Indirect nanoplasmonic sensing: ultrasensitive experimental platform for nanomaterials science and optical nanocalorimetry.

Indirect nanoplasmonic sensing is a novel experimental platform for measurements of thermodynamics and kinetics in/on nanomaterials and thin films. It features simple experimental setup, high sensitivity, small sample amounts, high temporal resolution (<10(-3) s), operating conditions from UHV to high pressure, wide temperature range, and applicability to any nano- or thin film material. The method utilizes two-dimensional arrangements of nanoplasmonic Au sensor-nanoparticles coated with a thin dielectric spacer layer onto which the sample material is deposited. The measured signal is spectral shifts of the Au-sensor localized plasmons, induced by processes in/on the sample material. Here, the method is applied to three systems exhibiting nanosize effects, (i) the glass transition of confined polymers, (ii) catalytic light-off on Pd nanocatalysts, and (iii) thermodynamics and kinetics of hydrogen uptake/release in Pd nanoparticles <5 nm. In (i) and (iii), dielectric changes in the sample are detected, while (ii) demonstrates a novel optical nanocalorimetry method.