Fig. 4. (Color online) Infrared spectra of the predominant LAB molecules: C11 (red circles), C12 (blue squares), and C13 (orange diamonds), highlighting peaks with transmittance below 86 for significant absorption features. Key observations include strong absorption peaks for benzene ring C-H stretching near 3000 cm-1 and alkyl chain C-H stretching between 2850–2950 cm-1. Additionally, bending modes for benzene C-H and alkyl chains are visible around 1600 cm-1 and 1500 cm-1, respectively, with lower frequency bending modes appearing between 700–800 cm-1. In particular, note that all molecules have nearly identical peak positions.
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