  The infrared (IR) emission from interstellar dust in the Small Magellanic
Cloud (SMC) is modelled using a mixture of amorphous silicate and carbonaceous
grains, including a population of polycyclic aromatic hydrocarbon (PAH)
molecules. (1) It is shown that this dust model is able to reproduce the
spectral energy distribution from near-IR to far-IR for the entire SMC Bar
region, provided the PAH abundance in the SMC Bar region is very low. (2) The
IR spectrum of the SMCB1#1 molecular cloud can also be reproduced by our dust
model provided the PAH abundance is increased relative to the overall SMC Bar.
The PAHs in SMCB1#1 incorporate ~3% of the SMC C abundance, compared to <0.4%
in the SMC Bar. (3) The spectrum of SMCB1#1 is best reproduced if the PAH
mixture has intrinsic IR band strengths which differ from the band strengths
which best fit Milky Way PAH mixtures. The variation in the PAH IR band
strengths would imply different PAH mixtures, presumably a consequence of
differing metallicity or environmental conditions. Other possibilities such as
super-hydrogenation of PAHs and softening of the starlight spectrum are also
discussed.
