Humboldt-Universität zu Berlin - SALSA School of Analytical Sciences Adlershof

Making use of luminescence emission in Raman experiments

In 2015 the Journal of Raman spectroscopy published the article "Shedding light onto the spectra of lime", written by Dr. Thomas Schmid and Dr. Petra Dariz, which presents reliable spectroscopic data of the phases of the lime cycle: CaO (burnt lime), Ca(OH)2 (slaked lime), and CaCO3 (limestone, lime mortar). The paper presents Raman spectra and a previously not described narrowband red luminescence emission assigned to Raman-inactive calcium oxide. As this effect was hitherto misinterpreted as Raman scattering in some cases, the paper explains how to distinguish Raman and luminescence bands, which can appear in the same spectra. With > 50 citations, this paper is now listed within the ten most cited articles published in the Journal of Raman spectroscopy 2015-2016.

luminescence

Schematic explanation of narrowband red luminescence emission by MgO:Cr3+, detectable in most MgO and CaO samples by using Raman equipment
(Table-of-contents figure of J. Raman spectrosc. 52 (2021) 1462-1472).

 

The story is not over yet: In 2021, Thomas and Petra published "Shedding light onto the spectra of lime–Part 2", explaining the reason for the narrowband red luminescence observed in CaO and MgO samples obtained by calcination of Ca and Mg carbonates, whose Raman spectra are included in the study as well. If you are interested in the typically underestimated role of transistion (or d-block) elements in inorganic luminescence phenomena – often only associated with rare earth (or f-block) elements –, or if you never have really understood ligand field theory, this is our recommended read. Furthermore, in that paper Thomas and Petra demonstrate how to make use of this luminescence phenomenon for imaging the micrometre-scale distributions of Raman-active and Raman-inactive phases within complex materials, such as 19th-century cement mortars.

 

Publications:

Part-1 paper: T. Schmid, P. Dariz, J. Raman Spectrosc. 46 (2015) 141-146.

 
 

 

Part-2 paper: T. Schmid, R. Kraft, P. Dariz, J. Raman Spectrosc. 52 (2021) 1462-1472.