Fig. 2

a Panorama of The Music (9.51 m length × 8.84 m wide) artwork, b Section of The Music artwork showing the measurement points as M1 to M5, and the reference zone were the UV–Vis spectra were taken

a Panorama of The Music (9.51 m length × 8.84 m wide) artwork, b Section of The Music artwork showing the measurement points as M1 to M5, and the reference zone were the UV–Vis spectra were taken