English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Cr$^{3+}$ doped spinel compounds AB$_2$O$_4$ with A=Zn, Mg and B=Ga, Alexhibit a long near infrared persistent luminescence when excited with UV orX-rays. In addition, persistent luminescence of ZnGa$_2$O$_4$ and to a lesserextent MgGa$_2$O$_4$, can also be induced by visible light excitation via$^4$A$_2$ $ \rightarrow $ $^4$T$_2$ transition of Cr$^{3+}$, which makes thesecompounds suitable as biomarkers for in vivo optical imaging of small animals.We correlate this peculiar optical property with the presence of antisitedefects, which are present in ZnGa$_2$O$_4$ and MgGa$_2$O$_4$. By using X-rayabsorption fine structure (XAFS) spectroscopy, associated with electronparamagnetic resonance (EPR) and optical emission spectroscopy, it is shownthat an increase in antisite defects concentration results in a decrease in theCr-O bond length and the octahedral crystal field energy. A part of the defectsare in the close environment of Cr$^{3+}$ ions, as shown by the increasingstrain broadening of EPR and XAFS peaks observed upon increasing antisitedisorder. It appears that ZnAl$_2$O$_4$, which exhibits the largest crystalfield splitting of Cr$^{3+}$ and the smallest antisite disorder, does not showconsiderable persistent luminescence upon visible light excitation as comparedto ZnGa$_2$O$_4$ and MgGa$_2$O$_4$. These results highlight the importance ofCr$^{3+}$ ions with neighboring antisite defects in the mechanism of persistentluminescence exhibited by Cr$^{3+}$ doped AB$_2$O$_4$ spinel compounds.

physical chemistry chemical physics/pccp. physical chemistry chemical physics

The importance of inversion disorder in the visible light induced  persistent luminescence in Cr$^{3+}$ doped AB$_2$O$_4$ (A = Zn or Mg and B =  Ga or Al)