Abstract
Our molecular dynamics investigation is the first one which describes the two-dimensional supercritical behavior of the ethanol monolayer spread at the air/water interface. Two-dimensional cluster analysis for the aggregation of adsorbed ethanol molecule in the monolayer shows that the state of monolayer transits from the non-percolating state to the percolating state across the percolation threshold, which is a typical behavior of supercritical fluid. The occurrence of a percolation transition is confirmed in terms of the universal quantities, the value of which only depends on the dimensionality of the system. The first example of the universal quantity is the critical space-occupation probability density ; the calculated value is about 0.5, which agrees with its universal value 0.44 in 2D system. Another example is the critical exponent for the non-percolating cluster number distribution ; the calculated value is 1.96, which agrees with its universal value 2.05 in 2D system. The cluster structure is also investigated.
