Photoelectron current modulation in multiphoton detachment of H-

Recently, we have carried out calculations of cross sections of photodetach ment of a negative ion irradiated simultaneously by a weak photodetaching e lectromagnetic field of frequency omega(H1) and an intense low-frequency bi chromatic field (LF) when the frequencies omega(L1) and omega(L2) Of its co mponents are commensurate. It has been found that, when omega(L2) = 2 omega (L1) and the relative phase of the LF fields is pi/2, the photoelectron spe ctra show a very pronounced maximum when the ejected electron absorbs by th e LF field an amount of energy almost equal to the ponderomotive shift prov ided by the bichromatic field. In this communication an explanation of the location of the maximum of the photoelectron current is given, and the anal ysis is extended to the case in which different ratios of omega(L2)/omega(L 1) are considered. Further, the possibility of quantum control of the photo electron current by the addition of an extra low-intensity detaching field of such a frequency omega(H2) that omega(H2) - omega(H1) is equal to an int eger multiple of omega(L1) is reported on. It is found that, by changing th e relative phase phi of the two photodetaching weak fields, the photoelectr on current can be strongly modulated by the action of the bichromatic field and that such a modulation depends in a very simple way on phi.