The ordering of IEs in diphosphene is not clearly established and no information has been reported in the literature concerning the arsenic analogues. We have investigated the electronic properties of two diarsenes using UV Photoelectron Spectroscopy and by calculation (DFT). Comparison between the phosphorus and arsenic spectra has also been made. From this work it has been determined that n+ and π orbitals are closed shell and their energy separation depends on the substituent (more separated considering aryl substituent).