ABSORPTION-EDGE IN LIQUID IODINE UNDER PRESSURE

Absorption coefficient measurements of the optical bands of liquid iod ine near the triple point and of the band edge along the melting curve to 1.52 GPa and 683 K are reported. The intense absorption observed i n the near ultraviolet is discussed in terms of intramolecular absorpt ion bands. The absorption edge is dominated in the 4000 to 12000 cm(-1 ) range by exponential tails of the 'Urbach' type with strongly temper ature dependent slopes and amplitudes. The possibility of connecting t he evolution of this spectral feature with the conductivity jump recen tly observed in liquid iodine around 3 GPa is discussed.