Suppressi on of Ex Ci Te D-ato M T W O-p Hoton I Oni Zati on Due to Ra Bi Osci Lla Ti Ons Be Twe En Th E Exci Te D and a Lo We R State

I t is t he aim of thi s paper to extend our recent m odel [1, 2] of nom inal t wo-photon ionizati on from an isola ted exci ted state (n > 1 ) thro ugh nearthresho ld R yd berg states (n ƒ 1 ). In the model we studi ed the e ̃ects of m igratio n of popul ati on from the di rectl y excited band of hi gh-n Rydb erg states to wards com parabl e-energy Rydb erg states but of higher angular m omenta, due to a sequence of resonant V -typ e R aman coupl ings (Â l = 2 ) expl oi ti ng, as resonant interm ediaries, the orbi ta lly degenerated states of the sam e pri nci pal quantum num ber as tha t of the ini ti al sta te. It was found in [1, 2] tha t such a migratio n of popul ati on can be responsibl e for suppression of ionizati on (the strong-Ùeld ioni zati on suppression or stabi l izati on is sti l l a vi vi d problem [3]). Ho wever, one can exp ect another m echani sm of ionizati on suppression when ionizing the excited state vi a nearthresho ld R ydb erg states. In thi s paper we shal l show tha t in such a case the ini ti al -sta te to a lower-state resonance can be of great im porta nce. T o be speciÙc, let the pri ncipa l quantum numb er of the ini ti al sta te be equal to n = 7 . W hen choosing, for exam pl e, the laser frequency in such a way tha t the ini ti al sta te is in nearresonance wi th the states of the pri ncipa l quantum numb ers around n = 4 0 , then at the sam e ti m e we pro duce nearresonance wi th the lowerlying state of the pri ncipa l quantum numb er equal to 5. W hat, in fact, we are interested in thro ughout the