All Figures

$\begin{figure} \par\includegraphics[width=8cm,clip]{4276_f1.eps} \end{figure}$ Figure 1: The RFs considered, namely the ISRF given by Mathis et al. (1983), the RF of the extended halo surrounding the Red Rectangle proto-planetary nebula and the relatively UV-rich RF in the PDR of the planetary nebula IRAS 21282+5050; the latter two were obtained respectively from observational data (Vijh et al. 2005,2004) and from an appropriate stellar atmospheric model of Kurucz (1992).
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{4276_f2.eps} \end{figure}$ Figure 2: Comparison between the DoS of neutral coronene computed by the current model, based on Mulas (1998) (continuous line) and that of Joblin et al. (2002) (dotted line). The DoSs are perfectly coincident for energies well above the energy of a single vibrational quantum, while they differ for very low energies.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{4276_f3.eps} \end{figure}$ Figure 3: Distribution of the excitation energies at which photons are emitted by neutral bisanthene in three RFs and three vibrational bands.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f4.eps} \end{figure}$ Figure 4: Like Fig. 3 for the bisanthene cation.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f5.eps} \end{figure}$ Figure 5: Distribution of the photons emitted by neutral bisanthene in three RFs and three vibrational bands as a function of the vibrational excitation quanta in the mode.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f6.eps} \end{figure}$ Figure 6: Like Fig. 5 for the bisanthene cation.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f7.eps} \end{figure}$ Figure 7: Continuum-subtracted AIBs spectrum of the Red Rectangle, from the online ISO spectral database.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{4276_f8.eps} \end{figure}$ Figure 8: Weighted sum of the spectra of all PAHs in our sample, calculated for the Red Rectangle halo (see text for its exact definition). The dotted line shows, for comparison, the estimated dust continuum in the same source. Different panels correspond to different assumptions of rotational excitations and anharmonic widths of the bands. The axes are in logarithmic scale, wavelength in abscissa, and flux in ordinate.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{4276_f9.eps} \end{figure}$ Figure 9: ISO SWS and LWS spectrum of the Red Rectangle, showing the extrapolated dust continuum to long wavelengths (dotted line).
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{4276_f10.eps} \end{figure}$ Figure A.1: The top panel shows the comparison between the measured (dotted line; Joblin et al. 1992; Joblin 1992) and the theoretical photo-absorption cross section up to 13.6 eV (continuous line; Malloci et al. 2004) for anthracene. The cross-sections are expressed in Megabarns (1 Mb = 10^-18 cm²). The three panels below show the comparison between the resulting energy-dependent photon absorption rates for a molecule embedded in the three RFs considered.

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{4276_f11.eps} \end{figure}$ Figure A.2: Same as Fig. A.1 for pyrene (C₁₆H₁₀).

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{4276_f12.eps} \end{figure}$ Figure A.3: Same as Fig. A.1 for coronene (C₂₄H₁₂).

In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{4276_f13.eps} \end{figure}$ Figure A.4: Same as Fig. A.1 for ovalene (C₃₂H₁₄).

In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{4276_f2.eps} \end{figure}$	Figure 2: Comparison between the DoS of neutral coronene computed by the current model, based on Mulas (1998) (continuous line) and that of Joblin et al. (2002) (dotted line). The DoSs are perfectly coincident for energies well above the energy of a single vibrational quantum, while they differ for very low energies.
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$\begin{figure} \par\includegraphics[width=8.5cm,clip]{4276_f3.eps} \end{figure}$	Figure 3: Distribution of the excitation energies at which photons are emitted by neutral bisanthene in three RFs and three vibrational bands.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f4.eps} \end{figure}$	Figure 4: Like Fig. 3 for the bisanthene cation.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f5.eps} \end{figure}$	Figure 5: Distribution of the photons emitted by neutral bisanthene in three RFs and three vibrational bands as a function of the vibrational excitation quanta in the mode.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f6.eps} \end{figure}$	Figure 6: Like Fig. 5 for the bisanthene cation.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4276_f7.eps} \end{figure}$	Figure 7: Continuum-subtracted AIBs spectrum of the Red Rectangle, from the online ISO spectral database.
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$\begin{figure} \par\includegraphics[width=8.6cm,clip]{4276_f9.eps} \end{figure}$	Figure 9: ISO SWS and LWS spectrum of the Red Rectangle, showing the extrapolated dust continuum to long wavelengths (dotted line).
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