Multiphoton electron detachment from H−: a model study

Abstract

Summary. --N-photon cross-sections for the detachment of an electron from the hydrogen anion H-are evaluated by perturbation theory for 1 <~ N ~< 4 in terms of a one-electron model for the anion founded on the Fermi pseudopotential. Our results complement recent findings obtained in terms of a zero-range plane-wave approach to multiphoton detachment rates. Negative atomic ions, because of some peculiar features, are all the time attracting a lot of attention as a remarkable workbench for both experimental [1][2][3][4][5][6] and theoretical [7][8][9][10][11] multiphoton detachment (MPD) studies. This is particularly true for H- [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], whose one-electron affinity puts experimentalists in a position of detecting multiphoton absorption with light of rather small frequency [18,25], while the absence of bound intermediate states in its energy spectrum suggests to the theoreticians that the development of simple models [12,[15][16][17]20] could be a reasonably fruitful approach to the prediction of one-electron MPD behaviour. Further support to this latter remark is clearly offered also by the speculation that the ejected electron moves in a short-range potential generated by the parent neutral atom, a situation that can presumably be mimicked in some effective way.Recent data on MPD of electrons from H-anions [18,25] have been obtained by ingenious experiments where a relativistic H-beam is made to intersect a C02 laser beam at varying angles, so that the Doppler-shifted photon energy induces MPD processes associated with a variable (2 + 9) number of photons. Attempts of comparing these (fairly preliminary) data with the predictions of some theoretical models have already been reported [20][21][22][23]. By the present short paper we are being (*) The authors of this paper have agreed to not receive the proofs for correction. 463