Structure factor and pair correlation function of He-4 monolayers adsorbedon evaporated gold

Temperature variations of the structure factor and the pair correlation fun ction of liquid He-4 films are derived within the chain-diagram approximati on. Using the heat capacity data of He-4 monolayers adsorbed on an evaporat ed gold substrate, we analyzed the structure factor and the pair correlatio n function as functions of the temperature and the density. The principal s tructure factor maximum and principal maximum of the pair correlation funct ion increase with decreasing density and inceasing temperature. The positio n of the principal structure factor maximum shifts smoothly toward a small value of the wave number with decreasing density, but the position of the p air correlation function increases strongly with decreasing density. Neithe r of the positions show a significant temperature dependence. The behaviors of the structure factor and the pair correlation function of He-4 films ar e generally in agreement with those of bulk liquid He-4.