Analytische Chemie
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- 2017 (2)
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The stimulated emission (SE) in aluminum laser-induced plasma pumped in resonance with the 3s23p − 3s24s aluminum transition at 266.04 nm is investigated experimentally. It is shown that the population Inversion between the 3s23p and 3s24s states can be created by weak pumping at several microjoule to millijoule pulse energies and result in high gain. The intensity of the SE at 396.15 nm is related to the number density of Al Atoms via absorption measurements. It is found that the SE in forward and backward directions with respect to the pumping laser is different in terms of the line shape and intensity that is attributed to inhomogeneity in a gain coefficient across the plasma plume.
The stimulated emission (SE) in aluminum laser-induced plasma pumped in resonance with the 3s²3p-3s²4s aluminum transition at 266.04 nm is modeled. A collisional-radiative plasma model based on kinetic equations is proposed to explain the creation of the population inversion and lasing. The model predicts fast depopulation of the ground 3s²3p state by the absorption of resonant laser light at 266 nm and very fast population of the excited 3s²4s state by the cascade transitions from the laser-pumped level, which is driven optically and by collisions. The SE of the 3s²3p-3s²4s transition at 396.15 nm is studied and possible SE at 1.3 and 2.1 μm is predicted. It is confirmed by calculations that the population inversion between the 3s²3p and 3s²4s states can be created by weak pumping at several microjoule–millijoule pulse energies and results in high gain.