Production Mechanisms and Radiative Lifetimes of Argon and Xenon Molecules Emitting in the Ultraviolet

The time dependences of uv emissions from dense argon and xenon are monitored following low-intensity electron excitation. The uv transitions originate on the lowest $0_{\mathrm{u}}^{+}$ and $1_{\mathrm{u}}$ molecular states. For argon the radiative lifetimes are 3.2±0.3 μsec ($1_{\mathrm{u}}$) and 4.20±0.13 nsec ($0_{\mathrm{u}}^{+}$), while for xenon they are 96±5 and 5.5±1.0 nsec. The radiating molecules are formed by three-body destruction of excited atoms; the rate coefficient for argon is (2.8±0.3) × ${10}^{-33\mathrm{}}$ ${\mathrm{cm}}^6$/sec.