Structural
and Charge Sensitivity of Surface-Enhanced
Raman Spectroscopy of Adenine on Silver Surface: A Quantum Chemical
Study
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Abstract
The interaction of adenine with silver
surfaces has been investigated
using density functional method. Two isomers of N9H and N7H were included
to model surface species. Considering the complexity of silver surfaces
in surface-enhanced Raman spectroscopy, neutral and positive silver
clusters were used to mimic the substrate. Following the bonding principle,
we consider adenine-approached silver clusters in different configurations
and their relation to the Raman spectra. For neutral adenine Ag<sub><i>n</i></sub> (<i>n</i> = 4, 7, and 9) complexes,
N9H–Ag<sub><i>n</i></sub> complexes are more stable
than N7H–Ag<sub><i>n</i></sub> ones. The corresponding
Raman spectra strongly depended on the structure of adenine and the
adsorption sites. Moreover, we find N7H interacts with one positively
charged silver cluster via N3 and N9 at the same time as the most
stable surface complex, which can reproduce the experimental surface
Raman spectra of adenine well on silver surfaces