This work reports a theoretical analysis of the Li͑2s → 2p͒ photoabsorption spectra when the lithium atoms are evolving in a ground helium buffer gas. The influence of temperature on the far-line wing spectra is particularly examined by adopting classical and full quantum-mechanical approaches. The computations show the appearance, above approximately 1000 K, of satellite structures in the blue wing around the wavelength 536 nm. The data obtained in the range of temperature 500-3000 K agree very well with those already calculated with different theoretical methods.

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This work proposes a theoretical study of the Li(2p ← 2s) photoabsorption spectra perturbed by ground hydrogen atoms. The temperature effect on the far-wing spectra is examined in the temperature range 4000-20 000 K. For this purpose, the ground and excited LiH potential curves and the transition dipole moments that connect them are constructed from ab initio data. The investigation shows that the profile spectra are dominated at all temperatures by the singlet A ← X transitions and exhibit in the red wing a satellite structure near the wavelength 1000 nm. The spectra revealed also the appearance beyond 14 000 K of a second satellite structure in the blue wing close to the wavelength 510 nm originating from the triplet c ← a transitions.