  One of the major challenges to identification of the 3.3, 6.2, 7.7, 8.6, and
11.3um interstellar IR emission bands with polycyclic aromatic hydrocarbon
(PAH) molecules has been the recent detection of these bands in regions with
little UV illumination, since small, neutral PAH molecules have little or no
absorption at visible wavelengths and therefore require UV photons for
excitation.
  We show here that our "astronomical" PAH model, incorporating the
experimental result that the visual absorption edge shifts to longer wavelength
upon ionization and/or as the PAH size increases, can closely reproduce the
observed infrared emission bands of vdB 133, a UV-poor reflection nebula.
  It is also shown that single-photon heating of ``astronomical'' PAHs in
reflection nebulae near stars as cool as T_eff=3000K can result in observable
emission at 6.2, 7.7, 8.6, and 11.3um. Illustrative mid-IR emission spectra are
also calculated for reflection nebulae illuminated by cool stars with
T_eff=3500, 4500, 5000K. These will allow comparison with future Space Infrared
Telescope Facility (SIRTF) observations of vdB 135 (T_eff=3600K), vdB 47
(T_eff=4500K), and vdB 101 (T_eff=5000K).
  It is also shown that the dependence of the 12um IRAS emission relative to
the total far-IR emission on the effective temperature of the exciting star is
consistent with the PAH model expectation for 3000K < T_eff < 30000K.
