We report the discovery of a new class of molecular phases of solid nitrogen at high pressures and temperatures by Raman and infrared spectroscopy and powder x-ray diffraction. Unlike the molecular phases consisting of disk- and sphere-like molecular disorder (δ-, ϵ- and ζ-N2) and reportedly stable over a wide P-T range, one of the new phases (ι) is diatomic with disk-like molecules. A second new phase (the higher pressure θ-phase) is characterized by strong intermolecular interactions and infrared vibron absorption. Both phases exhibit wide P-T ranges of stability and metastability.
@article{arxiv.cond-mat/0111482,
title = {New Phases of Solid Nitrogen},
author = {Eugene Gregoryanz and Alexander Goncharov and Russell J. Hemley and Ho-kwang Mao and Maddury Somayazulu and Guoyin Shen},
journal= {arXiv preprint arXiv:cond-mat/0111482},
year = {2007}
}