Pixel-to-pixel correlations of the integrated intensity of the 3.3 μm band (I_3.3), 3.4 μm band (I_3.4), and the 3.45 μm plateau (I_pla). The correlation coefficient R and the slope m of the linear fit to the points are also given. I_pla correlates better with the intensity of the aromatic 3.3 μm band than with the aliphatic 3.4 μm band. This indicates that the plateau is dominated by emission from aromatic bonds.