This paper reports a handy technical scheme to decorate
atomic
force microscopy (AFM) tips toward tip-enhanced Raman spectroscopy
(TERS) applications. The major attraction of these homemade tips lies
in that silver decoration can be confined at the apex of commercial
tips by the means of an AFM-controlled electrochemical reaction. The
reduction of Ag+ occurs in a highly sealed environment
to secure the metal coating efficiency. Key factors include silver
nitrate solution to provide Ag+, ambient relative humidity
and temperature in a humidity cell, electric potential bias, and tip–surface
distance. Subsequently, these silver-coated tips are evaluated for
TERS measurement of carbon nanotubes (CNTs) so that both morphological
and chemical characteristics of CNTs are concurrently obtained. The
Raman spectra reveal that our plasmonic tip competently possesses
an ∼30-fold local field signal increase and the corresponding
TERS image laterally resolves at the single-pixel level.
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