Scientists blast iron with lasers, and it disappears from X-rays

Scientists blast iron with lasers, and it disappears from X-rays:  Scientists took two thin sheets of the material and held it in place with carbon, which is invisible to X-rays. They placed two platinum mirrors to either side of the iron sheets. They then fired a beam of low-energy X-rays into the set-up. The beam was reflected by the platinum mirrors back and forth again and again. Trapped, it set up a standing wave in the sandwich of equipment...
When one sheet of iron was at a node, and one sheet was at an antinode (the peak or the trough), another, higher energy x-ray was shot through the entire contraption. The x-ray moved through them without interacting with either sheet of iron...