Schouder Constant, Chatterley Adam S, Calvo Florent, Christiansen Lars, Stapelfeldt Henrik
Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark.
Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark.
Struct Dyn. 2019 Aug 27;6(4):044301. doi: 10.1063/1.5118005. eCollection 2019 Jul.
Dimers of tetracene molecules are formed inside helium nanodroplets and identified through covariance analysis of the emission directions of kinetic tetracene cations stemming from femtosecond laser-induced Coulomb explosion. Next, the dimers are aligned in either one or three dimensions under field-free conditions by a nonresonant, moderately intense laser pulse. The experimental angular covariance maps of the tetracene ions are compared to calculated covariance maps for seven different dimer conformations and found to be consistent with four of these. Additional measurements of the alignment-dependent strong-field ionization yield of the dimer narrow the possible conformations down to either a slipped-parallel or parallel-slightly rotated structure. According to our quantum chemistry calculations, these are the two most stable gas-phase conformations of the dimer and one of them is favorable for singlet fission.
并四苯分子二聚体在氦纳米液滴内部形成，并通过对飞秒激光诱导库仑爆炸产生的动力学并四苯阳离子发射方向的协方差分析来识别。接下来，在无场条件下，通过非共振、中等强度的激光脉冲使二聚体在一维或三维上排列。将并四苯离子的实验角协方差图与七种不同二聚体构象的计算协方差图进行比较，发现与其中四种一致。对二聚体的取向相关强场电离产率的额外测量将可能的构象范围缩小到滑移平行或平行微旋转结构。根据我们的量子化学计算，这是二聚体在气相中最稳定的两种构象，其中一种有利于单线态裂变。
