We investigate the beta -SiC(100) c(4x2) surface reconstruction by atom resolved scanning tunneling microscopy and Si 2p core level photoemission spectroscopy using synchrotron radiation. The STM data obtained in the filled and empty electronic states allow the identification of both the up and down dimers of the c(4x2) reconstruction The up dimers are identified when tunneling in the filled states while the down dimers are identified in the empty states. The important electronic difference between the two types of dimers is in very good agreement with core level photoemission results that show two largely shifted surface components associated with both dimers. These combined STM and photoemission experiments further confirm the AUDD model of the beta -SiC(100) c(4x2) surface.