S-polarized Angle-Dependent Reflectance (ADR) data measured from two Tantalum thin films deposited on Silicon substrates using monochromatized synchrotron radiation. The data was collected at the soft X-ray radiometry beamline (SX700) in the radiometry laboratory of the Physikalisch-Technische Bundesanstalt (PTB), in the electron storage facility BESSY II of Helmholtz Centre for Materials and Energy (HZB). The nominal thicknesses for the two thin films were 30.0 nm and 50.0 nm, hence, the .txt data files of the thin films samples are referred to as Sample-30 and Sample-50. The ADR data was collected in the Extreme Ultraviolet (EUV) range. For Sample-30 and Sample-50 the ADR was measured in the spectral ranges 5.0 nm – 24.0 nm and 10.0 nm – 20.0 nm, respectively. The EUVR of Sample-30 correspond to the angular range 3.0° – 85.5°. The EUVR of Sample-50 correspond to the angular range 4.5° – 87.0°. The .txt files contain post-processed reflectance values each with its calculated absolute uncertainty.

Acknowledgements: The data uploaded here was collected within a project which has received funding from the Electronic Component Systems for European Leadership Joint Undertaking under grant agreement No 783247 – TAPES3 (Technology Advances for Pilot line of Enhanced Semiconductors for 3 nm) and from the EMPIR Metrology for Industry project under grant No 20IND04 – Traceable metrology of soft X-ray to IR optical constants and nanofilms for advanced manufacturing (ATMOC). This Joint Undertaking receives support from the European Union's Horizon 2020 research and innovation program alongside Netherlands, Belgium, Germany, France, Austria, United Kingdom, Israel, Switzerland.