For each of the compounds, the surface tension value (σ) was taken as the average of the last 20 seconds of the 10-minute period (an average of 3-5 measurements). The most surface-active of the dimer species, the aldehyde-ketone ester dimer 20, boasts a 𝑠 % * /𝑠 % value of 0.779±0.002 (a 22 percent decrease relative to aqueous ammonium sulfate). These 𝑠 % * /𝑠 % values are comparable to the 0.71±0.001 (29 percent decrease) for β-caryophyllene aldehyde, the most surface active of the β-caryophyllene oxidation products previously measured by this group. In comparing diastereomers, the largest difference in critical supersaturation ratios is 9.43±0.005 percent between the pair of diastereomeric ester dimers 16 and 21, each of which possesses two carboxylic acid groups. We note that in atmospheric SOA particles these compounds exist in complex mixtures with other dimers, higher-order oligomers, and VOCs, and not in pure one-component systems. Yet, the clear differences in CCN activation potential between pure solutions of diastereomers highlights the importance of studying the effect of backbone stereochemistry on the physical properties of atmospheric compounds.