  We present a fully quantum mechanical theory to study the effects of
deformation on various reaction observables in the Coulomb breakup of neutron
rich exotic medium mass nuclei on heavy targets within the framework of finite
range distorted wave Born approximation by using a deformed Woods-Saxon
potential. As an application of this theory, we calculate the one-neutron
removal cross section, relative energy spectra, parallel momentum distributions
and angular distributions in the breakup of 31Ne on Pb and Au targets at 234
MeV/u. We suggest ways to put constraints on the large uncertainty in the
one-neutron separation energy of 31Ne and also argue that if 31Ne is indeed a
halo nucleus then it should be a deformed one.
