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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

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From micro to nano : analysis of surface-enhanced resonance Raman spectroscopy active sites via multiscale correlations

Khan, I. and Cunningham, D. and Littleford, R.E. and Graham, D. and Smith, W.E. and McComb, D.W. (2006) From micro to nano : analysis of surface-enhanced resonance Raman spectroscopy active sites via multiscale correlations. Analytical Chemistry, 78 (1). pp. 224-230. ISSN 0003-2700

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Effective correlation of data from a number of analytical techniques over length scales spanning several orders of magnitude is required to more fully investigate the active sites on silver nanoparticles that are responsible for surface-enhanced resonance Raman scattering (SERRS). In this paper, a method is presented that uses fluorescent beads as optical markers to allow direct correlation between a SERRS/fluorescence map and a transmission electron microscope (TEM) collage of the same area. Factors influencing the accuracy of the technique include the flatness of the substrate, the size of the fluorescent beads, and the strength of the signal from the fluorescent beads. When the effect of each of these factors on the technique is addressed, a simple and accurate correlation between the optical spectroscopy and the electron microscopy is achieved. A statistically significant number of particles can then be easily and reliably located and characterized at both optical limits, by SERRS, and with subnanometer resolution in the high-resolution TEM. Examples of HRTEM images and the locations of these particles within the SERRS map/TEM collage are presented. Our findings reveal that the relative SERRS activity of single particles is very low compared to dimers and larger aggregates of particles. The relative activity of dimers is estimated to be 12.4 times greater than single particles, and as the number of particles in the aggregate increase, the relative SERRS activity also increases. The relative SERRS activities of single particles/dimers/trimers/aggregates of 4-9 particles/aggregates of 10-20 are estimated to be 1/12.4/15.6/23.2/43.