Disentangling the Peak and Background Signals in Surface-Enhanced Raman Scattering

• Published in: Journal of physical chemistry. C 2012-03, Vol.116 (10), p.6184-6190
• Main Authors: Hugall, James T, Baumberg, Jeremy J, Mahajan, Sumeet
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Nanoscale materials and structures: fabrication and characterization; Other topics in nanoscale materials and structures; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp3002977

Understanding the complex relationship between peak enhancement and the underlying broad continuum (called the “background”) is crucial for developing reliable and quantitative applications of surface-enhanced Raman scattering (SERS). Here we use a gentle mechanochemical (“snow jet”) process to perturb molecules on a SERS active substrate to track the dynamics of the different contributions to SERS. By use of the snow jet process we are able to increase SERS signals on substrates by 500% or more while simultaneously increasing the peak:background intensity ratio. We identify components of the signal arising from changes in molecular distribution and surface morphology using a multiplexed time-varied exposure technique developed in-house. This allows us to distinguish between processes decaying over time and those decaying due to laser heating. Our study goes a long way toward disentangling the different contributions to SERS peak and background continuum signals and points to the different origins of these two co-occurring processes on nanostructured plasmonic substrates. This deeper understanding of the SERS process is crucial to allow SERS to reach its full potential.