The present calculation forms part of the IRON Project,
an international joint undertaking whose aims are spelt out by
Hummer et al. (1993). This, being the first paper of the
project, is henceforth referred to as IP I.
In IP IV, Saraph & Tully (1994) give thermally averaged collision strengths
for the ground term fine structure transition in fluorine like ions from
Ne II to Fe XVIII. These authors used a simple target consisting
of the two terms 
and 
. They
included in their model a non spectroscopic orbital 
which
greatly improved the theoretical term energies. In this way it was possible
to obtain reliable rate coefficients at relatively low temperatures, such
as those associated with photoionized nebular clouds for example.
Here we use an extended target representation of 28 terms. At energies between
and the 28th term the resulting collision
strengths all contain resonance structures caused by quasi-bound states that
converge onto these terms. We delineate these resonances by calculating
at several thousand energies above .
Our results for at these higher energies are combined with
those from IP IV and used to obtain thermally averaged collision strengths
which we estimate should be reliable at the higher temperatures typical of
coronal ionization equilibrium conditions.
We include the ions Co+18
and Ni+19 which were not dealt with in IP IV. For these we carried out
a 2-term calculation, as in IP IV, in order to cover the energy range between
the ground (
) and first excited (
)
terms. The observed energy of this interval is estimated to be 9.944962 Ry
for Z = 27 and 10.51617 Ry for Z = 28.
We make use of the rydberg (Ry) energy unit. For this we adopt the value
1 Ry = 109737.32 
which corresponds to a wavelength of
911.267 .
All of the IRON Project papers that have been published to date are given
in the references section. Details of these and of papers that
are in press are also available on the Internet at http://www.am.qub.ac.uk.