Experimental and Theoretical Studies of Photoluminescence from Bi82+ and Bi53+ stabilized by [AlCl4]- in Molecular Crystals

TL;DR

This study combines experimental and theoretical approaches to understand the photoluminescence of Bi82+ and Bi53+ polycations stabilized by [AlCl4]- in molecular crystals, revealing their emission characteristics and electronic transitions.

Contribution

It provides a systematic investigation of the structural and luminescent properties of bismuth polycations, with quantum chemistry calculations clarifying their photophysical behaviors.

Findings

Bi82+ emits near 1180 nm in the near-infrared.

Bi53+ produces longer-wavelength emission.

Quantum calculations link excitation bands to specific electronic transitions.

Abstract

The photophysical properties of Bi82+ and Bi53+ polycations stabilized by [AlCl4]- have been studied experimentally and theoretically. The obtained product was thoroughly evaluated by powder X-ray diffraction and photoluminescence spectroscopy, making it clear that both Bi82+ and Bi53+ contribute to the observed broad near-infrared emission. Furthermore, it was revealed that Bi82+ polycation mainly results in the emission peaking at ca. 1180 nm, while Bi53+ the longer-wavelength emission. The following quantum chemistry calculation on Bi82+ polycation helps us attribute some observed excitation bands in the visible spectral range to specific electronic transitions of bismuth polycations. It is believed that systematical investigation of structural and luminescent properties as well as detailed quantum chemistry calculation of molecular crystals containing such kinds of bismuth units allows us to obtain a clearer picture on bismuth-related photophysical behaviors, which not only serve to solve the confusions on the luminescence origin of bismuth in other material systems such as bulk glasses, glass fibers and conventional crystals, but also is helpful to develop novel applicable broadband tunable laser mediums.