Measurement of the acoustic nonlinearity parameter B/A in solvents: Dependence on chain length and sound velocity

This work consists of a systematic study of the acoustic nonlinearity param eter (BIA) in I-alkanols from methanol to l-decanol, ketones from acetone t o methyl hexyl ketone, and alkyl acetates from ethyl to octyl acetate. By f ocusing a 14-MHz tone burst through a spherical quartz lens in each solvent , the second harmonic is generated and measured by a 28-MHz transducer at v arious distances from the focus. This provides the point of maximum second harmonic power, and enables the computation of the nonlinear parameter usin g a simple model. The BIA values thus obtained are in reasonable agreement with these available in the literature. The BIA values are found to increas e with chain length and sound velocity, this increase being in contradictio n with Ballou's rule. Moreover, a hybrid model based on Schaaffs' formula f or sound velocity fits the experimental results, questioning the validity o f Ballou's rule for solvents within a single chemical family. (C) 2000 Acou stical Society of America. [S0001-4966(00)04211-9].