Angle-dependent strong-field ionization of halomethanes
| Autor: | Robert Jones, Timothy T. Gorman, Péter Sándor, Timothy D. Scarborough, Adonay Sissay, Mark W. Gordon, Mette B. Gaarde, Kenneth Lopata, Kenneth J. Schafer, Francois Mauger |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Physics
010304 chemical physics Linear polarization Halomethane General Physics and Astronomy 010402 general chemistry Laser 01 natural sciences Molecular physics 0104 chemical sciences law.invention chemistry.chemical_compound Superposition principle chemistry law Ionization 0103 physical sciences Molecule Molecular orbital Density functional theory Physics::Atomic Physics Physical and Theoretical Chemistry |
| Zdroj: | The Journal of chemical physics. 151(19) |
| ISSN: | 1089-7690 |
| Popis: | We study, experimentally and theoretically, the ionization probability of singly halogenated methane molecules, CH3Cl and CH3Br, in intense linearly polarized 800 nm laser pulses as a function of the angle between the molecular axis and the laser polarization. Experimentally, the molecules are exposed to two laser pulses with a relative time delay. The first, weaker pulse induces a nuclear rotational wave packet within the molecules, which are then ionized by the second, stronger pulse. The angle-dependent ionization yields are extracted from fits of the measured delay-dependent ionization signal to a superposition of moments of the rotational wave packet’s angular distribution. Angle-dependent strong-field ionization (SFI) yields are also calculated using time-dependent density functional theory. Good agreement between measurements and theory is obtained. Interestingly, we find a marked difference between the angle-dependence of the ionization yields for these two halomethane species despite the similar structure of their highest occupied molecular orbitals. Calculations reveal that these differences are a result of multichannel (CH3Cl) vs single-channel (CH3Br) ionization and of increased hole localization on Br vs Cl. By adding calculations for CH3F, we can discern clear trends in the ionization dynamics with increasing halogen mass. These results are illustrative, as chemical functionalization and molecular alignment are likely to be important parameters for initiating and controlling charge migration dynamics via SFI. |
| Databáze: | OpenAIRE |
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