1. INTRODUCTION
2. SAMPLE SELECTION, OBSERVATIONS, AND DATA REDUCTION
2.1. Parent Sample
2.2. IDEOS
2.3. AKARI/IRC
2.4. Spitzer-AKARI Spectra Stitching
2.5. Star-Forming Subset: Bright-PAH Sample
3. DECOMPOSITION OF GALAXY SPECTRA FROM 2.5 − 38 µM
3.1. New Emission Components
3.2. New Absorption Features
3.3. Attenuation in Different Geometries
4. RESULTS
4.1. The Composite Template Spectra
4.2. Pahfit Result
4.3. The 3.3 µm PAH
4.4. 3.3 µm PAH as a Star Formation Rate Indicator
4.5. Low Metallicity Case Study: II Zw 40
4.6. Aromatic Versus Aliphatic
4.7. Size Diagnostics with the 3.3 µm PAH
4.8. PAH 3.3 µm Emission in Context
4.9. JWST Photometric 3.3 µm PAH Strengths
5. DISCUSSION
5.1. Impact of the Geometry: Mixed and Obscured Continuum
5.2. Impact of the Extinction Curve
5.3. The Size Distribution of PAHs
5.4. The Stability of Small Grains