X-ray powder diffraction pattern for Cu2GeSe4 crystal. Experimental data (solid red circles) are in excellent agreement with the calculated curve (solid black line). Vertical thin lines below the experimental data indicate the Bragg reflections, and the solid blue line at the base of plot is the difference between the experimental data and calculated curve.
Data (dashed color lines) and the best-fit curves (solid gray lines) for Ψ and Δ of Cu2GeSe4. The best-fit curves were obtained by a three-layer analysis of measured data.
(a) Real (red) and imaginary (blue) parts of ε spectrum for Cu2GeSe4. (b) Refractive index n (red) and extinction coefficients k (blue) spectra. (c) Normal-incident reflectivity spectrum. (d) Absorption coefficient spectrum. The spectra shown in (b)–(d) were calculated from the ε spectrum in (a).
Raman spectra of Cu2GeSe4 taken at room temperature using an excitation wavelength of 785 nm. Red circles represent experimental data and solid black trace is the best-fit curve composed of baselines (dashed gray lines) and four Gaussian-Lorentzian mixed line profiles (solid blue lines) that are labeled in numeric order. Inset: Raman spectra obtained with the excitation wavelength of 532 nm.
Observed and calculated X-ray powder diffraction data for Cu2GeSe4. The lattice parameter (a), volume (V) of unit cell, and the space group information are also given.
Atomic configuration of Cu2GeSe4 in the cubic crystal structure ( space group).
Factor group analysis for the zone-center vibrational modes of Cu2GeSe4 in the cubic crystal structure ( space group) (Γ Raman: 4 T2 and Γ IR: 4 T2).
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