A strongly spin-dependent lifetime is reported for the n = 1 image-pot
ential surface state at Fe(110). Spin-resolved inverse photoemission m
easurements reveal an intrinsic linewidth of 140 +/- 10 meV for the mi
nority image state, about twice as large as the 70 +/- 10 meV observed
for the majority state. The spin dependence of the lifetime can be ex
plained in terms of the spin-dependent density of bulk electronic stat
es in iron, on the assumption that escape into bulk states accompanied
by electron-hole-pair production is the main decay channel. The bindi
ng energies are magnetically split by 57 +/- 5 meV. This result suppor
ts the predicted predominant influence of the spin-polarized substrate
potential on the binding energy, modified by a small effect of the sp
in-polarized surface barrier.