Relationship between ionoluminescence emission and bond distance (M–O) in carbonates

Ionoluminescence emission spectra induced by 2 MeV protons are reported for a range of carbonates. A major feature in these spectra, are the Mn2+ luminescence centres that appear within all the samples. The emission wavelengths for the Mn2+ are linearly correlated to the metal–oxygen bonding length, both in rhombohedral and orthorhombic lattices for the minerals studied. The Mn2+ band, is in each case related to the corresponding energy level diagram of the mineral’s crystal lattice, as this ion perturbs the crystal field term, which for emission in rhombohedral calcite has a value of 1000 cm−1, and for orthorhombic sites in aragonite is 1200 cm−1.