Investigation of the Kramers–Kronig analysis: revised optical constants of AgCl

White and Straley have reported room-temperature optical constants, α, κ, and ∊2 for AgCl that exhibit negative, unphysical dips at the band edge. Because Morrison also obtained such behavior for InAs, InSb, and GaAs, we have studied possible sources of this anomaly. An artifact of the experimental reflectance data near this energy is found to be responsible. No defect in the Kramers–Kronig transform or its use is implied, contrary to some suggestions. The corrected optical constants of AgCl were modified by ~10% up to 5 eV, whereas at higher energies they were barely affected. Thus Kramers-Kronig-deduced optical constants that exhibit unusual structure are not affected by this structure at other energies. The new AgCl results are presented, and assignments are briefly discussed.