Values Γ NTO -d CD1 = 0 reflect different estimates of how the size of the hole compares to the size of the excited electron, rather than electron-hole separation per se. Sometimes (∆σ) NTO ≈ |σ elec -σ hole | even when λ 2 1 deviates significantly from unity but the overall trend is that the difference Γ NTO -d CD1 increases as λ 1 gets smaller, meaning that NTOs participate in the transition or participate to a greater degree.