Abstract The processes leading to the appearance of phosphorescence and delayed fluorescence in organic molecular materials compete. This paper compares the ratio of the intensities of delayed fluorescence and phosphorescence with the pulse shape discrimination (PSD) capability of organic scintillators. The paper considers hot-pressed polycrystals and composite samples containing single-crystal organic grains as the heterostructured organic scintillators. The single crystals and heterostructured scintillators contained trans-stilbene, p-terphenyl, anthracene, and phenanthrene. Samples based on trans-stilbene and p-terphenyl at 77 K showed an intense delayed fluorescence, which appeared against the background of weak phosphorescence. It indicates the active formation of delayed fluorescence in these materials. We did not observe a similar effect for samples based on anthracene and phenanthrene. At the same time, it was the samples containing trans-stilbene and p-terphenyl grains that showed the best PSD capability at room temperature. Single-crystal and heterostructured materials containing the same scintillation substance demonstrate a close PSD capability. A comparative analysis of the intensities of delayed fluorescence and phosphorescence at low temperatures can be a method of searching for new materials that are promising for PSD problems.

中文翻译：

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一些异质结构有机闪烁体的延迟辐射发光

摘要 有机分子材料中导致磷光和延迟荧光出现的过程相互竞争。本文将延迟荧光和磷光的强度比与有机闪烁体的脉冲形状鉴别 (PSD) 能力进行了比较。该论文将热压多晶和含有单晶有机晶粒的复合样品视为异质结构的有机闪烁体。单晶和异质结构闪烁体包含反式二苯乙烯、对三联苯、蒽和菲。基于反式二苯乙烯和对三联苯的样品在 77 K 下显示出强烈的延迟荧光，这是在弱磷光背景下出现的。它表明这些材料中延迟荧光的形成活跃。对于基于蒽和菲的样品，我们没有观察到类似的效果。同时，含有反式二苯乙烯和对三联苯颗粒的样品在室温下表现出最佳的 PSD 能力。包含相同闪烁物质的单晶和异质结构材料表现出接近的 PSD 能力。在低温下对延迟荧光和磷光的强度进行比较分析，可以成为寻找有望解决 PSD 问题的新材料的一种方法。