As the phenol concentration increases to 0.450 M, Q/s reveals a predominant contribution of the tetramer, even if the monomer remains as major component. In contrast, C/d shows a more balanced contribution across the different aggregates. Finally, in the most concentrated sample, the tetramer band is the most intense with Q/s, while C/d provides again a more evenly distributed contribution among the aggregates, with an increased contribution of the tetramer compared to lower concentrations. The spectra in Figure display a complex band structure with numerous well-resolved peaks in the 3150-3600 cm -1 region. This effect, observed with both the Q/s and especially the C/d strategies, contrasts with the broad, structureless band seen in experimental data .