Baffling throwaway comment about nitrogen and infrared

From sciencemag.org:

Ho-kwang Mao at the Carnegie Institution of Washington in Washington DC, tried to create this new form of nitrogen at room temperature.

Mao's team used a diamond anvil that can inflict the highest pressures ever created in a laboratory. It works like the name suggests: Two flat-topped diamonds are mechanically pressed together. Between the diamonds is a metal gasket with a small hole, where a nitrogen sample is loaded. Squeezing the diamonds together flattens the gasket and subjects the nitrogen to pressures nearly half that at the center of Earth.

Mao could watch the sample through the diamonds. At this high pressure, nitrogen lost all signs of being a molecule - infrared light that normally is absorbed by nitrogen-nitrogen bonds passed right through the sample, they report in the 7 August Physical Review Letters.

"Normally"? Didn't these clever scientist chaps get the memo that nitrogen neither absorbs nor emits infrared radiation?