X pert mrd

Different concentrations of poly(methyl methacrylate) (PMMA) molecules, a commonly used positive electron-beam resist, are used as model analyte in our experiment. For the largest concentration, a thin layer of PMMA (950-A2, 2% solid content in anisole, Michrochem) is spin-coated on top of the metamaterials at 2000 rpm. PMMA is chosen in the present work due to the accurate control of the uniform thickness obtainable via control of the spin speed and molecule concentration used. Then molecule concentration is diluted progressively in anisole and the diluted polymer solution is spun onto nanostructures. The dielectric function of the polymer can be modeled as ε_dilute = f·ε_PMMA + (1−f)·ε_anisole in numerical simulations, where ε_PMMA and ε_anisole are permittivity of readily obtained PMMA (950-A2) and anisole and f is the filling ratio of the PMMA. The thicknesses of diluted polymers with different concentrations are determined through X-ray reflectivity (Philips X'Pert-MRD) measurement and the respective thicknesses of different concentrations are shown in Fig. S1(a).

X-ray diffraction experiments were performed at room temperature to study the crystalline structure of the materials using an X-ray diffraction system (Philips X Pert-MRD, the Netherlands) employing CuKα radiation (X-ray wavelength λ = 1.5406 Å) under normal laboratory conditions. The chemical compositions and crystallographic structures of samples were recorded by varying the angle following Bragg’s law, which is satisfied by the d-spacing in polycrystalline materials.

The crystal structures
of the prepared
films were analyzed using X-ray diffraction (XRD; X’Pert-MRD,
Philips, and SmartLab, Rigaku, λ = 0.154 nm). The ω-2θ scans were carried out to estimate the lattice
parameters by performing 2θ scans while changing the incident
angle (ω). The 2θ position of Si (lattice parameter: 5.43)
was used as a reference (Coll. Code: 51,688). The film thickness was
estimated using wavelength-dispersive X-ray fluorescence (WD-XRF;
Axios PW4400/40, PANalytical), and the results were compared to those
of a reference sample. The crystal structures of the films under an
applied electric field were investigated using a microfocus X-ray
diffraction (XRD) setup with a 2D detector (Bruker AXS D8 DISCOVER)
by focusing X-rays on the Pt-top electrodes. X-rays were focused onto
a Pt-top electrode with ϕ = 200 μm, to which an electric
field of 250 kV/cm amplitude was applied, and diffraction patterns
were collected by a two-dimensional detector. A collimator with a
pinhole with a 100 μm diameter was used.