  The $t$-channel exchange of two gluons in a color singlet state represents
the lowest order approximation to the Pomeron. This exchange mechanism is
thought to also explain the formation of rapidity gaps in dijet events at the
Tevatron. At the perturbative level this requires suppressed gluon emission in
the rapidity interval between widely separated jets, analogous to color
coherence effects in $t$-channel photon exchange. By calculating the imaginary
part of the two gluon, color singlet exchange amplitude we show how this
pattern does emerge for gluon emission at small transverse momenta. At large
$p_T$ the radiation pattern characteristic for color octet single gluon
exchange is reproduced.
