Abstract
We have developed new techniques for measuring infrared spectra at megabar pressures using synchrotron radiation and applied them to study the (1), (1)+(0), and (J) vibrational transitions of solid hydrogen to 180 GPa. The frequency difference between the (1) infrared and Raman vibrons increases from 3 (zero pressure) to 510 (180 GPa), including a dramatic increase in intermolecular coupling with pressure. A negative frequency shift is observed for the infrared vibron above 140 GPa. A significant increase in frequency and LO-TO splitting of the lattice phonon is also documented.
- Received 6 January 1992
DOI:https://doi.org/10.1103/PhysRevLett.69.1129
©1992 American Physical Society