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Journal articles made easy: A modern pigment

Description

This article discusses the properties of a paint pigment, manganese blue, and defines a method to map the presence of the pigment in works of art. It will help you understand the research the journal article is based on, and how to read and understand journal articles. The research article was originally published in our Chemical Communications journal. 
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Imaging, photophysical properties and DFT calculations of manganese blue (barium manganate(VI) sulphate)

– a modern pigment

 

Click here to view the full article in the journal Chemical Communications

 

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This study discusses the photo-inducedluminescence properties of manganese blue in detail, and defines a methodology to map the presence of the pigment. Mapping pigments or painting materials through imaging is crucial for two reasons:

Further information

 

 

The overall plan can be summarised as follows:

 

The electronic absorption spectrum was recorded by inserting the solid-state sample into an integrating sphere setup equipped with a spectrophotometer ranging from the UV to NIR (200-3300 nm). The scattered light was subtracted from the sample signal (the spectrum of the sample support has been previously recorded) in order to determine the light absorbed by the chromophore only.

The excitation and emission spectra were obtained with a spectrofluorimeter by fixing the emission and excitation wavelengths. A 450W Xe Lamp was used as the light source, double grating monochromators as wavelength selectors (both in excitation and emission) and a NIR sensitive photodiode as the detector. Finally, the lifetime decay was calculated by fitting the exponential curve obtained by the single photon counting technique (a pulsed laser source at 637 nm as the light source).

From these optical measurements, important parameters were calculated, such as absorption range, photoluminescence quantum yield (PLQY) and colour output. These values are essential for an accurate characterization of the pigment.  

 

    

 

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In conclusion, manganese blue - a blue pigment used in works of art from approximately 1935 to the 1990s - shows a broad light absorption (~ 500–1200 nm) and a NIR photoluminescence (1300 nm, PL = 0.5%) originating from 2E to 2T2 ligand-field (LF) transitions, according to the theoretical calculations.

 

ADDITIONAL INFORMATION

Journal articles made easy are journal articles from a range of Royal Society of Chemistry journals that have been re-written into a standard, accessible format. They contain links to the associated Chemistry World article, ChemSpider entries, related journal articles, books and Learn Chemistry resources such as videos of techniques, and resources on theory and activities. They should facilitate students understanding of scientific journal articles and how to extract and interpret the information in them.