Abstract The effect of solvated electron on photoluminescence of gadolinium(III) chloride in liquid ammonia at 293 K and a pressure of 8.8 atm is considered. The solubility of GdCl3 crystal hydrate in ammonia is 5×10−4 mol/L. The luminescence spectrum of the solvated Gd3+ ion in this solution coincides with the luminescence spectrum of the hydrated Gd3+ ion in a similar aqueous solution at atmospheric pressure. The lifetime τ in the excited state (6P7/2) of the gadolinium(III) ion is longer in ammonia (2.6 ms) than in water (2.0 ms). The luminescence of (Gd3+)* in ammonia is quenched by the solvated electron (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10733_2025_8701_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="20" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{e}}_{{\text{s}}}^{ - }\)</EquationSource>  </InlineEquation>) formed during the dissolution of metallic lithium. Under these conditions, the solution of Gd3+ and <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10733_2025_8701_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="20" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{e}}_{{\text{s}}}^{ - }\)</EquationSource>  </InlineEquation> is unstable, precipitates are formed, and the concentrations of components participating in the quenching reaction (Gd3+)* + <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10733_2025_8701_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="20" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{e}}_{{\text{s}}}^{ - }\)</EquationSource>  </InlineEquation> → Gd2+ continuously change. Because of this, the gadolinium ion photoluminescence intensity is not applicable for assessing the quenching efficiency of the solvated electron. A linear dependence of the quenching efficiency (τ0 − τ)/τ on the quencher concentration was revealed by measuring τ of the gadolinium ion at a variable concentration of es−, which was determined from the absorbance of the solution at 1400 nm in its absorption band. The bimolecular rate constant found from this relationship for the proposed quenching reaction is k = (5.3 ± 0.3) × 107 L mol−1 s−1.

Quenching of Gadolinium(III) Ion Photoluminescence by Solvated Electron in Liquid Ammonia

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2025年2月1日

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A. M. Abdrakhmanov,
G. L. Sharipov,
B. M. Gareev,
L. R. Yakshembetova

摘要

Abstract

The effect of solvated electron on photoluminescence of gadolinium(III) chloride in liquid ammonia at 293 K and a pressure of 8.8 atm is considered. The solubility of GdCl₃ crystal hydrate in ammonia is 5×10⁻⁴ mol/L. The luminescence spectrum of the solvated Gd³⁺ ion in this solution coincides with the luminescence spectrum of the hydrated Gd³⁺ ion in a similar aqueous solution at atmospheric pressure. The lifetime τ in the excited state (⁶P_7/2) of the gadolinium(III) ion is longer in ammonia (2.6 ms) than in water (2.0 ms). The luminescence of (Gd³⁺)* in ammonia is quenched by the solvated electron ( \({\text{e}}_{{\text{s}}}^{ - }\) ) formed during the dissolution of metallic lithium. Under these conditions, the solution of Gd³⁺ and \({\text{e}}_{{\text{s}}}^{ - }\) is unstable, precipitates are formed, and the concentrations of components participating in the quenching reaction (Gd³⁺)* + \({\text{e}}_{{\text{s}}}^{ - }\) → Gd²⁺ continuously change. Because of this, the gadolinium ion photoluminescence intensity is not applicable for assessing the quenching efficiency of the solvated electron. A linear dependence of the quenching efficiency (τ₀ − τ)/τ on the quencher concentration was revealed by measuring τ of the gadolinium ion at a variable concentration of e_s⁻, which was determined from the absorbance of the solution at 1400 nm in its absorption band. The bimolecular rate constant found from this relationship for the proposed quenching reaction is k = (5.3 ± 0.3) × 10⁷ L mol⁻¹ s⁻¹.