One of the major criticisms of identifying the infrared emission bands with
polycyclic aromatic hydrocarbon (PAH) molecules has been the lack of a mat
ch between laboratory spectra of individual PAHs and the emission features.
Part of the difficulty arises from the complexity of modeling the emission
mechanism with an a priori unknown mixture of ionized and neutral PAHs. A
direct comparison between laboratory spectra of PAHs and astronomical sourc
es is possible for absorption spectra. However, because of poor atmospheric
transmission, ground-based spectra of the PAH absorption band in the C-H s
tretch region are too noisy to make a detailed comparison with laboratory s
pectra. In this paper we show that ISO Short Wavelength Spectrometer spectr
a of a few protostars that show a 3.25 mum absorption band can be well matc
hed by laboratory absorption spectra of a mixture of isolated PAHs.