The electronic band gap, i.e. the energy difference between the top of the valence band and the bottom of the conduction band, is widely recognized as the key property characterizing the electronic structure of bulk liquids and liquid solvents like water or ammonia. Here, the band gap of liquid ammonia at 270 K and 300 bar was studied with 2-photon ionization spectroscopy using the solvated electron primary yield as a near-infrared action-spectroscopic probe. The experimentally determined escape probability, which is the fraction of solvated electrons that is able to avoid geminate recombination within the first nanosecond after ionization, was used to extract a value of −(1.27 ± 0.03) eV for the vertical electron affinity of the liquid.

中文翻译：

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飞秒多光子电离光谱法探测液氨的带隙†

电子带隙，即价带顶部和导带底部之间的能量差，被广泛认为是表征大体积液体和液体溶剂（如水或氨）的电子结构的关键特性。此处，使用溶剂化的电子一次产率作为近红外作用光谱探针，通过2-光子电离光谱研究了液氨在270 K和300 bar下的带隙。实验确定的逸出概率是能避免电离后第一纳秒内发生萌芽重组的溶剂化电子比例，用于提取液体垂直电子亲和力的-（1.27±0.03）eV值。