Light in the Invisible Gap
There is a region of light that has long remained a blind spot: from 5 to 15 terahertz. It is not radio waves, nor infrared heat, but something in between, where molecules vibrate in particularly characteristic ways. Scientists from Germany have built a setup that finally peers into this 'new terahertz gap' and even beyond — past 25 terahertz.
The secret lies in a crystal with the long name BNA.