Plasmonics: The Effect of Thermal Gradients in SERS Spectroscopy (Small 23/2010)

While the fundamental understanding of surface-enhanced Raman spectroscopy (SERS) mechanisms has been focused on electromagnetic and chemical enhancement, the effect of thermal gradients in SERS spectroscopy is neglected. The cover image addresses the importance of the photothermal effect in SERS measurements. A strong temperature gradient (∼106 K m−1) is generated by a photothermal effect on nanoplasmonic antenna upon light exposure. The photon-induced resonant excitation of surface plasmons causes electron–phonons coupling and heat dissipation in metal nanoparticles. Consequently, the temperature gradient can force analyte molecules out of confined spaces and form a circular vortex ring due to thermal diffusion and natural convection. The duality of enrichment-depletion by photothermal gradients shows significant SERS intensity changes depending on the position. The critical analysis of thermal gradient effects in SERS substrate, and the interaction of nanoplasmonic antennas and molecules will enable next-generation SERS probes with superior sensitivity. For more information, please read the Communication “The Effect of Thermal Gradients in SERS Spectroscopy” by Y. Choi, L. P. Lee, and co-workers, beginning on page 2649.