In this paper from University of Exeter, Thomas Read and co-workers determine the propagation of plasmon fields in biological media. They make as stack immunoglobulin molecules and determine the critical parameter (β for us who grew up with reading electron transfer literature) for a plasmonic gold surface and a gold nanoparticle. The numbers are 17.5 nm and 90 nm, respectively. As the number goes in the denominator in an exponential, this is a significant difference in the reach of the plasmon fields.
I find it enticing that, in a field dominated by physicists, a chemical approach using biomolecules is the experimentalists answer to measure the extent of the plasmon fields. By building a tower of molecules it is possible to see the step wise change in the read-out from the SPR platform. For a person outside the field, the paper contain an advert for the home-build LSPR platform the authors use in their experiments. The data from this set-up completely outshines the data from the commercial SPR platform.
If your curiosity has been aroused, the full paper is published in PCCP under the title:
Measurement of the localised plasmon penetration depth for gold nanoparticles using a non-invasive bio-stacking method
Thomas Read, Rouslan V. Olkhov and Andrew M. Shaw
DOI: 10.1039/C3CP50758K
by Dr Thomas Just Sørensen
Between bulk metals and their individual atoms lies the murky world of metallic clusters. These often have unique properties, and understanding them is as challenging as it is interesting. Many properties are a direct function of cluster size, and provide important insights into the progression from individual atoms to bulk solids. It is therefore important to ascertain the exact size at which a particle ceases to be classified as a cluster and becomes a bulk solid. This moment can either be measured experimentally or calculated using a theoretical model.
