The aqueous mixtures of UO₂²⁺(VI) (as the nitrate salt) with benzene-1,4-diol (hydroquinone, HQ) 1,4-C₆H₄(OH)₂ and those with oxalate C₂O₄²⁻ (as the sodium salt) exhibited broad absorptions at 350–400 nm in their UV–Vis spectra. The intensities of the absorptions for both the UO₂²⁺(VI)–HQ and UO₂²⁺(VI)–C₂O₄²⁻ mixtures, represented by the absorbance at 375 nm, were shown to be directly proportional to the molar concentrations of HQ and C₂O₄²⁻, respectively. For each mixture, the absorbance was also found to be directly proportional to the molar concentration of UO₂²⁺(VI). The broad absorptions are characteristic of the charge-transfer (CT) bands from the electron-donor–acceptor (EDA) complexes formed between UO₂²⁺(VI) and HQ and between UO₂²⁺(VI) and C₂O₄²⁻. Upon photolysis of the UO₂²⁺(VI)–HQ and UO₂²⁺(VI)–C₂O₄²⁻ mixtures, UO₂²⁺(VI) was found by electron paramagnetic resonance (EPR) to be reduced to UO₂⁺(V) (g = 2.08) by HQ and C₂O₄²⁻, respectively (CT reductions), and the hydroquinone radical 1,4-HOC₆H₄O^. (HQ^.) (g = 2.00) was identified simultaneously by EPR spectroscopy. Both HQ and C₂O₄²⁻ at the very low molar ratios of [HQ]/[UO₂²⁺] < 1/100 and [C₂O₄²⁻]/[UO₂²⁺] < 1/100 were shown to quench the UO₂²⁺ luminescence (emission) for more than 60%. The quenching constants of HQ and C₂O₄²⁻ were determined to be 10,800 M⁻¹ and 4,300 M⁻¹, respectively, using the Stern-Volmer relationship. The results indicated a CT quenching mechanism, namely that the interactions of HQ and C₂O₄²⁻ with the excited *UO₂²⁺(VI) lead to transfer of a single electron from the quencher to *UO₂²⁺(VI) to reduce it to UO₂⁺(V). This converts the light energy to chemical energy to quench the UO₂²⁺(VI) luminescence. Possible photochemical processes associated to the UO₂²⁺(VI)–HQ and UO₂²⁺(VI)–C₂O₄²⁻ redox reactions have been proposed on the basis of the UV–Vis, EPR, and luminescence spectroscopic studies.

UO ₂ ²⁺（VI）（作为硝酸盐）与苯-1,4-二醇（对苯二酚，HQ）1,4-C ₆ H ₄（OH）₂的水混合物和与草酸酯C ₂ O ₄的水混合物^2-（作为钠盐）在UV-Vis光谱中在350-400 nm处显示出较宽的吸收率。UO ₂ ²⁺（VI）–HQ和UO ₂ ²⁺（VI）–C ₂ O ₄ ^2-混合物的吸收强度均以375 nm的吸光度表示，与吸光度成正比。 HQ和C ₂ O ₄ ^2-的摩尔浓度， 分别。对于每种混合物，还发现吸光度与UO ₂ ²⁺（VI）的摩尔浓度成正比。宽吸收是UO ₂ ²⁺（VI）和HQ之间以及UO ₂ ²⁺（VI）和C ₂ O ₄之间形成的电子给体-受体（EDA）配合物的电荷转移（CT）带的特征²⁻。在对UO ₂ ²⁺（VI）–HQ和UO ₂ ²⁺（VI）–C ₂ O ₄ ^2-的混合物进行光解后，通过电子顺磁共振（EPR）发现UO ₂ ²⁺（VI）被还原为O₂ ⁺（V）（G = 2.08）由HQ和C ₂ Ò ₄ ^2-，分别为（CT减少），和氢醌自由基1,4-HOC ₆ H ^ ₄ ö ^。通过EPR光谱同时鉴定（HQ ^。）（g = 2.00）。既HQ和C ₂ ö ₄ ^2-在[HQ]的非常低的摩尔比/ [UO ₂ ²⁺ ] <1/100和[C ₂ Ò ₄ ^{2- ]} / [UO ₂ ²⁺ ] <1/100结果显示，UU ₂ ^2+的发光（发射）淬灭超过60％。HQ和C ₂的猝灭常数使用斯特恩-沃尔默（Stern-Volmer）关系，将O ₄ ^2-分别确定为10,800 M ^-1和4,300 M ^-1。结果表明CT猝灭机制，即HQ和C ₂ O ₄ ^2-与激发的* UO ₂ ²⁺（VI）的相互作用导致单个电子从猝灭剂转移到* UO ₂ ²⁺（VI ），将其降低到UO ₂ ⁺（V）。这将光能转换为化学能，以淬灭UO ₂ ²⁺（VI）发光。与UO ₂ ²⁺（VI）–HQ和UO ₂相关的可能的光化学过程在UV-Vis，EPR和发光光谱研究的基础上，提出了²⁺（VI）–C ₂ O ₄ ^2-氧化还原反应。