An analyze of vitreous As₂S₃ network structure models and photoinduced change of the structure is done in this paper. Is concluded that the interpretations of the results are not equivocal. Application of mass spectrometry, although it is an indirect method, contribute to the identification of main particles created during the evaporation of As ₂S₃ glass in vacuum. As was established, the As ₄S₃, As₄S₄, As₄S ₅, As₂S₃, As₂S₄, As ₂S₅, As₂S₆ molecular units and the As₃S₄ ·, As₃S₃ ·, As₃S₂ ·, As₃S·, As·, AsS₂ ·, As₂S·, As₃S₂ ·, As₂S₂ ·, S₂ ·, As·, As₂ ·, As₃ · free radicals exist in the gas phase. The clusters like As₁₀S₁₅ can be created during the deposition on the substrate. Clusters are characterized by a different spatial structure with the same ratio of As/S atoms of 2:3. This particularity can explain the deposition of thin As₂S₃ films with different optical properties.