Absorbing and Reflecting Powers of H2SO4 Solutions in the Far Infrared

Abstract

The reflecting and absorbing powers, and hence dispersion, of H₂SO₄ solutions were determined as a function of concentration and of wave‐length between 50μ and 150μ. Pure H₂SO₄ reflects and absorbs the far infrared less than water as is to be expected from the Debye theory on dipole orientation. A broad band around 60μ, similar to the 60μ band in water, was observed in both concentrated and dilute H₂SO₄. This band appears to be of interatomic origin and possibly a fundamental vibration frequency of the sulphate radical, SO₄, due to bending. The reflecting and absorbing powers of H₂SO₄ solutions are much greater than of pure H₂O or H₂SO₄. This is accounted for by the presence of ions which move in translation to follow the alternations of the electromagnetic waves in the far infrared. The structure of these ions is discussed in reference to other physical properties observed in H₂SO₄ solutions. It is suggested that in adding less than 5 percent water to H₂SO₄ possibly ions of SO₄^‐‐ and OH₄⁺⁺ might be formed; on further dilution, ions of H^‐ and H₃SO₅ are formed (hydrated HSO₄^‐, with the water making stable six‐ring of S–O–H–O–H–O–S); on still further dilution, ions of H⁺ and SO₄^‐‐ become most abundant.