Low temperature magnetic properties of an O2 and H2O mixed molecular assembly, confined in a graphitic nanospace

The magnetic susceptibility (χ) of O2, in a slit-shaped graphitic nanospace of pore width w=0.9 nm, was measured as a function of the fractional filling (φ) by O2 and the ratio Rw of coexistent H2O to O2 in the temperature range 2 to 100 K. The effect of coexistent H2O on the χ of the bulk O2 was examined for comparison. The H2O destroyed the antiferromagnetic ordering of the α-phase of the bulk solid O2 inducing paramagnetism. O2 in the nanospace at low φ showed the paramagnetism and coexistent H2O of Rw≤0.35 accelerated the spin cluster formation. The presence of excess H2O enhanced the paramagnetism of the confined O2 due to the perfect isolation of an O2 spin by clathrate formation.