应该是vibronic coupling,也就是振动能级偶合到电子跃迁中,如果是这样的话,改变溶剂的极性会改变峰的相对强度,因为the major contributions to vibronic band intensities is from specific solute-solvent dipole-dipole coupling, although other effects due to π-orbital interactions between solute and solvent and bulk dielectric constant of solvent cannot be neglected.