Kechoindi S, Ben Yaghlane S, Mogren Al Mogren M, Bodi A, Hochlaf M
Université Gustave Eiffel, COSYS/IMSE, 5 Bd Descartes 77454, Champs-sur-Marne, France.
Laboratoire de Spectroscopie Atomique, Moléculaire et Applications - LSAMA, Université de Tunis El Manar, Tunis, Tunisia.
Phys Chem Chem Phys. 2024 Sep 25;26(37):24656-24666. doi: 10.1039/d4cp03015j.
Advanced theoretical methodologies and photoelectron photoion coincidence spectroscopy were used to investigate the photoionization of ethanolamine in the 8-18 eV energy range. We identified the low-lying cation conformers and the excited cation electronic states after vertical excitation from the most stable neutral conformer computationally. The TPES is composed of broad, structureless bands because of unfavorable Franck-Condon factors for origin transitions upon ionization, populating the D-D cationic states from the most stable neutral conformer, g'Gg'. The adiabatic ionization energy of ethanolamine is calculated at 8.940 ± 0.010 eV, and the 0 K appearance energies of aminomethylium, NHCH (+CHOH), and methyleneammonium, NHCH (+HCO), are determined experimentally to be 9.708 ± 0.010 eV and 9.73 ± 0.03 eV, respectively. The former is used to re-evaluate the ethanolamine enthalpy of formation in the gas and liquid phases as Δ⊖298K[NH(CH)OH, g] = -208.2 ± 1.2 kJ mol and Δ⊖298K[NH(CH)OH, l] = -267.8 ± 1.2 kJ mol. This represents a substantial correction of the previous experimental determination and is supported by calculations.
采用先进的理论方法和光电子-光离子符合光谱技术，研究了乙醇胺在8-18 eV能量范围内的光电离过程。我们通过计算确定了从最稳定的中性构象垂直激发后的低能阳离子构象和激发态阳离子电子态。由于电离时起始跃迁的弗兰克-康登因子不利，导致总光电子能谱（TPES）由宽的、无结构的谱带组成，从最稳定的中性构象g'Gg'填充到D-D阳离子态。计算得出乙醇胺的绝热电离能为8.940±0.010 eV，实验测定氨基甲基正离子NHCH(+CHOH)和亚甲基铵NHCH(+HCO)的0 K出现能分别为9.708±0.010 eV和9.73±0.03 eV。前者用于重新评估乙醇胺在气相和液相中的生成焓，分别为Δ⊖298K[NH(CH)OH, g] = -208.2±1.2 kJ mol和Δ⊖298K[NH(CH)OH, l] = -267.8±1.2 kJ mol。这代表了对先前实验测定的重大修正，并得到了计算结果的支持。
