Gibbard Jemma A
Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom.
J Phys Chem A. 2024 Dec 26;128(51):11005-11011. doi: 10.1021/acs.jpca.4c06679. Epub 2024 Dec 11.
Photoelectron imaging of the doubly deprotonated ethylenediaminetetraacetic acid dianion (EDTA) at variable wavelengths indicates two electron loss pathways: direct detachment and thermionic emission from monoanions. The structure of EDTA is also investigated by electronic structure calculations, which indicate that EDTA has two intramolecular hydrogen bonds linking a carboxylate and carboxylic acid group at either end of the molecular backbone. The direct detachment feature in the photoelectron spectrum is very broad and provides evidence for a dissociative photodetachment, where decarboxylation occurs rapidly after electron loss. Near 0 eV kinetic energy electrons are only observed in the photoelectron spectrum of EDTA at ν = 3.49 eV (high laser fluence), providing evidence for secondary electron loss via a two-photon process, mediated by an excited state of the decarboxylated anion, and likely resulting in a cyclic neutral product.
在可变波长下对双去质子化乙二胺四乙酸二价阴离子（EDTA）进行光电子成像，结果表明存在两种电子损失途径：直接脱离和单阴离子的热离子发射。还通过电子结构计算对EDTA的结构进行了研究，结果表明EDTA具有两个分子内氢键，它们连接着分子主链两端的一个羧酸盐基团和一个羧酸基团。光电子能谱中的直接脱离特征非常宽，这为解离光脱离提供了证据，即电子损失后迅速发生脱羧反应。仅在ν = 3.49 eV（高激光通量）时EDTA的光电子能谱中观察到近0 eV动能的电子，这为通过双光子过程发生的二次电子损失提供了证据，该过程由脱羧阴离子的激发态介导，并且可能产生环状中性产物。
