Franck–Condon Factors in Electronic Excitations from the Ground and Excited Vibrational States Are Different

Vibrational fine structure observed in the published He–I UV photoelectron spectra of H2 and N2 molecules recorded at room temperature under microwave excitation or 700 °C have been reexamined compared with calculations Franck–Condon factors (FCFs) using simple harmonic oscillator wave functions and/or those obtained Morse potentials. In general, FCFs are used to explain vibronic transitions UV–vis diatomic polyatomic molecules, which can be computed differing levels complexity. We advocate constructing vibrational numerically, rather than analytically, help a program such as Excel, Origin, Python. this way students also verify normalization orthogonality numerical integration routes provided within these programs. Special attention is drawn possible deviations vibrationally excited from ground states.