Optimized pulses for Raman excitation through the continuum: Verification using the multiconfigurational time-dependent Hartree-Fock method
| Autor: | Daniel J. Haxton, K. Birgitta Whaley, C. William McCurdy, Loren Greenman |
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| Rok vydání: | 2017 |
| Předmět: |
Physics
Quantum Physics education.field_of_study Valence (chemistry) 010304 chemical physics Atomic Physics (physics.atom-ph) Population Hartree–Fock method FOS: Physical sciences Pulse sequence Configuration interaction 01 natural sciences Physics - Atomic Physics Atomic orbital Ionization 0103 physical sciences Atomic physics Quantum Physics (quant-ph) 010306 general physics education Excitation |
| Zdroj: | Physical Review A. 96 |
| ISSN: | 2469-9934 2469-9926 |
| DOI: | 10.1103/physreva.96.013411 |
| Popis: | Author(s): Greenman, L; Whaley, KB; Haxton, DJ; McCurdy, CW | Abstract: We have verified a mechanism for Raman excitation of atoms through continuum levels previously obtained by quantum optimal control using the multiconfigurational time-dependent Hartree-Fock (MCTDHF) method. For the optimal control, which requires running multiple propagations to determine the optimal pulse sequence, we used the computationally inexpensive time-dependent configuration interaction singles (TDCIS) method. TDCIS captures all of the necessary correlation of the desired processes but assumes that ionization pathways reached via double excitations are not present. MCTDHF includes these pathways and all multiparticle correlations in a set of time-dependent orbitals. The mechanism that was determined to be optimal in the Raman excitation of the Ne 1s22s22p53p1 valence state via the metastable 1s22s12p63p1 resonance state involves a sequential resonance-valence excitation. First, a long pump pulse excites the core-hole state, and then a shorter Stokes pulse transfers the population to the valence state. This process represents the first step in a multidimensional x-ray spectroscopy scheme that will provide a local probe of valence electronic correlations. Although at the optimal pulse intensities at the TDCIS level of theory the MCTDHF method predicts multiple ionization or excitation ionization of the atom, at slightly lower intensities (reduced by a factor of about 4) the TDCIS mechanism is shown to hold qualitatively. Quantitatively, the MCTDHF populations are reduced from the TDCIS calculations by a factor of 4. |
| Databáze: | OpenAIRE |
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