  An approach to significantly enhance spontaneous Raman sensitivity through
the formation of a thin film via thermophoresis along with evaporation at the
facet of a Hollow-Core Photonic Crystal Fiber is reported for the first time.
Sensitivity of detection is increased by more than 6 orders of magnitude for
both organic and inorganic nanoparticles, facilitating the search for trace
analytes in solution. Detection of two nanoparticles, Alumina and Polystyrene,
is demonstrated down to 392 nM without the use of Surface-Enhanced Raman
Spectroscopy or other chemical-based procedures. This new thin-film deposition
approach simplifies the simultaneous detection and analysis of small trace
compounds, a previously arduous task using conventional spontaneous Raman.
