[davep]

I am researching infrared fluorescent materials and I have come across 2 compounds which (from my basic knowledge of chemistry) should be identical but according to the literature have different absorption and emission spectra.  Can anyone shed some light on this (excuse the pun)?

The first is Barium Manganate (VI) Sulphate (xBaSO4.yBaMnO4) [1] which has a broad band emission at ~1300nm.

The second is BaSO4:Mn6+ [2] which has a broad band emission at ~1050nm.

What is the difference between these compounds and how does it affect the absorption / emission spectra?

Thanks in advance.

[1] - Imaging, photophysical properties and DFT calculations of manganese blue (barium manganate(VI) sulphate) – a modern pigment
[2] - Spectroscopic Investigation on BaSO4:(Mn6+, Mn5+) Crystal