The dust and PAH emission SED for the diffuse ISM at high Galactic latitude (solid line) calculated using our model. Also plotted here are the COBE data (symbols with error bars). These are given as an average of the data from the North ecliptic pole field and the Lockman Hole field (Arendt et al. 1998) and are further colour corrected. The contributions of the different dust compositions to the total model SED are as follows: Si (dotted line), Gra (dashed line), PAH (dashed-dotted line).