Pentacene in 1,3,5-Tri(1-naphtyl)benzene: A Novel Standard for Transient EPR Spectroscopy at Room Temperature
Pentacene in 1,3,5-Tri(1-naphtyl)benzene: A Novel Standard for Transient EPR Spectroscopy at Room Temperature
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DOI：
10.1007/s00723-021-01420-4
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发表时间：
2021-09
影响因子：
1
通讯作者：
M. Schröder;D. Rauber;Clemens Matt;C. W. Kay
中科院分区：
文献类型：
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作者：
M. Schröder;D. Rauber;Clemens Matt;C. W. Kay
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。在瞬变电子顺磁共振(EPR)谱中，并五苯并对三联苯的单晶被广泛用于这一目的。然而，这种样品也不是没有缺点：晶体需要生长，EPR转变只出现在晶体相对于外部磁场的特定取向上。并五苯的另一种宿主是玻璃形成的1，3，5-三(1-萘基)苯(TNB)。由于TNB具有较高的玻璃化转变点，在室温下得到了含有无规取向并五苯分子的非晶态玻璃。在这里，我们证明了在脉冲激光激发下，五苯并五苯溶解在TNB中，产生了典型的粉末状的三重态的EPR谱。从二维数据集中，通过光谱模拟可以直接得到零场分裂参数和相对布居数，以及微波谐振腔内的场。由于制备、操作和稳定性的简单性，该系统是调整相对于微波谐振器的激光束和向学生介绍瞬时EPR光谱的理想选择。
Testing and calibrating an experimental setup with standard samples is an essential aspect of scientific research. Single crystals of pentacene inp-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 thefield 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.