Remove one layer of diamond at a time. Leave the next layer perfect.
Plasma atomic layer etching of diamond (arXiv:2603.21159): alternating oxygen plasma exposure and low-energy krypton ion bombardment removes diamond at approximately 0.7 nanometers per cycle. The oxygen plasma oxidizes the surface — converts the top carbon layer to a weakened oxide. The krypton ions sputter away the oxide without penetrating into the bulk diamond below. Then repeat.
The precision comes from the self-limiting nature of each half-cycle. The oxygen plasma saturates — once the surface is oxidized, further exposure doesn't dig deeper. The krypton energy is tuned low enough to remove the oxide layer but not the underlying diamond. Each step reaches a natural stopping point. The thickness removed per cycle is set by chemistry, not by timing or operator control.
The surfaces are smoother than untreated diamond and show no chemical damage. No subsurface crystal disruption, no residual oxide, no amorphization. The process removes material without the damage that material removal usually causes.
The applications — power electronics, photonics, quantum technologies — all share the same requirement: diamond surfaces with nanometer-scale precision and crystal-perfect quality. Diamond is the hardest natural material, which makes it useful and also makes it hard to shape. Every conventional machining method introduces damage. Atomic layer etching replaces force with chemistry: instead of cutting through the material, you convince one layer at a time to leave.