title: Atmospheric oxidation and carbon contamination of silver and its effect on surface-enhanced Raman spectroscopy (SERS).
abstract: Surface-enhanced Raman spectroscopy (SERS) is considered a highly promising technology for different analytical purposes. The applications of SERS are still quite limited due its relatively poor quantitative repeatability and the fact that SERS is very sensitive to oxidation, which is a challenge especially with silver based SERS substrates. Here, the link between these phenomena is investigated by exposing silver SERS substrates to ambient laboratory air. We show that SERS intensity decreases exponentially after the exposure, which consequently leads to an increasing standard deviation (σ) in intensity. Within a five-hour measurement window, the SERS intensity already drops by 60%, while σ triples from 7% to 21%. The SERS results are supplemented by elemental analysis, which shows that oxidation and atmospheric carbon contamination coincide with the rapid SERS intensity decrease. The results emphasize how sensitive SERS is towards atmospheric contamination and how it can also reduce the measurement repeatability - even if the substrates are exposed to air just for a very short period of time.
authors.affiliation: Institute of Photonics, University of Eastern Finland, Joensuu, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Matikainen
authors.affiliation: Institute of Photonics, University of Eastern Finland, Joensuu, Finland.|Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland.
authors.forename: Tarmo
authors.initials: T
authors.lastname: Nuutinen
authors.affiliation: Institute of Photonics, University of Eastern Finland, Joensuu, Finland.
authors.forename: Tommi
authors.initials: T
authors.lastname: Itkonen
authors.affiliation: Center of Microscopy and Nanotechnology, University of Oulu, Oulu, Finland.
authors.forename: Santtu
authors.initials: S
authors.lastname: Heinilehto
authors.affiliation: Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Puustinen
authors.affiliation: VTT Technical Research Centre of Finland, Oulu, FI-90590 Finland.
authors.forename: Jussi
authors.initials: J
authors.lastname: Hiltunen
authors.affiliation: Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland.
authors.forename: Jyrki
authors.initials: J
authors.lastname: Lappalainen
authors.affiliation: VTT Technical Research Centre of Finland, Oulu, FI-90590 Finland.
authors.forename: Pentti
authors.initials: P
authors.lastname: Karioja
authors.affiliation: Institute of Photonics, University of Eastern Finland, Joensuu, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Vahimaa