EN
Silver nanostructures are used in tip- and
surface-enhanced Raman spectroscopy due to their high
electric field enhancement over almost the entire visible
spectral range. However, the low chemical stability
of silver, compared to other noble metals, promotes
silver sulfide and sulfate formation which decreases
its plasmonic activity. This is why silver tips are usually
prepared on the same day of the experiments or are
disregarded in favour of gold that is chemically more
stable. Since silver degradation cannot be avoided, we
hypothesized that a protection layer may be able to
minimize or control degradation. In this contribution,
we report the successful preparation of 4-biphenylthiol
and 4’-nitro-4-biphenylthiol self-assembled monolayers
on silver tips in order to protect them against tarnishing
and to investigate the effect on the life-time of the
plasmonic activity. The electrochemically etched wire
surface was probed via Raman spectroscopy and scanning
electron microscopy. The best long term stability and
resistance against corrosion was shown by a monolayer
of 4-biphenylthiol formed from dimethylformamide
which did not display any degradation of the metallic tip
during the observed period. Here, we demonstrate an easy
and straightforward approach towards increasing the
chemical stability of silver TERS-active probes.