Theory and computation of the rate of multiphoton two-electron ionization via the direct mechanism

Mercouris, T; Haritos, C; Nicolaides, CA

dc.contributor.author	Mercouris, T	en
dc.contributor.author	Haritos, C	en
dc.contributor.author	Nicolaides, CA	en
dc.date.accessioned	2014-03-01T01:17:16Z
dc.date.available	2014-03-01T01:17:16Z
dc.date.issued	2001	en
dc.identifier.issn	0953-4075	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14425
dc.subject.classification	Optics	en
dc.subject.classification	Physics, Atomic, Molecular & Chemical	en
dc.subject.other	Approximation theory	en
dc.subject.other	Electron absorption	en
dc.subject.other	Electron emission	en
dc.subject.other	Electron resonance	en
dc.subject.other	Electronic structure	en
dc.subject.other	Hamiltonians	en
dc.subject.other	Helium	en
dc.subject.other	Photons	en
dc.subject.other	Polarization	en
dc.subject.other	Wave equations	en
dc.subject.other	Single-ionization channels	en
dc.subject.other	Wavefunctions	en
dc.subject.other	Impact ionization	en
dc.title	Theory and computation of the rate of multiphoton two-electron ionization via the direct mechanism	en
heal.type	journalArticle	en
heal.identifier.primary	10.1088/0953-4075/34/19/305	en
heal.identifier.secondary	http://dx.doi.org/10.1088/0953-4075/34/19/305	en
heal.language	English	en
heal.publicationDate	2001	en
heal.abstract	This paper discusses aspects of the physics and the computation of rates of multiphoton two-electron ionization of polyelectronic atoms within a nonperturbative, time-independent framework. A fundamental characteristic of the theory is that the physically significant features of the spectrum, of electronic structure and of free-electron channels enter systematically in an N-electron field-dressed resonance trial wavefunction. This many-electron, many-photon theory produces the rate of a particular field-induced process as the imaginary part of a frequency- and intensity-dependent complex eigenvalue obtained from the solution of a suitably constructed non-Hermitian Hamiltonian matrix. The notion of direct two-electron ionization is expressed in terms of a specific form of the trial wavefunction, which consists of configurations with real and complex square-integrable functions, subject to orthogonality constraints so as to exclude the participation of single-ionization channels, assumed to contribute mainly to the sequential path. The applications were done to the two-electron ejection from He by the direct absorption of two linearly polarized photons (photon energy in the range 35.0-55.0 eV) and to H- from. the direct and the sequential absorption of four, three, two and one photons (photon energy in the range 4.08-15.00 eV). The comparison between the rates of the two paths in H-, for photon energies 7.18-10.5 eV, shows that the direct rate dominates. We also show that in the orbital Hartree-Fock approximation to the initial state, the frequency-dependent rates at the intensity of 1 x 10(13) W cm(-2) differ from those obtained with a correlated wavefunction by about two orders of magnitude.	en
heal.publisher	IOP PUBLISHING LTD	en
heal.journalName	Journal of Physics B: Atomic, Molecular and Optical Physics	en
dc.identifier.doi	10.1088/0953-4075/34/19/305	en
dc.identifier.isi	ISI:000172118300009	en
dc.identifier.volume	34	en
dc.identifier.issue	19	en
dc.identifier.spage	3789	en
dc.identifier.epage	3811	en