1：Experimental Design and Method Selection:

The study involved preparing thin copper and gold films via electron beam evaporation and characterizing them using spectrophotometry, X-ray reflection (XRR), and scanning electron microscopy (SEM). Optical constants were determined by fitting transmission and reflection spectra using a combination of the Drude model and the beta-distributed oscillator (β_do) model.

2：Sample Selection and Data Sources:

Films with thicknesses between 10 and 60 nm were deposited on fused silica and silicon substrates. Data were sourced from spectrophotometric measurements in the 350-2000 nm range.

3：List of Experimental Equipment and Materials:

Equipment included a Bühler Syrus pro 1110 coating machine for deposition, a Perkin Elmer Lambda 950 spectrophotometer for optical measurements, a Bruker D5005 diffractometer for XRR, and a Carl Zeiss Sigma SEM for surface morphology. Materials included Au 5N+ from SAXONIA and Cu 5N from Umicore, with substrates of fused silica Q1 and silicon wafers.

4：Experimental Procedures and Operational Workflow:

Films were deposited at a rate of 0.5 nm/s with quartz crystal monitoring. Spectrophotometry was performed at near normal incidence, and spectra were fitted using MATLAB. XRR and SEM were used for non-optical characterization to determine thickness, density, and surface roughness.

5：5 nm/s with quartz crystal monitoring. Spectrophotometry was performed at near normal incidence, and spectra were fitted using MATLAB. XRR and SEM were used for non-optical characterization to determine thickness, density, and surface roughness. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using spectra fits with the Drude and β_do models, with parameters extracted through iterative fitting. Thickness was also estimated using XRR and a sum-rule-based approach.