Characterisation of the muonium states in carbazole and its isomer 1H-Benzo[f]indole

Commercial carbazole (Cz) has been widely used as a building block in organic materials for optoelectronic applications, acting as a light-absorbing, electron donor and emitting moiety，which has led to recent breakthroughs in ultralong organic phosphorescence, thermally activated delayed fluorescence, organic luminescent radicals and organic semiconductor lasers. Molecular crystals from pure Cz and its derivatives display ultralong organic phosphorescence (UOP) at room temperature. However, different groups have reported inconsistent quantum efficiencies for the same compounds. The mechanisms behind UOP are yet to be fully understood. Here, we want to characterise the muonium states in Cz and its isomer 1H-Benzo[f]indole to gather sufficient background information to be able to successfully perform a photomusr experiment in the future.