Extended Data Fig. 2: X-ray photoelectron spectroscopy (XPS) spectra of the solid EBiGa sample surface.
From: Unique surface patterns emerging during solidification of liquid metal alloys

a, XPS spectrum of the Ga 2p region. b, XPS spectrum of the Bi 4f region. c, XPS spectrum of the O 1s region. The XPS analysis suggests that the dominant phases of Ga and Bi at the sample surface are Ga2O3 and metallic Bi, respectively. Such selective Ga oxidation is a result of its much greater Gibbs free energy of oxide formation (from Ga to Ga2O3, ΔGf°(Ga2O3) = -998.3 kJ mol-1) than that of Bi (from Bi to Bi2O3, ΔGf°(Bi2O3) = -493.7 kJ mol-1).