Novel infrared vibron absorption of solid hydrogen at megabar pressures

We report new phenomena associated with the infrared-active vibrons in hydrogen at megabar pressures. We find a striking 3 order of magnitude increase in vibron absorbance at the 150 GPa phase transition at 85 K. A discontinuity in the frequency of the infrared vibron is observed which is identical to that measured by Raman spectroscopy at the same temperature. The results indicate there is a significant change in electronic properties at the transition. In addition, the infrared measurements provide evidence for a phase transition at 110 GPa at low temperature.