Testing and calibrating an experimental setup with standard samples is an essential aspect of scientific research. Single crystals of pentacene in p-terphenyl are widely used for this purpose in transient electron paramagnetic resonance (EPR) spectroscopy. However, this sample is not without downsides: the crystals need to be grown and the EPR transitions only appear at particular orientations of the crystal with respect to the external magnetic field. An alternative host for pentacene is the glass-forming 1,3,5-tri(1-naphtyl)benzene (TNB). Due to the high glass transition point of TNB, an amorphous glass containing randomly oriented pentacene molecules is obtained at room temperature. Here we demonstrate that pentacene dissolved in TNB gives a typical “powder-like” transient EPR spectrum of the triplet state following pulsed laser excitation. From the two-dimensional data set, it is straightforward to obtain the zero-field splitting parameters and relative populations by spectral simulation as well as the \(B_{1}\) field in the microwave resonator. Due to the simplicity of preparation, handling and stability, this system is ideal for adjusting the laser beam with respect to the microwave resonator and for introducing students to transient EPR spectroscopy.

使用标准样品测试和校准实验装置是科学研究的一个重要方面。p中的并五苯单晶-三联苯在瞬态电子顺磁共振 (EPR) 光谱中广泛用于此目的。然而，该样品并非没有缺点：需要生长晶体，并且 EPR 跃迁仅出现在晶体相对于外部磁场的特定方向上。并五苯的替代主体是玻璃化的 1,3,5-三（1-萘基）苯 (TNB)。由于TNB的玻璃化转变点高，常温下可得到含有随机取向并五苯分子的无定形玻璃。在这里，我们证明溶解在 TNB 中的并五苯在脉冲激光激发后给出了典型的“粉末状”瞬态 EPR 谱。从二维数据集中，\(B_{1}\)微波谐振器中的场。由于制备、操作和稳定性的简单性，该系统非常适合调整与微波谐振器相关的激光束，并向学生介绍瞬态 EPR 光谱。