Details
| Original language | English |
|---|---|
| Pages (from-to) | 7181-7188 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry A |
| Volume | 107 |
| Issue number | 37 |
| Early online date | 10 Jun 2003 |
| Publication status | Published - 1 Sept 2003 |
| Externally published | Yes |
Abstract
High-order harmonic generation spectra of atoms and molecules in intense laser fields show a wide plateau of odd harmonics, with photon energies high up to the soft X-ray regime. The mechanism leading to the absence of other frequencies, so-called hyper-Raman lines or sidebands, is still unclear. By the use of non-Hermitian quantum mechanics for the many-electron atomic/molecular Hamiltonian system, we derive closed-form expressions for the high-order harmonic generation spectra. The analysis of these expressions provides the (already known) conditions for which the hyper-Raman lines are missing and also the conditions for which they are observable. The new information obtained here is proof that in order to observe sidebands it is not sufficient to populate two different Floquet states. When the duration of the laser pulse is sufficiently long, the two resonance Floquet states should have similar widths (inverse lifetimes). For short pulses, the condition for observable sidebands is more complicated, and it does not depend directly on the lifetime of the resonance states. By numerical integration of the conventional time-dependent Schrödinger equation, we provide illustrative examples that confirm our conclusions. Our results can be used to design new experiments that will show the fingerprints of the hyper-Raman lines.
ASJC Scopus subject areas
- Chemistry(all)
- Physical and Theoretical Chemistry
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In: Journal of Physical Chemistry A, Vol. 107, No. 37, 01.09.2003, p. 7181-7188.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Non-Hermitian quantum mechanics for high-order harmonic generation spectra
AU - Moiseyev, Nimrod
AU - Lein, Manfred
N1 - Copyright: Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2003/9/1
Y1 - 2003/9/1
N2 - High-order harmonic generation spectra of atoms and molecules in intense laser fields show a wide plateau of odd harmonics, with photon energies high up to the soft X-ray regime. The mechanism leading to the absence of other frequencies, so-called hyper-Raman lines or sidebands, is still unclear. By the use of non-Hermitian quantum mechanics for the many-electron atomic/molecular Hamiltonian system, we derive closed-form expressions for the high-order harmonic generation spectra. The analysis of these expressions provides the (already known) conditions for which the hyper-Raman lines are missing and also the conditions for which they are observable. The new information obtained here is proof that in order to observe sidebands it is not sufficient to populate two different Floquet states. When the duration of the laser pulse is sufficiently long, the two resonance Floquet states should have similar widths (inverse lifetimes). For short pulses, the condition for observable sidebands is more complicated, and it does not depend directly on the lifetime of the resonance states. By numerical integration of the conventional time-dependent Schrödinger equation, we provide illustrative examples that confirm our conclusions. Our results can be used to design new experiments that will show the fingerprints of the hyper-Raman lines.
AB - High-order harmonic generation spectra of atoms and molecules in intense laser fields show a wide plateau of odd harmonics, with photon energies high up to the soft X-ray regime. The mechanism leading to the absence of other frequencies, so-called hyper-Raman lines or sidebands, is still unclear. By the use of non-Hermitian quantum mechanics for the many-electron atomic/molecular Hamiltonian system, we derive closed-form expressions for the high-order harmonic generation spectra. The analysis of these expressions provides the (already known) conditions for which the hyper-Raman lines are missing and also the conditions for which they are observable. The new information obtained here is proof that in order to observe sidebands it is not sufficient to populate two different Floquet states. When the duration of the laser pulse is sufficiently long, the two resonance Floquet states should have similar widths (inverse lifetimes). For short pulses, the condition for observable sidebands is more complicated, and it does not depend directly on the lifetime of the resonance states. By numerical integration of the conventional time-dependent Schrödinger equation, we provide illustrative examples that confirm our conclusions. Our results can be used to design new experiments that will show the fingerprints of the hyper-Raman lines.
UR - http://www.scopus.com/inward/record.url?scp=0141793957&partnerID=8YFLogxK
U2 - 10.1021/jp034390y
DO - 10.1021/jp034390y
M3 - Article
AN - SCOPUS:0141793957
VL - 107
SP - 7181
EP - 7188
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 37
ER -