In Situ Au L3 and L2 edge XANES spectral analysis during growth of thiol protected gold nanoparticles for the study on particle size dependent electronic properties

► A u L edge XAS of thiol protected gold nanoparticles (AuNPs) were analyzed. ► The origin of the characteristic absorption band of the AuNPs was investigated. ► The band is due to Au--S scatterings and electronic transfer from Au to S. ► The electronic properties of the AuNPs with various sizes were evaluated. ► The electrons are increasingly transferred to S atoms as the size.