We have performed core level photoemission spectroscopy of gaseous acetylacetone, its fully deuterated form, and two derivatives, benzoylacetone and dibenzoylmethane. These molecules show intramolecular hydrogen bonds, with a proton located in a double-well potential, whose barrier height is different for the three compounds. This has allowed us to examine the effect of the double-well potential on photoemission spectra. Two distinct O 1s core hole peaks are observed, previously assigned to two chemical states of oxygen. We provide an alternative assignment of the double-peak structure of O 1s spectra by taking full account of the extended nature of the wave function associated with the nuclear motion of the proton, the shape of the ground and final state potentials in which the proton is located, and the nonzero temperature of the samples. The peaks are explained in terms of an unusual Franck–Condon factor distribution.

中文翻译：

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低势垒，双势阱中质子的量子效应：乙酰丙酮的核心能级光发射光谱

我们已经对气态乙酰丙酮（完全氘化的形式）和两种衍生物苯甲酰基丙酮和二苯甲酰基甲烷进行了核心能级光发射光谱分析。这些分子显示出分子内氢键，质子位于双阱电势中，这三种化合物的势垒高度不同。这使我们能够检查双阱电势对光发射光谱的影响。观察到两个不同的O 1s核心孔峰，这些峰先前分配给氧气的两个化学状态。通过充分考虑与质子核运动有关的波函数的扩展性质，质子的基态和最终态势，我们提供了O 1s光谱双峰结构的替代分配。位置，以及样品的非零温度。