Electronically excited states of protonated phenol and para-substituted phenol

► Compared to PhOH, the first ππ∗ transition of PhOH(H+) is slightly red shifted. ► In para-F-PhOH(H+), the red shift effect is more significant than the bare phenol. ► The first πσ∗ state of protonated phenol lies in 7A″ state and amounts to 8.29 eV.