We review the phase diagram of nitrogen in a wide pressure and temperature range. Recent optical and x-ray diffraction studies at pressures up to 300 GPa and temperatures in excess of 1000 K have provided a wealth of information on the transformation of molecular nitrogen to a nonmolecular (polymeric) semiconducting and two new molecular phases. These newly found phases have very large stability (metastability) range. Moreover, two new molecular phases have considerably different orientational order from the previously known phases. In the iota phase (unlike most of other known molecular phases), N{sub 2} molecules are orientationally equivalent. The nitrogen molecules in the theta phase might be associated into larger aggregates, which is in line with theoretical predictions on polyatomic nitrogen.

Interview with LeRoy Ellis Cox. The interview includes Cox's personal experiences about childhood and early adulthood in Texas, New Mexico, Arizona, and Colorado, World War-II-era Army Air Corps training in armaments and electronics, stateside service in the 303rd Bomb Group of the Eighth Air Force, aviation cadet training, serving as a B-25 instructor pilot, and as a DC-3 tow pilot for the glider program.