  The ISOPHOT instrument aboard ISO has been used to observe extended FIR
emission of six Abell clusters. The raw profiles of the I_(120 um) / I_(180 um)
surface brightness ratio including zodiacal light show a bump towards Abell
1656 (Coma), dips towards Abell 262 and Abell 2670, and are without clear
structure towards Abell 400, Abell 496, and Abell 4038. After subtraction of
the zodiacal light, the bump towards Abell 1656 is still present, while the
dips towards Abell 262 and Abell 2670 are no longer noticable. This indicates a
localized excess of emitting material outside the Galaxy towards Abell 1656,
while the behavior in Abell 262 and Abell 2670 can be reconciled with galactic
cirrus structures localized on the line-of-sight to these clusters. The excess
towards Abell 1656 (Coma) is interpreted as thermal emission from intracluster
dust distributed in the hot X-ray emitting intracluster medium. The absence of
any signature for intracluster dust in five clusters and the rather low
inferred dust mass in Abell 1656 indicates that intracluster dust is likely not
responsible for the excess X-ray absorption seen in cooling flow clusters.
These observations thereby represent a further unsuccessful attempt in
detecting the presumed final stage of the cooling flow material, in accord with
quite a number of previous studies in other wavelengths regions. Finally, the
observed dimming of the high-redshift supernovae is unlikely be attributable to
extinction caused by dust in the intracluster or even a presumed intercluster
medium.
