Time-Resolved Optical Emission Spectroscopy Diagnosis of CO₂ Laser-Produced SnO₂ Plasma

The spectral emission and plasma parameters of SnO₂ plasmas have been investigated. A planar ceramic SnO₂ target was irradiated by a CO₂ laser with a full width at half maximum of 80 ns. The temporal behavior of the specific emission lines from the SnO₂ plasma was characterized. The intensities of Sn I and Sn II lines first increased, and then decreased with the delay time. The results also showed a faster decay of Sn I atoms than that of Sn II ionic species. The temporal evolutions of the SnO₂ plasma parameters (electron temperature and density) were deduced. The measured temperature and density of SnO₂ plasma are 4.38 eV to 0.5 eV and 11.38×10¹⁷ cm ⁻³ to 1.1×10¹⁷ cm ⁻³, for delay times between 0.1 µs and 2.2 µs. We also investigated the effect of the laser pulse energy on SnO ₂ plasma.