  A new analysis of long-slit CGS4 (UKIRT) spectra of the 3.3 $\mu$m feature of
the Red Rectangle and its evolution with offset along the NW whisker of the
nebula is presented. The results support a proposed two-component
interpretation for the 3.3 $\mu$m feature with peak wavelengths near 3.28
$\mu$m and 3.30 $\mu$m. Both components exhibit a small shift to shorter
wavelength with increasing offset from the central star which, by comparison
with laboratory studies, is consistent with a decrease in temperature of the
carriers with distance from HD 44179. The two-component approach is also
applied to 3.3 $\mu$m data for the Red Rectangle, Orion Bar D2 and Orion Bar
H2S1 from ISO SWS studies.
