Luminescence spectroscopy of Cr3+ and Mn2+ in spodumene (LiAlSi2O6)

Luminescence emission and excitation spectra of a number of natural spodumene crystals have been measured at temperatures down to 12 K. Both Cr3+ and Mn2+ centres were identified; Mn2+ is shown to be mainly in Li-sites rather than Al-sites and gives rise to a broad emission centred at 600 nm. In most spodumenes Cr3+ R-line emission with phonon sideband is observed at temperatures below 100 K. In the more Mn-rich crystals multiple R1 lines are seen at temperatures below about 40 K, but in Cr-rich crystals only one r1 line is observed and Cr3+ emission is evident at room temperature.