Quantum effects on the temperature dependence of surface tension of simple liquids

An equation of general applicability is proposed to describe the surface tension of simple liquids over an extended temperature range. This equation incorporates the quantum effects on the exponent μ, which characterizes the temperature dependence of surface tension. Far from the critical region, μ decreases with increasing de Boer parameter and appears to reach a constant value μapprox. =1 for 4He and 3He. It is pointed out that for quantum liquids μ crosses over to the nonquantum mechanical value of μapprox. =1.28 as the critical point is approached. The surface tension and its temperature dependence are predicted for hydrogen isotopes such as T2, DT, D2, HT, and HD