Surface-enhanced Raman spectra of melamine and other chemicals using a 1550?nm (retina-safe) laser

Many trace chemical analyses are being transitioned from the lab to the field, among which is surface-enhanced Raman spectroscopy. Although initial portable Raman analyzers primarily employ 785?nm laser excitation, recent studies suggest longer wavelengths, with an appropriate surface-enhanced Raman-active substrate, may provide equal sensitivity. Furthermore, 1550?nm excitation may provide added safety for the user, in that permanent retina damage does not occur. Here, we show that a reasonable enhancement factor can be obtained for melamine using 1550?nm laser excitation that is nearly equivalent to those obtained using 785 and 1064?nm laser excitation. We also demonstrate that a number of other chemicals of interest can be measured by 1550?nm surface-enhanced Raman scattering, albeit only modest sensitivity is achieved because of instrument limitations, not enhancement factors. Copyright (C) 2011 John Wiley & Sons, Ltd.