  We present ISOPHOT spectrophotometry of three positions within the isolated
high latitude cirrus cloud G 300.2 - 16.8, spanning from the near- to
far-infrared. The positions exhibit contrasting emission spectrum contributions
from the UIBs, very small grains and large classical grains, and both
semi-empirical and numerical models are presented. At all three positions, the
UIB spectrum shapes are found to be similar, and the large grain emission may
be fitted by an equilibrium temperature of ~17.5 K. The energy requirements of
both the observed emission spectrum and optical scattered light are shown to be
satisfied by the incident local ISRF. The FIR emissivity of dust in G 300.2 -
16.8 is found to be lower than in globules or dense clouds, and is even lower
than model predictions for dust in the diffuse ISM. The results suggest
physical differences in the ISM mixtures between positions within the cloud,
possibly arising from grain coagulation processes.
