本文报导了在液氮温度范围内进行的微波受激发射的实验现象，工作物质是铬离子浓度为0.1％的人造红宝石。
An experimental observation on stimulated emission of radiation at liquid nitrogen temperature is reported. The paramagnetic material is synthetic ruby with about 0.1% chromium in Al2O3.
天然红宝石非常少见珍贵，但是人造并非太难，所以工业用红宝石都是人造的。
Ruby very rare precious natural, but not too difficult, so artificial industrial rubies are artificial.
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