Resolving the F 2 bond energy discrepancy using coincidence ion pair production (cipp) spectroscopy
Resolving the F 2 bond energy discrepancy using coincidence ion pair production (cipp) spectroscopy
复制标题
使用重合离子对产生 (cipp) 光谱解决 F 2 键能差异
DOI：
10.1039/d1cp00140j
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发表时间：
2021
影响因子：
3.3
通讯作者：
Sztáray, Bálint
中科院分区：
文献类型：
--
作者：
Matthíasson, Kristján;Kvaran, Ágúst;Garcia, Gustavo A.;Weidner, Peter;Sztáray, Bálint
在DELICIOUS III型符合谱仪上记录了F2在125 975 ~ 126 210 cm−1单光子激发区域的符合离子对产生（cipp）光谱。f++ F−信号显示一个旋转带头结构，对应于f2rydberg态越过离子对产生表面。光谱模拟和量子缺陷分析表征了5个新的分子Rydberg态（F2**）： 1个Π和4个Σ态。观察到的最低能量里德伯态谱（T0 = 125 999 cm−1）缺乏一些预测的旋转结构，这使得可以准确地确定离子对产生阈值为15.62294±0.00043 eV。利用众所周知的氟原子电离能和电子亲和能，这个数字得出基态F-F离解能为1.60129±0.00044 eV。在F2上进行了光电子光离子重合（PEPICO）实验，确定了f++ F的解离光电离阈值为19.0242±0.0006 eV。利用氟原子的电离能，可将其转换为F2离解能1.60132±0.00062 eV，进一步证实了上述cipp推导值。由于这两个实验都是独立的能量校准，它们的平均值可以达到1.60130±0.00036 eV，这个值可以用来推导氟原子的0 K生成热为77.251±0.017 kJ mol−1。后者与最新的活性热化学表（ATcT）值非常一致，但其准确性提高了近三倍。
Coincidence ion pair production (cipp) spectra of F2 were recorded on the DELICIOUS III coincidence spectrometer in the one-photon excitation region of 125 975–126 210 cm−1. The F+ + F− signal shows a rotational band head structure, corresponding to F2 Rydberg states crossing over to the ion pair production surface. Spectral simulation and quantum defect analysis allowed the characterization of five new molecular Rydberg states (F2**): one Π and four Σ states. The lowest-energy Rydberg state spectrum observed (T0 = 125 999 cm−1) lacked some of the predicted rotational structure, which allowed an accurate determination of the ion pair production threshold of 15.62294 ± 0.00043 eV. Using the well-known atomic fluorine ionization energy and electron affinity, this number leads to a ground state F–F dissociation energy of 1.60129 ± 0.00044 eV. Photoelectron photoion coincidence (PEPICO) experiments were also carried out on F2 and the dissociative photoionization threshold to F+ + F was determined as 19.0242 ± 0.0006 eV. Using the atomic fluorine ionization energy, this can be converted to an F2 dissociation energy of 1.60132 ± 0.00062 eV, further confirming the cipp-derived value above. Because the two experiments were independently energy-calibrated, they can be averaged to 1.60130 ± 0.00036 eV and this value can be used to derive the fluorine atom's 0 K heat of formation as 77.251 ± 0.017 kJ mol−1. This latter is in excellent agreement with the latest Active Thermochemical Table (ATcT) value but improves its accuracy by almost a factor of three.