Vapor Pressure and Heat Capacity Measurement of 3He Adsorbed on 18Å-Pores

We have measured the vapor pressure (0.84 K<T<9 K) and the heat capacity (80 mK<T<4 K) of 3He adsorbed on pores 18 Å in diameter. The results of the vapor pressure measurement indicate that 3He film grows up to the second layer. In the first layer, the heat capacity of 3He shows the same temperature and coverage dependence as 4He, indicating a solid phase. Above a little higher coverage than second layer promotion, heat capacity isotherms for 3He at several hundred mK increase with coverage while those for 4He decrease. This large heat capacity of 3He is the nuclear spin heat capacity of the second layer fluid 3He.