4-Chloro-3-fluoroaniline studied by resonant two-photon ionization and mass-analyzed threshold ionization spectroscopy

The excitation energy of the S1 ← S0 transition (E1) and the adiabatic ionization energy (IE) of 4-chloro-3-fluoroaniline (4C3FA) are found to be 33 242 and 63 868 cm−1, respectively. Comparing these data with those of 4-chloroaniline, 3-fluoroaniline, and aniline, we find an additivity rule associated with the E1 and IE. This implies that the interaction among the Cl, F, and NH2 substituents is weak. The new vibronic and cation spectra 4C3FA can be used as fingerprints for molecular identification.