About: http://webisa.webdatacommons.org/231842594

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Impurities such as oxygen, nitrogen, etc., were below the detectable level by X-ray excited photoelectron spectrometry.
http://www.w3.org/ns/prov#wasQuotedFrom	google.es