EFFECT OF SALTS AND DISSOLVED-GAS ON OPTICAL CAVITATION NEAR HYDROPHOBIC AND HYDROPHILIC SURFACES

The effect of four 1:1 electrolytes (KCI, KBr, NH4Cl, and CH3COONa) on optical (stimulated by laser pulse) cavitation in thin layers bounded by hydrophobic and hydrophilic surfaces has been explored, For water and all salts (up to 1 M) in the case of hydrophobic surfaces, the cav itation probability is enhanced as compared with the case of hydrophil ic walls. The increased cavitation probability observed with hydrophob ic surfaces can be linked to an enhanced concentration of gas-filled s ubmicrocavities close to them. The phenomenon seems to depend strongly on dissolved gas. Variations in the probability of cavitation that oc cur with electrolyte are significant and depend on its concentration a nd type. The specific effect of electrolytes on optical cavitation in a thin layer likely makes sense only in terms of the previously neglec ted ionic dispersion interactions. The results obtained may have impli cations for the mechanisms of the long-range hydrophobic interactions between surfaces and hydrophobic slippage.