Electronic spectroscopy of 1-(phenylethynyl)naphthalene
Philipp Constantinidis1, Melanie Lang, Jörg Herterich
1Institute of Physical and Theoretical Chemistry, University of Würzburg , Am Hubland, D-97074 Würzburg, Germany.
The Journal of Physical Chemistry. A
|April 2, 2014
Summary
1-(phenylethynyl)naphthalene (1-PEN) is confirmed as a key polycyclic hydrocarbon in combustion. Spectroscopic studies validate its identity and provide insights into its electronic and vibrational properties.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Combustion Science
Background:
- 1-(phenylethynyl)naphthalene (1-PEN) is proposed as a significant product from phenylpropargyl radical dimerization in combustion.
- Understanding the properties of 1-PEN is crucial for modeling hydrocarbon combustion processes.
Purpose of the Study:
- To spectroscopically investigate and confirm the identity of 1-(phenylethynyl)naphthalene (1-PEN).
- To characterize the electronic and vibrational properties of 1-PEN, including its excited states and ionization energy.
Main Methods:
- Infrared (IR) spectroscopy was used to confirm the molecular structure.
- Multiphoton ionization (MPI) spectroscopy determined the electronic transition origin and vibrational modes.
- Threshold photoelectron spectroscopy (TPES) measured the ionization energy and cation electronic states.
Main Results:
- IR spectroscopy confirmed 1-PEN as the dimerization product of phenylpropargyl radicals.
- MPI revealed the S1 electronic origin at 30823 cm⁻¹, with torsional progressions observed.
- TPES yielded an ionization energy of 7.58 eV for 1-PEN, with an excited cation state at 7.76 eV.
Conclusions:
- The spectroscopic data unequivocally confirm 1-PEN's identity and its role in combustion chemistry.
- Detailed characterization of 1-PEN's electronic and vibrational structure provides valuable data for combustion modeling.
- The study offers insights into the excited state dynamics and ionization properties of this important polycyclic hydrocarbon.
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