Predissociation measurements of bond dissociation energies: VC, VN, and VS
Predissociation measurements of bond dissociation energies: VC, VN, and VS
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DOI：
10.1063/1.4953782
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发表时间：
2016-06-21
影响因子：
4.4
通讯作者：
Morse, Michael D.
中科院分区：
文献类型：
--
作者：
Johnson, Eric L.;Davis, Quincy C.;Morse, Michael D.
使用共振双光子电离光谱观察到喷射冷却 VC、VN 和 VS 的拥挤电子光谱中预解离的突然开始。有人认为，由于这些分子中电子态的高密度，预解离阈值出现在产生处于基态电子态的分离原子的热化学阈值处。因此，测量的阈值代表键解离能。使用该方法，获得了D-0(VC) = 4.1086(25) eV、D-0(VN) = 4.9968(20) eV和D-0(VS) = 4.5353(25) eV的键解离能。根据这些值，可得出生成焓：Delta H-f,H-0K 度(VC(g)) = 827.0 +/- 8 kJ mol(-1)，Delta H-f,H-0K 度(VN(g)) = 500.9 +/- 8 kJ mol(-1)，Delta H-f,H-0K 度(VS(g)) = 349.3 +/- 8 kJ·摩尔(-1)。使用热化学循环和众所周知的 V、VC 和 VN 电离能，我们的结果还提供 D-0(V+-C) = 3.7242(25) eV 和 D-0(V+-N) = 4.6871(20) eV。将这些值与之前的测量值和计算结果进行比较。这些键解离能的精确度使它们成为测试计算化学方法的良好候选者，特别是那些采用密度泛函理论的方法。由 AIP 出版社出版。
The abrupt onset of predissociation in the congested electronic spectra of jet-cooled VC, VN, and VS has been observed using resonant two-photon ionization spectroscopy. It is argued that because of the high density of electronic states in these molecules, the predissociation threshold occurs at the thermochemical threshold for the production of separated atoms in their ground electronic states. As a result, the measured threshold represents the bond dissociation energy. Using this method, bond dissociation energies of D-0(VC) = 4.1086(25) eV, D-0(VN) = 4.9968(20) eV, and D-0(VS) = 4.5353(25) eV are obtained. From these values, enthalpies of formation are derived as Delta H-f,H-0K degrees(VC(g)) = 827.0 +/- 8 kJ mol(-1), Delta H-f,H-0K degrees(VN(g)) = 500.9 +/- 8 kJ mol(-1), and Delta H-f,H-0K degrees(VS(g)) = 349.3 +/- 8 kJ mol(-1). Using a thermochemical cycle and the well-known ionization energies of V, VC, and VN, our results also provide D-0(V+-C) = 3.7242(25) eV and D-0(V+-N) = 4.6871(20) eV. These values are compared to previous measurements and to computational results. The precision of these bond dissociation energies makes them good candidates for testing computational chemistry methods, particularly those that employ density functional theory. Published by AIP Publishing.