The modeled dust emission per H atom for scaling factors for the the MMP83 ISRF of U = 0.1 to 10⁴. All spectra have been divided by U to emphasize the changes in the shapes of the SEDs, which are presented as I_ν to better indicate the photometric data points. The dust properties are those for DHGL model (see Sect. 4.2). The left panel shows the Spitzer (triangles) and Herschel (squares) photometric points. The right panel shows the IRAS (triangles) and Planck/HFI (squares) photometric points. To emphasize excitation effects we have assumed a constant ionization fraction for the PAHs.