In our ongoing effort to build partnerships and linkages that enhance academic interaction in the research community, Perimeter Institute is pleased to be hosting the Guelph-Waterloo Physics Institute (<G|W>) Distinguished Lecture on November 29, 2007. The Distinguished Lecture, entitled Surface-Enhanced Raman Spectroscopy and its Progeny will be given by Dr. Martin Moskovits of the Department of Chemistry and Biochemistry, and California Nanosystems Institute, University of California, Santa Barbara (UCSB) and CTO, API Nanotronics Corporation. His research interests have ranged widely over much of physical chemistry including spectroscopy, surface chemistry, and more recently the chemistry and fabrication of materials. For more information about the speaker, click here.
For more information about the <G│W> Physics Institute and the Distinguished Lecture, click here.
This lecture is available to all university students and professors from surrounding institutions.
Some thirty years ago surface-enhanced Raman (SERS) was discovered. In a nutshell, molecules positioned near roughened silver and gold surfaces were found to produce Raman spectra some 6 orders more intense than what an equivalent number of solution-phase molecules did. A large number of mechanisms were proposed to account for this spectacular effect, among which the one that seems to account for most of the observations essentially ascribes SERS to the concentration of the optical field in appropriately structured, interacting nanoscale features which operate both on the incident and Raman-scattered light. This concentration is to be appreciable only for features in which strong and narrow localized surface plasmons were excited. This “plasmonic” model not only accounted for many of SERS seminal features but also gave birth to the research fields of plasmonics and so-called metamaterials most of which achieve the necessary conditions governing the electrical permittivity and magnetic susceptibility of metamaterials in wavelength regions where plasmons are excited.
SERS was again in the news approximately 10 years ago when a number of groups pointed out that SERS from individual molecules could be observed leading some to speculate that this observation challenged the plasmonic origin of SERS. The discovery of single-molecule SERS, coincident with the intense interest of the research community in nanoscience and technology, produced a renaissance of interest in SERS that is still with us. The work of the past half dozen years reaffirmed SERS as ultimately a plasmonic effect wherein most SERS-active systems are actually rather heterogeneous with most of the enhancement originating from “hot spots” where the enhancement could top 10 orders of magnitude averaged over territory where the enhancement is rather low. The major current challenge in the field is to devise nanostructures where the hot spots dominate, leading to systems with an inordinate ability to focus electromagnetic fields so as to produce not only extraordinarily intense SERS (presumably as a super-sensitive chemical analysis tool) but also as loci where other unusual photo-induced physical and chemical processes occur when the system is illuminated with rather banal light sources. The talk will illustrate some of the most recent advances in this field.