Mass-analyzed threshold ionization spectroscopy of 2,6-dimethylaniline, 2,6-dimethylaniline-NHD, and 2,6-dimethylaniline-ND2

We have recorded the cation spectra of three N-deuterium substituted 2,6-dimethylanilines by ionizing via the intermediate 0°, CH3 torsion, and 6a1 levels of each species in the S1 state. Comparison of the present data with those of aniline isotopomers suggests that the S1 ← S0 electronic excitation and the D0 ← S1 transition of both molecular systems are alike. By comparing these results with those of aniline and o-methylaniline, we propose an additivity rule to predict the E1 and IE. The observed active vibrations of these cations include the characteristic CH3 torsion and the in-plane ring vibrations.