Helium Film Formed in 1.2 nm Pore in Zeolite Templated Carbon.

Abstract  We have measured the vapor pressure of 4He adsorbed in zeolite templated carbon (ZTC) at 4.2 K, in order to examine 4He film growth in the nanopore. ZTC has a framework made of non-stacked graphene, and has a relatively uniform 1.2 nm pore with three-dimensional (3D) periodicity of 1.4 nm. The nanoporous substrate is a candidate to realize superfluid 4He film with closer 3D connectivity than those studied so far. From the vapor pressure, coverage dependences of the thickness and the two-dimensional (2D) isothermal compressibility of 4He film were derived using thermodynamic equations. The 2D compressibility indicates the onset coverage n 1 of the second adsorption layer around 20 µmol/m2. It is confirmed that the 4He film in the 1.2 nm pores grows uniformly at least up to 1.3–1.5 n 1. [ABSTRACT FROM AUTHOR]