(Color online) The behavior of the sizes of the nanoshell under pressure. The top panel presents the radii of the core and shell as a function of pressure. Notice that the golden shell will be compressed more than the core until about GPa where the core/shell ratio reaches a maximum. The bottom panel shows this ratio , which is an important parameter for the optical response. The radii of the nanoshells in this article correspond to the size of commercially available nanoshells.
(Color online) The pressure-dependent permittivity of different materials. The permittivity of was calculated from the Vinet EOS and the Clausius-Mossotti relation. The other permittivites are based on the literature.27
(Color online) The relative cross section as a function of wavelength for different pressures for a nanoshell with parameters as mentioned in the figure. Notice the pressure-induced blueshift of the dipole peak from at GPa to at GPa as indicated by the two vertical lines.
(Color online) The position of the dipole resonance peak as a function of the pressure for a nanoshell with parameters as mentioned on the figure. The two horizontal black lines correspond to the two vertical lines on Fig. 3. The blueshift from at GPa to at GPa as predicted by Mie theory is clearly visible. The open circles were calculated with hybridization theory and also indicate a blueshift, but predict a different peak position. The inset shows the peak shift as a function of pressure compared to the original position at zero pressure.
(Color online) The position of the dipole peak as calculated with Mie theory for various pressure media: helium27 (circles), hydrogen28 (diamonds), and neon27 (triangles). In all figures, the vacuum position is indicated in black for reference and the phase transition from liquid to solid is indicated. The plots only show the pressures for which experimental data is available. For completeness, the original data are presented in Table II together with the pressure range in which they are valid.
(Color online) The dipole peak position as a function of pressure for the coated nanoshell with a core, a -thick golden shell, and for different thicknesses of the outer coating. For small coatings, the redshift caused by the medium is still clearly visible, whereas for thick coatings this effect seems to disappear. The crosses indicate the pressure at which the wavelength peak position is maximal and where the redshift turns into a blueshift.
(Color online) Schematic overview of the modeled system: region will be the core, region the golden shell, region the coating, and region the pressure medium.
The material properties used in the pressure calculations of the nanoshell. Parameters and are valid up to GPa for gold and GPa for amorphous silicon according to, respectively, Refs. 24 and 22. The last column indicates the relative permittivity at ambient pressure. The permittivity indicated for gold is the bulk permittivity as defined in Eq. (1).
The refractive index of materials used as pressure medium in a DAC as reported by Refs. 27 and 28. The last column presents the pressure range of the data on which these fits are based. The dielectric function can be calculated by squaring the refractive index.
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