JILA, Department of Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado 80309, USA.
J Chem Phys. 2012 Jan 28;136(4):044313. doi: 10.1063/1.3679170.
Negative-ion photoelectron spectroscopy of ICN(-) (X̃ (2)Σ(+)) reveals transitions to the ground electronic state (X̃ (1)Σ(+)) of ICN as well as the first five excited states ((3)Π(2), (3)Π(1), Π(0(-) ) (3), Π(0(+) ) (3), and (1)Π(1)) that make up the ICN A continuum. By starting from the equilibrium geometry of the anion, photoelectron spectroscopy characterizes the electronic structure of ICN at an elongated I-C bond length of 2.65 Å. Because of this bond elongation, the lowest three excited states of ICN ((3)Π(2), (3)Π(1), and Π(0(-) ) (3)) are resolved for the first time in the photoelectron spectrum. In addition, the spectrum has a structured peak that arises from the frequently studied conical intersection between the Π(0(+) ) (3) and (1)Π(1) states. The assignment of the spectrum is aided by MR-SO-CISD calculations of the potential energy surfaces for the anion and neutral ICN electronic states, along with calculations of the vibrational levels supported by these states. Through thermochemical cycles involving spectrally narrow transitions to the excited states of ICN, we determine the electron affinity, EA(ICN), to be 1.34(5) (+0.04∕-0.02) eV and the anion dissociation energy, D(0)(X̃ (2)Σ(+) I-CN(-)), to be 0.83 (+0.04/-0.02) eV.
ICN(-)(X̃ (2)Σ(+))的负离子光电电子能谱揭示了 ICN 基态(X̃ (1)Σ(+))以及构成 ICN A 连续体的前五个激发态((3)Π(2), (3)Π(1), Π(0(-) )(3), Π(0(+) )(3), 和 (1)Π(1))的跃迁。通过从阴离子的平衡几何形状开始，光电电子能谱在拉长的 I-C 键长为 2.65 Å 的情况下，对 ICN 的电子结构进行了表征。由于这种键的伸长，ICN 的最低三个激发态((3)Π(2), (3)Π(1)和 Π(0(-) )(3))首次在光电光谱中得到分辨。此外，光谱具有一个结构化的峰，该峰源于 Π(0(+) )(3)和 (1)Π(1)态之间经常研究的锥形交叉。通过对阴离子和中性 ICN 电子态的势能面进行 MR-SO-CISD 计算，并对这些态支持的振动能级进行计算，有助于对光谱进行归属。通过涉及到 ICN 激发态的光谱窄跃迁的热化学循环，我们确定电子亲合能 EA(ICN)为 1.34(5)(+0.04∕-0.02) eV，阴离子离解能 D(0)(X̃ (2)Σ(+) I-CN(-))为 0.83 (+0.04/-0.02) eV。
