The probabilities of the emission of a photon by an electron and e(+)e(-)-p
air photoproduction in a field which is a superposition of two electromagne
tic plane waves with different frequencies and propagating in the same dire
ction are obtained. The case where the frequencies of the two modes are com
mensurate is studied in detail. This case is interesting primarily because
of the existence of effects due to the interference of amplitudes, correspo
nding to a different number of photons absorbed from different modes but ha
ving the same total 4-momentum. It is shown that the optimal field for obse
rving interference effects is a field such that the ratio of the mode frequ
encies is 3. The probabilities of radiation and pair-photoproduction proces
ses in the field of a monochromatic plane wave and in a two-mode field, obt
ained by splitting the initial wave into two waves, are compared. It is sho
wn that the total probability of the emission of a photon by an electron in
a two-mode field is lower than and the probability of pair photoproduction
is higher than the probabilities of the same processes in the initial wave
. The increase in the pair-photoproduction probability is explained by the
fact that additional channels for reactions which are forbidden in the init
ial monochromatic field open up in a two-mode field. (C) 2000 MAIK "Nauka/I
nterperiodica".