Multiphoton detachment rates of H- for weak and strong fields

Haritos, C; Mercouris, T; Nicolaides, CA

dc.contributor.author	Haritos, C	en
dc.contributor.author	Mercouris, T	en
dc.contributor.author	Nicolaides, CA	en
dc.date.accessioned	2014-03-01T01:16:46Z
dc.date.available	2014-03-01T01:16:46Z
dc.date.issued	2001	en
dc.identifier.issn	1050-2947	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14213
dc.subject.classification	Optics	en
dc.subject.classification	Physics, Atomic, Molecular & Chemical	en
dc.subject.other	Algorithms	en
dc.subject.other	Atomic physics	en
dc.subject.other	Carbon dioxide	en
dc.subject.other	Eigenvalues and eigenfunctions	en
dc.subject.other	Electron energy levels	en
dc.subject.other	Light polarization	en
dc.subject.other	Perturbation techniques	en
dc.subject.other	Photons	en
dc.subject.other	Doubly excited states (DES)	en
dc.subject.other	Multiphoton electron detachment rates (MPEDR)	en
dc.subject.other	Hydrogen	en
dc.title	Multiphoton detachment rates of H- for weak and strong fields	en
heal.type	journalArticle	en
heal.identifier.primary	10.1103/PhysRevA.63.013410	en
heal.identifier.secondary	013410	en
heal.identifier.secondary	http://dx.doi.org/10.1103/PhysRevA.63.013410	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	The time-independent Schrödinger problem for the H- plus ac field system has been solved from first principles via the nonperturbative many-electron, many-photon theory (MEMPT) for a wide range of values of frequency ω and of intensity I of linearly polarized light. The calculations obtained the multiphoton electron detachment rates (MPEDRs) as the imaginary part of a complex eigenvalue and were done for combinations of values of ω and of I defining regimes of ""weak"" and of ""strong"" fields. Most of the results cover the cases of two-, three-,..., seven-photon electron detachment, studied as a function of frequency and of intensity. However, special cases, such as the one of I=2 × 1011 W/cm2 for the CO2 frequency of 0.117 eV, represent detachment processes into various symmetries requiring the absorption of at least 25 photons. The MEMPT results were obtained without any empirical adjustment of energies or of basis sets. The dressed-atom resonance wave function consisted of optimized function spaces for the initial and final states, including the lowest1S,1P0, and1D doubly excited states (DES). The initial state was represented by a ten-term numerical multiconfigurational Hartree-Fock wave function whose energy, -0.5275 a.u., is very close to the exact one, - 0.5277 a.u., and which accounts self-consistently for electron correlation as well as for the proper magnitude of the 1s orbital at large values of r. The H- DES wave functions were correlated, yielding accurate energies. However, their presence does not affect the results at all. The results converged well when 15 photon blocks were used. In spite of the large number of absorbed photons required in cases such as the CO2 frequency, the calculations converged well, within the numerical accuracy of the algorithms, by using free-electron angular momenta with 1 up to 7. The systematic quantitative study of the dependence of the MPEDRs on ω and I has led to conclusions as to the behavior at thresholds and as to the limits of validity of the predictions of the lowest-order perturbation theory. An interesting result is the appearance of intensity-dependent structures in the two-, four-, and six-photon detachment rates, which is caused by the interference of the1S and1D channels. For a number of (I, ω) pairs, comparison is possible with published results obtained by earlier large-scale calculations which either started from first principles or used parametrized one-electron models. Overall, there is good agreement. We conclude that the current level of theoretical knowledge of the H-MPEDR spectrum is very satisfactory for a large set of experimentally possible laser parameters. ©2000 The American Physical Society.	en
heal.publisher	American Inst of Physics, Woodbury, NY, United States	en
heal.journalName	Physical Review A - Atomic, Molecular, and Optical Physics	en
dc.identifier.doi	10.1103/PhysRevA.63.013410	en
dc.identifier.isi	ISI:000166383000084	en
dc.identifier.volume	63	en
dc.identifier.issue	1	en
dc.identifier.spage	1	en
dc.identifier.epage	15	en