He in two-color AC-fields of λ1 = 248 nm and λ2 = (1/m) 248 nm, m = 2,3,4. The rate of multiphoton ionization, for weak fields, is a simple function of the phase

Mercouris, T; Nicolaides, CA

dc.contributor.author	Mercouris, T	en
dc.contributor.author	Nicolaides, CA	en
dc.date.accessioned	2014-03-01T01:16:37Z
dc.date.available	2014-03-01T01:16:37Z
dc.date.issued	2001	en
dc.identifier.issn	09214526	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/14118
dc.subject	Multiphoton ionization	en
dc.subject	Coherent control of ionization	en
dc.subject.other	Computational methods	en
dc.subject.other	Eigenvalues and eigenfunctions	en
dc.subject.other	Electron transitions	en
dc.subject.other	Electronic structure	en
dc.subject.other	Harmonic generation	en
dc.subject.other	Helium	en
dc.subject.other	Optical correlation	en
dc.subject.other	Photons	en
dc.subject.other	Electron correlation effects	en
dc.subject.other	Multiphoton ionization	en
dc.subject.other	Ionization of gases	en
dc.title	He in two-color AC-fields of λ1 = 248 nm and λ2 = (1/m) 248 nm, m = 2,3,4. The rate of multiphoton ionization, for weak fields, is a simple function of the phase	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0921-4526(00)00809-7	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0921-4526(00)00809-7	en
heal.publicationDate	2001	en
heal.abstract	Multiphoton ionization rates for He irradiated by a dichromatic AC-field consisting of the fundamental wavelength λ = 248 nm and its second, third and fourth higher harmonics have been computed. The calculations incorporated systematically electronic structure and electron correlation effects in the discrete and in the continuous spectrum. They were done by implementing a time-independent, nonperturbative many-electron, many-photon theory (MEMPT) which obtains cycle-averaged complex eigenvalues, whose imaginary part is the multiphoton ionization rate, Γ. It is shown that, provided the intensities are weak, the dependence of Γ on phase difference φ2, is simple. Specifically, for odd higher harmonics, Γ varies linearly with cos(φ2) whilst for even higher harmonics it varies linearly with cos(2φ2). These relations may turn out to be applicable to other atomic systems as well, and provide a definition of the weak-field regime in the dichromatic case. When the intensities are such that higher powers of cos(φ2) and cos(2φ2) become important, these rules break down and we reach the strong-field regime. © 2001 Elsevier Science B.V.	en
heal.journalName	Physica B: Condensed Matter	en
dc.identifier.doi	10.1016/S0921-4526(00)00809-7	en
dc.identifier.volume	296	en
dc.identifier.issue	1-3	en
dc.identifier.spage	271	en
dc.identifier.epage	274	en