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Vibronic and cation spectroscopy of structural isomers p- and m-diaminobenzene and the amino substitution effect

Paper ID Volume ID Publish Year Pages File Format Full-Text
26160 43937 2013 6 PDF Available
Title
Vibronic and cation spectroscopy of structural isomers p- and m-diaminobenzene and the amino substitution effect
Abstract

We applied the resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of p-diaminobenzene (PDAB) and m-diaminobenzene (MDAB). The band origins of the S1 ← S0 electronic transition of PDAB and MDAB were found to be 29 805 ± 2 and 33 395 ± 2 cm−1, whereas the adiabatic ionization energies were determined to be 54 624 ± 5 and 58 321 ± 5 cm−1, respectively. Most of the observed active vibrations of these two structural isomers in the electronically excited S1 and cationic ground D0 states result from in-plane ring deformation and bending vibrations. Comparing the present data with those of aniline suggests that the interaction of the amino substituent and aromatic ring in the upper (S1 or D0) state is stronger than that in the S0 state. In addition, the frequency of observed active vibrations may depend on the nature, relative location, vibrational pattern, and the extent of the amino group participated in the normal vibration.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We report the R2PI and MATI spectra of p-diaminobenzene and m-diaminobenzene. ► The first electronic transition and ionization energies are precisely measured. ► The data help us to learn the amino substitution effects on molecular properties.

Keywords
Resonant multi-photon ionization; Threshold ionization; Molecular vibration; Diaminobenzene; Cation spectrum; Vibronic spectrum
First Page Preview
Vibronic and cation spectroscopy of structural isomers p- and m-diaminobenzene and the amino substitution effect
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 251, 1 January 2013, Pages 94–99
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering