Possible centers of broadband near-IR luminescence in bismuth-doped solids: $B{i}^{+}$, Bi${}_5^{3+}$, and Bi${}_4^0$

Subvalent bismuth centers (interstitial $B{i}^{+}$ ion, Bi${}_5^{3+}$ cluster ion, and Bi${}_4^0$ cluster) are examined as possible centers of broadband near-IR luminescence in bismuth-doped solids on the grounds of quantum-chemical modeling and experimental data.