

We measured tip-enhanced Raman scattering (TERS) and photoluminescence (PL) spectra of benzenethiol-modified gold nanoplates fixed on graphite, by using a gold tip for scanning tunneling microscopy (STM) measurements. With increasing bias voltage between the tip and the nanoplates, the Raman intensities of benzenethiol gradually decreased, while the PL intensities decreased first and then increased. This implied that relatively low bias voltages are suitable for STM−TERS measurements. Both PL mapping and STM images of the nanoplates were simultaneously obtained. The PL mapping images showed that field enhancement by gap-mode plasmons between the tip and the nanoplates depended on their configuration.

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