Molecular orbital model of optical centers in bismuth-doped glasses

Abstract

Spectroscopic properties of optical fibers with a bismuth-doped silicate glass core are explained on the basis of molecular orbital theory and a solution of the Schrödinger equation, which takes into account the exchange, the spin-orbital, and the glass field potential interactions of s, p, and d electron shells of bismuth with s(sigma), p(sigma), and p(pi) orbits of oxygen atoms. The approach can explain the IR luminescence properties of other optical centers formed by other atoms with the same structure of electron shells as the bismuth atom. The model of transitions based on intramolecular charge transfer between molecular orbital and metallic states is proposed.

Discussion on the origin of NIR emission from Bi-doped materials

“…Kustov et al [45,46] developed an ICT model for BiO 4 to explain the spectroscopic properties of Bi-doped glasses. The model is based on the molecular orbital theory and a solution of the Schrödinger equations.…”

“…Surprisingly, the nature of this NIR photoluminescence is still unknown, although many hypotheses have been formulated, attributing emission to Bi 5+ [37][38][39][40], Bi-clusters [17], Bi + [22,23,25,26,28,34,35], BiO [8,31,41], dimer ions Bi 2 , Bi 2 − and Bi 2 2− [11,12,24,42], Bi 0 [43,44], molecular orbital models [40,45,46] or even point defects [21]. In the present paper, all these attempts to clarify the origin of NIR emission will be critically evaluated with the goal to condense the accumulated information into a potential resolution of the problem, and to identify directions for future research.…”

Effect of Si doping on near-infrared emission and energy transfer of Bismuth in silicate glasses

“…Despite the fact that several proposals have been made tentatively, assigning the role of emission center to Bi 5+ , Bi + , Bi metal clusters or negatively charged Bismuth dimmers, the origin of NIR emission still remains highly debated [1,3,[17][18][19][20][21][22]. According to Duffy's theory of optical basicity, the increasing basicity of the host glass will facilitate formation of higher valence states of Bi [23,24].…”

Ultrabroad emission from a bismuth doped chalcogenide glass

“…We examined various published energy level models of Bi doped glasses to see if our emission bands at 2000 and 2600 could be accounted for. These models included a molecular orbital model of a BiO 4 molecule [44] and a model based on quantum-chemical calculations of Bi 2 − and Bi 2 2…”