Surface-enhanced resonance Raman scattering in optical tweezers using co-axial second harmonic generation

Silica particles were partially coated with silver, and a suitable chromophore, such that they could be trapped within an optical tweezers system and simultaneously be excited to emit a surface–enhanced resonance Raman scattering (SERRS) spectrum. A standard 1064 nm TEM00 mode laser was used to trap the bead whilst a frequency doubling crystal inserted into the beam gave several microwatts of 532 nm co-linear light to excite the SERRS emission. The configuration has clear applications in providing apparatus that can manipulate a particle whilst simultaneously obtaining surface sensitive sensory information.