Relaxation of electronic excitations in K2GeF6 studied by means of time-resolved luminescence spectroscopy under VUV and pulsed electron beam excitation

•Crystalline K2GeF6 particles were synthesized by co-precipitation.•Fast cross- and intraband luminescence with decay times 300–500 ps was observed.•Transitions between valence sub-bands (Ge 4s,4p, F 2p) cause intraband luminescence.•The decay of K 3p cation excitons results in the formation of Ge 4s,4p holes.•Electronic band structure parameters of K2GeF6 were experimentally determined.