Ultrafast vibrational spectroscopy in the mid-infrared spectral range provides the opportunity to probe the dynamics of electronic states involved in all stages of the singlet fission reaction through their unique vibrational frequencies. This capability is demonstrated using a model singlet fission chromophore, 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn). The alkyne groups of the TIPS side chains are coupled to the conjugated framework of the pentacene cores, enabling direct examination of the dynamics of triplet excitons that have successfully separated from correlated triplet pair states in crystalline films of TIPS-Pn. Relaxation processes during the separation of triplet excitons and triplet–triplet annihilation after their separation result in the formation of hot ground state molecules that also exhibit unique vibrational frequencies. Because all organic molecules possess native vibrational modes, ultrafast vibrational spectroscopy offers a new approach to examine the dynamics of electronic intermediates that may inform ongoing efforts to utilize singlet fission to overcome thermalization losses in photovoltaic applications.

中文翻译：

---

利用分子振动探测单峰裂变过程中的三重态动力学

中红外光谱范围内的超快振动光谱学提供了机会，通过其独特的振动频率来探测单线态裂变反应的所有阶段所涉及的电子态的动力学。使用模型单重态裂变生色团6,13-​​双（三异丙基甲硅烷基乙炔基）并五苯（TIPS-Pn）证明了这种能力。TIPS侧链的炔基与并五苯核的共轭骨架偶联，可直接检查三重态激子的动力学，该动力学已成功地从TIPS-Pn晶体膜中的相关三重态对状态中分离出来。三重态激子和三重态-三重态an灭分离过程中的弛豫过程会导致形成热基态分子，这些分子也表现出独特的振动频率。由于所有有机分子都具有固有的振动模式，因此超快振动光谱学提供了一种检查电子中间体动力学的新方法，该方法可为正在进行的利用单重态裂变克服光伏应用中的热损失所做出的努力提供信息。