The glass transitions of amorphous ices as well as of aqueous phosphoric acid solutions were reported to display very large ¹H/²H isotope effects. Using dielectric spectroscopy, in both types of glassformers for equimolar protonated/deuterated mixtures an almost ideal isotope-mixing behavior rather than a bimodal relaxation is found. For the amorphous ices this finding is interpreted in terms of a glass-to-liquid rather than an orientational glass transition scenario. Based on calorimetric results revealing that major ¹⁶O/¹⁸O isotope effects are missing, the latter scenario was previously favored for the amorphous ices. Considering the dielectric results on ¹⁸O substituted amorphous ices and by comparison with corresponding results for the aqueous phosphoric acid solutions, it is argued that the present findings are compatible with the glass-to-liquid scenario. To provide additional information regarding the deeply supercooled state of ¹H/²H isotopically mixed and ¹⁸O substituted glassformers, the aqueous phosphoric acid solutions are studied using shear mechanical spectroscopy as well, a technique which so far could not successfully be applied to characterize the glass transitions of the amorphous ices.

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同位素对无定形冰和磷酸水溶液动力学的影响

据报道，无定形冰和磷酸水溶液的玻璃化转变显示出非常大的¹ H/ ² H 同位素效应。使用介电光谱，在等摩尔质子化/氘化混合物的两种类型的玻璃形成剂中，发现了几乎理想的同位素混合行为，而不是双峰弛豫。对于无定形冰，这一发现被解释为玻璃到液体而不是定向玻璃化转变情景。基于显示主要¹⁶ O/ ¹⁸ O 同位素效应缺失的量热结果，后一种情况以前更适合无定形冰。考虑到^{18 日的介电结果}O 取代无定形冰，并与磷酸水溶液的相应结果进行比较，有人认为目前的发现与玻璃到液体的情况兼容。为了提供有关¹ H/ ² H 同位素混合和¹⁸ O 取代的玻璃形成剂的深度过冷状态的更多信息，还使用剪切机械光谱研究了磷酸水溶液，该技术迄今为止无法成功地应用于表征无定形冰的玻璃化转变。