) eV Therefore, λ1 = 550 nm, E1 = 2.25 eV λ2 = 450 nm , E2 = 2.75 eV λ3 = 350 nm , E3 = 3.5 eV Also, ϕp = 2 eV, all λ’s cause emissions. ϕq = 2.5 eV, last two λ’s cause emissions. ϕr = 3 eV, only the last λ causes emissions. That is, Ip > Iq > Ir.