Binding Energy of He Dimer in Nanotubes: Effect of Adsorption Potential

Dimer formation by He atoms confined in a narrow tube is studied and the effect of adsorption potential is clarified. The results are well explained in terms of the effective radius and the width of the single-particle ground-state wave function Δρ. For 3 He, adsorption potential promotes dimer formation when \(\langle \rho\rangle \lesssim 3\) A, but is unfavorable when \(\langle \rho \rangle \gtrsim 3\) A. We discuss the recent experimental results for 3 He atoms confined in nanopores in light of the present results.