1：Experimental Design and Method Selection

Laser ablation of solids in liquids was applied to improve the UV absorption properties of a HAp based Fe-containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared respectively).

2：Sample Selection and Data Sources

The FeHAp powder was prepared by treating cod fish bones with a basic FeCl2 solution and successively calcining them at 700 oC. The composition of the material was HAp, a mixed phosphate of calcium and iron Ca9FeH(PO4)7 and α-Fe2O3.

3：List of Experimental Equipment and Materials

Diode-pumped Nd:YVO4 source for green laser, similar laser source for infrared laser, JEOL JSM-6700 field emission Scanning Electron Microscopy (SEM), JEOL-JEM 2010 FEG transmission electron microscope, Inductively Coupled Plasma-Optical Emission Spectrometre (ICP-OES) – Perkin Elmer Optima 4300 DV, θ/θ diffractometer (PANalytical X'Pert Pro, NL), Malvern Nano-ZS90 instrument for DLS measurements, Micromeritics Gemini 2380 surface area analyser, Perkin Elmer Lambda 1050 for UV-Vis spectra.

4：Experimental Procedures and Operational Workflow

The powder was first milled in a planetary ball mill for 20 minutes, and then sifted through a stainless-steel sieve (75 μm openings). The resulting material was used to prepare suspensions at two different concentrations in distilled water – 2.5 and 10 g/l – which were employed for the laser treatments.

5：Data Analysis Methods

The morphology and microstructure of the samples was studied with SEM and TEM. Elemental composition was determined using ICP-OES. The phase composition was assessed through XRD. UV-Vis spectra were taken with a Perkin Elmer Lambda 1050.