Stepwise ionization of the 2,4-dioxybenzaldehyde and 3,4-dimethoxypropiophenone vapors
| Autor: | V. I. Kleimenov, M. E. Akopyan, A. G. Feofilov, M. V. Kleimenov |
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| Rok vydání: | 2002 |
| Předmět: |
Chemical ionization
Collision-induced dissociation Fragmentation (mass spectrometry) Chemistry Ionization Thermal ionization Atomic physics Photochemistry Atomic and Molecular Physics and Optics Electron ionization Ion source Electronic Optical and Magnetic Materials Atmospheric-pressure laser ionization |
| Zdroj: | Optics and Spectroscopy. 92:36-44 |
| ISSN: | 1562-6911 0030-400X |
| Popis: | The processes of stepwise ionization of the 2,4-dioxybenzaldehyde and 3,4-dimethoxypropiophenone vapors by radiation in the range of wavelengths down to 266 nm were studied using total-current spectroscopy, mass spectrometry, and photoelectron spectroscopy. The process of two-step ionization and the resulting generation of molecular ions are dominant if the laser-radiation intensity amounts to ≈106 W/cm2. These molecular ions have appreciable (up to 1.8 eV) energy of vibrational excitation. As the laser-radiation intensity increases, progressively more pronounced fragmentation occurs owing to dissociation of molecular (and, possibly, fragmentation) ions as a result of absorption of at least a single additional photon. The processes leading to fragmentation of ions are suggested. It is found that the dissociation-ionization mechanism is important for the dimethoxypropiophenone. Dissociation with a breakage of the α bond in the carbonyl group with subsequent two-photon ionization of the fragments occurs when the S 2(1 A′) state of the ππ* type is excited. |
| Databáze: | OpenAIRE |
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