Excited states of aniline by photoabsorption spectroscopy in the 30 000–90 000 cm−1 region using synchrotron radiation

Abstract

The photoabsorption spectrum of aniline (C6H5NH2) in gas phase in the 30,000-90,000 cm(-1) (3.7-11.2 eV) region is recorded at resolution limit of 0.008 eV using synchrotron radiation source for the first time to comprehend the nature of the excited valence and Rydberg states. The first half of the energy interval constitutes the richly structured valence transitions from the ground to excited states up to the first ionization potential (IP) at 8.02 eV. The spectrum in the second half consists of vibrational features up to second IP (9.12 eV) and structureless broad continuum up to the third IP (10.78 eV). The electronic states are assigned mainly to the singlets belonging to π → π* transitions. A few weak initial members of Rydberg states arising from π → 4s, np or nd transitions are also identified. Observed vibrational features are assigned to transitions from the ground state A' to the excited states 1A", 3A', 5A", 6A', and 10A" in C(s) symmetry. Time dependent density functional theory (TDDFT) calculations at B3LYP level of theory are employed to obtain the vertical excitation energies and the symmetries of the excited states in equilibrium configuration. The computed values of the transition energies agree fairly well with the experimental data. Further the calculated oscillator strengths are used to substantiate the assignments of the bands. The work provides a comprehensive picture of the vacuum ultraviolet photoabsorption spectrum of aniline up to its third ionization limit.

Slow-electron velocity-map imaging study of aniline via resonance-enhanced two-photon ionization method

“…Aniline and its derivatives have been widely studied and its geometric and electronic structures are very important for understanding the property and the mechanism of electronic relaxation as a self-protection process of living organism from short wavelength radiation [1][2][3]. The radical cations of aniline and its derivatives also play an essential role in photoinduced electron transfer phenomena [4] and in the oxidation poly-condensation [5].…”

Comparing the electronic relaxation dynamics of aniline and d7-aniline following excitation at 272–238 nm

“…It has also been proposed that the two 3p Rydberg states may lie between the 1 1 pp* and 2 1 pp* states. 14,15 There have been a number of recent experimental studies of the photochemistry and photophysics of isolated aniline molecules in vacuo using H-atom (Rydberg) photofragment translational spectroscopy, 16 femtosecond pump-probe photoionisation spectroscopy, 17 femtosecond pump-probe velocity map imaging, 18 and time-resolved photoelectron imaging spectroscopy. [19][20][21][22] There have also been a number of recent theoretical investigations of the potential energy landscape and relaxation pathways following photoexcitation to the first few singlet excited states.…”

New insight into the potential energy landscape and relaxation pathways of photoexcited aniline from CASSCF and XMCQDPT2 electronic structure calculations

“…Aniline absorbs UV radiation around 282 nm (4.4 eV) and 230 nm (5.4 eV) nm. [1][2][3] These bands arise from transitions from the ground electronic state to the two lowest lying 1 pp* states.…”