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Infrared spectroscopy of gas-phase polycyclic aromatic hydrocarbon cations in the 10-50 mu m spectral range
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bakker, Joost M. Redlich, Britta Meer, A. Van Der Oomens, Jos |
| Copyright Year | 2011 |
| Abstract | The gas-phase infrared spectra of four polycyclic aromatic hydrocarbon (PAH) cations have been recorded in the 10-50 {mu}m (or 1000-200 cm{sup -1}) spectral range via IR multiple photon dissociation (IRMPD) spectroscopy. Ionized PAHs are formed by UV laser ionization in an effusive beam and subsequently irradiated with a single pulse of narrowband tunable infrared light produced by the Free-Electron Laser for IntraCavity Experiments FELICE. The ion population is then analyzed in a time-of-flight mass spectrometer. Upon resonance, dissociation is induced so that IR spectra can be recorded by monitoring either the depleted parent ion intensity or the appearance of fragment ions as a function of the wavelength. The intracavity IR fluence enables the recording of IRMPD spectra of strongly bound PAH cations in the hitherto inaccessible far-IR spectral range. Experimental spectra are presented for the radical cations of anthracene, tetracene, pentacene, and coronene. Spectra calculated with density functional theory at the B3LYP/6-311g(2df,2pd) level reproduce IR frequencies reasonably accurately in this spectral range when a uniform scaling factor of 0.94 over the complete 10-50 {mu}m spectral range is employed. We show that even vibrational modes with a calculated IR intensity lower than 1 km mol{sup -1} can be observed. For themore » catacondensed PAH cations we find CH out-of-plane bending vibrations involving four adjacent CH groups within a few wavenumbers of 733 cm{sup -1}, closely matching the 13.6 {mu}m UIR band. For the larger systems, pentacene and coronene, we observe a continuous structureless background absorption above 400 cm{sup -1} which is attributed to the high density of IR dipole allowed combination modes for these systems.« less |
| Starting Page | 74 |
| Ending Page | 74 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| DOI | 10.1088/0004-637X/741/2/74 |
| Volume Number | 741 |
| Alternate Webpage(s) | https://repository.ubn.ru.nl/bitstream/handle/2066/129761/129761.pdf?sequence=1 |
| Alternate Webpage(s) | http://repository.ubn.ru.nl/bitstream/handle/2066/129761/129761.pdf?sequence=1 |
| Alternate Webpage(s) | https://doi.org/10.1088/0004-637X%2F741%2F2%2F74 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
