Ar₂ excimer emission from a laser-heated plasma in a high-pressure argon gas

We investigated a pump scheme to establish a practical Ar₂ excimer laser operating at 128 nm. In this scheme, electrons generated by preionization of Ar gas at high pressure were heated by intense pulsed CO₂ laser radiation. The resultant high-density plasma in the high-pressure Ar gas was used to create excited Ar dimers, In the experiment, a CO₂ laser beam from a transversely excited atmospheric CO₂ laser was focused on a narrow line, 100 mm in length, in Ar gas at a pressure of 2 MPa. A vacuum ultraviolet (VUV) signal was observed only when the Ar was preionized, and the VUV signals were identified as the emission of Ar₂ excimers from the features of the spectrum which was centered on 128 nm.