Quantitative extinction and transient resonant four-wave mixing

The data refer to two optical imaging methods. 1. Wide-field imaging optical extinction method to rapidly and quantitatively measure the optical extinction cross-section (also polarisation resolved) of a large number of individual gold nanoparticles, for statistically-relevant single particle analysis. Using this method, we have characterized nominally-spherical gold nanoparticles in the 10-100nm size range. The data are the measured extinction cross-sections (as images and .dat ascii files) for these particles. Data of the optical extinction cross-section for in-house fabricated nanoparticle conjugates are also available, demonstrating distinction of individual dimers from single particles and larger aggregates. 2. Transient resonant four-wave mixing micro-spectroscopy. This is a nonlinear optical microscopy method which detects single gold nanoparticles through light-matter interaction at the localised surface plasmon resonance. Owing to an interferometric and time-resolved detection, this technique is very specific to metallic nanoparticles and background-free. Rather than providing the absolute value of the optical extinction cross-section, the technique is sensitive to the change in the nanoparticle extinction induced by a short pump pulse. In turn, owing to the phase-sensitivity of the interferometric detection, we can measure the pump-induced ultrafast change in the particle polarisability as a complex quantity, i.e. separating its real and imaginary parts. The data shown are the measurements of these quantities, and theoretical models to them, for single gold nanoparticles and dimers.

Results derived from these data are published at http://dx.doi.org/10.1039/C5FD00079C