Figure S5b. Calibration of Sn-K edge energies vs. oxidation state									
Standard	Oxidation state	Photon energy							
Na4Sn	-4	29195.9							
Sn	0	29200.1							
SnO	2	29202.2							
SnO2	4	29206.2							
Microcrystalline	3.7	29205.5							
