Excited and ionized states of aniline: Symmetry adapted cluster configuration interaction theoretical study

Abstract

Singlet excited states and ionized states of aniline are studied by the symmetry adapted cluster/ configuration interaction method. Absorption bands of states that have mainly -* nature are assigned as 1 AЉ (ϳ 1 B 2 ), 1 AЈ (ϳ 1 A 1 ), 1 AЉ (ϳ 1 B 2 ), 1 AЈ (ϳ 1 A 1 ), 1 AЉ (ϳ 1 B 2 ) in increasing-energy order. An s-Rydberg state is predicted to lie between the first and second valence states, in agreement with recent experimental results. The lowest band has a charge-resonance character with a slight charge-transfer ͑CT͒ character ͑CT is defined as NH 2 →C 6 H 5 ͒; third and fifth valence bands have back-CT ͑BCT͒ nature, and second and fourth are local excitations within the benzene ring. The extent of CT of excited states depends on amino group conformation. In the planar form, CT characters of several states were altered; however, spectral shapes are very similar to that of the equilibrium form. On the other hand, amino group twisting altered both the spectrum and nature of excited states. Third and fourth lowest valence states exhibited strong CT character, while fifth to eighth states are of the strong BCT type, implying that the CT nature of excited states of aniline can be changed by amino group twisting. For ionized states, the lowest three states are assigned to 2 AЈ (ϳ 2 B 1 ), 2 AЉ (ϳ 2 A 2 ), 2 AЈ (ϳ 2 B 1 ) in increasing-energy order, all being -ionizations. The sixth one is also due to -ionization (ϳ 2 B 1 ) and the others are -ionizations.Ordering was the same as Koopmans' case.

Substituent effects on ultrafast excited-state proton transfer of protonated aniline derivatives in aqueous solution

“…These findings clearly indicate that a proton is released from 1 ANsH þÃ into water within the lifetime of 1 ANsH þÃ . The remarkable enhancement of the proton dissociation rate of anilinium ions upon electronic excitation can be ascribed, at least partly, to a decrease of basicity of S 1 relative to S 0 of the deprotonated form due to partial delocalization of the nitrogen lone pair electrons into phenyl p system [23,24].…”

Theoretical study of valance photoelectron spectra of hypoxanthine, xanthine, and caffeine using direct symmetry‐adapted cluster/configuration interaction methodology

“…The other two p-type molecular orbitals are occupied by the lone pairs of the NH groups in the molecule. Based on the above explanations, the molecular orbitals (35,34,32,29,28,24) and (35,34,33,29,28,24) in Table 1 and Supporting Information Table S4 can be considered as the occupied p molecular orbitals. The four unoccupied p-type …”

Intensity-resolved ionization yields of aniline with femtosecond laser pulses

“…A state that lies at near resonance with the excitation energy of three photons, 4.65 eV, has recently been observed in TOF experiments using a (2 + 2) REMPI scheme [23,24] and in total kinetic energy release (TKER) spectra using 269-nm radiation [25]. This so-called new "S 2 " state has a vertical excitation energy of 4.6 eV and is close to the excitation energy of three 800-nm photons.…”