Structure and Dipole Moment of the First Electronically Excited State of Pyridine N‐Oxide

摘要: A study is presented of the lowest‐energy singlet—singlet transition pyridine N‐oxide in mixed crystals with p‐dichlorobenzene at 4.2°K. Polarization and Stark effect measurements on electronic orgin (at 29 599.6 cm−1) show that π*← π, 1B2← 1A1. The spectrum d5‐pyridine blue shifted by 123 cm−1 its absorption emission spectra are quite similar to those h5. vibrational analysis fluorescence spectrum, Franck—Condon patterns, suggest equilibrium geometry little affected excitation. origin band yield a value Δ μ=0.71 ± 0.03 D (assuming E ≡ 0.60 Eeff) for change dipole moment excitation; where Eeff applied effective electric fields corresponding an external field directed down a′ crystallographic axis host crystal. This small much less than predicted π‐electron theory.