plasmonic 2014 Plasmonic gas and chemical sensing_图文.docVIP

plasmonic 2014 Plasmonic gas and chemical sensing_图文 A. Tittl et?al.: Plasmonic gas and chemical sensing??177 system with?a Pd particle only 30?nm in size (Figure 11E), a factor of 2 smaller than in the experiment by Liu et?al. [93]. Still, the authors were able to detect the optical scat-tering response from single nanocones and could observe clear and reversible shifts of the plasmon scattering peak when exchanging the gaseous environment from 100 vol.% Ar to 10 vol.% H2 and back to Ar (Figure 11F). To further study the phase-transition behavior in the Pd nanoparticle, complete isotherms for hydrogenation and dehydrogenation were recorded at different temperatures. Especially, the authors chose to track the full width at half maximum (FWHM) of the plasmon peak vs. the hydrogen partial pressure instead of the more common spectral shift or peak intensity change, allowing them to observe a clear hysteresis behavior from a single 30?nm Pd parti-cle coupled to a Au nanocone antenna (Figure 11G). Using Van’t Hoff analysis, they were able to extract the enthalpy and entropy of hydride formation from the isotherm meas-urements, indicating a destabilization of the PdH phase compared to the bulk material. Furthermore, the authors extended the nanocone concept to the study of the hydro-genation kinetics of a single Mg nanoparticle. To prevent alloying and to isolate the Mg particle from neighboring materials, it was placed between two titanium layers, with a thin catalytic Pd layer placed at the top of the structure. This system configuration allowed the authors to trace a full hydrogenation isotherm for a single Mg nanodisk with a diameter of only 35 nm, demonstrating the versatility of their detection scheme. By implementing such advanced, high-throughput fabrication methods, complex plasmonic sensing geometries can be transitioned from high-resolu-tion single-particle spectroscopy towards large-scale