Flow-Based Autocorrelation Studies for the Detection and Investigation of Single-Particle Surface-Enhanced Resonance Raman Spectroscopic Events

We report on the characterization and detection of single metallic nanoparticles using a combination of correlation spectroscopy and surface-enhanced resonance Raman spectroscopy (SERRS). Minimizing the number of independent characterization steps is critical to efficiently perform such an analysis. In this article, we improve upon conventional diffusion-limited approaches by implementing a flow-based system with high temporal resolution detection. The benefits of flow over diffusion measurements allow for a higher throughput of detected events resulting in shorter analysis times. The nanoparticles are sized using their rotational diffusion time calculated with a modified autocorrelation function. Experiments are performed using Au nanoparticles labeled with the reporter molecule malachite green isothiocyanate on a custom-built Raman spectrometer.