He in two-color AC-fields of lambda(1)=248 nm and lambda(2) = (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	2014-03-01T01:51:09Z
dc.date.available	2014-03-01T01:51:09Z
dc.date.issued	2001	en
dc.identifier.issn	0921-4526	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/26240
dc.subject	multiphoton ionization	en
dc.subject	coherent control of ionization	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	ABOVE-THRESHOLD IONIZATION	en
dc.subject.other	INTENSE LASER FIELD	en
dc.subject.other	UNIMOLECULAR REACTIONS	en
dc.subject.other	ANGULAR-DISTRIBUTIONS	en
dc.subject.other	2-COLOR IONIZATION	en
dc.subject.other	PHOTOIONIZATION	en
dc.subject.other	INTERFERENCE	en
dc.subject.other	FREQUENCIES	en
dc.subject.other	EXCITATION	en
dc.subject.other	HYDROGEN	en
dc.title	He in two-color AC-fields of lambda(1)=248 nm and lambda(2) = (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.language	English	en
heal.publicationDate	2001	en
heal.abstract	Multiphoton ionization rates for He irradiated by a dichromatic AC-field consisting of the fundamental wavelength lambda = 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, Gamma. It is shown that, provided the intensities are weak, the dependence of Gamma on phase difference phi (2), is simple. Specifically, for odd higher harmonics, Gamma varies linearly with cos(phi (2)) whilst for even higher harmonics it varies linearly with cos(acp,). 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(phi (2)) and cos(2 phi (2)) become important, these rules break down and we reach the strong-field regime. (C) 2001 Elsevier Science B.V. All rights reserved.	en
heal.publisher	ELSEVIER SCIENCE BV	en
heal.journalName	PHYSICA B	en
dc.identifier.isi	ISI:000167877900040	en
dc.identifier.volume	296	en
dc.identifier.issue	1-3	en
dc.identifier.spage	271	en
dc.identifier.epage	274	en