Observation of proton transfer in 2-aminopyridine dimer by electron and mass spectroscopy.
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The journal of physical chemistry. A, ISSN: 1520-5215, Vol: 113, Issue: 29, Page: 8195-201
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- Chemistry; 2-Aminopyridine; Aminopyridine; Coincidence spectroscopy; Electron ions; Electron spectrum; Electron-proton transfers; Femtosecond pumps; Hydrogen-transfer reactions; Locally excited; Mass spectroscopy; Population trapping; Reaction channels; Real time; Spectroscopic evidence; Time-resolved; Ultra-fast; Vibrational energies
A photoinitiated intermolecular electron-proton transfer reaction in 2-aminopyridine dimer was investigated by femtosecond pump-probe electron-ion coincidence spectroscopy and accompanying theory. Excited-state population dynamics were observed in real time by time-resolved mass spectroscopy, and the respective excited-state character of locally excited and proton/hydrogen transfer states was identified in coincident electron spectra. Two reaction channels for an ultrafast (sub-50 fs) and a slower (approximately 75 ps) proton/hydrogen transfer were observed and indicate that vibrational energy redistribution may lead to efficient population trapping in the excited state. Spectroscopic evidence of an unexpected hydrogen-transfer reaction in photoexcited aminopyridine monomer is also presented.