The calculated collision strengths (
) for fine-structure transitions
involving the 
ground state and the 
metastable state
are averaged over a Maxwellian velocity distribution to
obtain effective collision strengths (
)
as a function of electron temperature in the range 
.
This procedure is detailed in Paper I.
The results are shown in Tables 4 (click here) and 5 (click here).
Table 4: Effective collision strengths 
for electron excitation
up to the first 10 J levels of Fe I, initial levels 1,2 & 3.
We use the notation 
to indicate the number 
Table 5: Effective collision strengths 
for electron excitation
up to the first 10 J levels of Fe I, initial levels 4 to 9.
We use the notation 
to indicate the number 
An example plot of one particular collision strength
is shown in Fig. 1 (click here).
Some resonance features can be seen due to excitation into states of 
.
Figure 1: Log - log plot of collision strength 
, solid
line, with fits showing the forms of the Wigner threshold
behaviour, dotted & dashed lines
The figure also demonstrates that the collision strength exhibits
Wigner threshold behaviour (Wigner 1948)
of the form 
where l is the dominant angular momentum contribution,
i.e. l=0 for s-wave, l=1 for p-wave etc.
At the lowest energies the s-wave dominates but as the energy approaches
the next thresholds the p-wave contribution becomes evident.
The approximate fits are 
for the s-wave
(0.0 to 0.004 Ryd) and 
for the p-wave
(0.004 to 0.07 Ryd). All 45 transitions exhibit similar behaviour
although clearly for different values of l and energy.