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首页> 外文期刊>The Journal of Chemical Physics >Energy barrier of proton transfer at ice surfaces
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Energy barrier of proton transfer at ice surfaces

机译：冰表面质子转移的能垒

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摘要

We estimated the energy barrier of proton transfer on ice film surfaces through the measurement of the H/D exchange kinetics of H_2 O and D_2 O molecules. The isotopomeric populations of water molecules and hydronium ions on the surface were monitored by using the techniques of reactive ion scattering and low energy sputtering, respectively, along the progress of the H/D reaction. When hydronium ions were externally added onto an ice film at a temperature of 70 K, a proton was transferred from the hydronium ion mostly to an adjacent water molecule. The proton transfer distance and the H/D exchange rate increased as the temperature increased for 90-110 K. The activation energy of the proton transfer was estimated to be 10±3 kJ mol~(-1) on a polycrystalline ice film grown at 135 K. The existence of a substantial energy barrier for proton transfer on the ice surface agreed with proton stabilization at the surface. We also examined the H/D exchange reaction on a pure ice film surface at temperatures of 110-130 K. The activation energy of the reaction was estimated to be 17±4 kJ mol~(-1), which was contributed from the ion pair formation and proton transfer processes on the surface.
机译：我们通过测量H_2 O和D_2 O分子的H / D交换动力学，估计了质子在冰膜表面转移的能垒。随着H / D反应的进行，分别使用反应性离子散射和低能溅射技术监测了表面上水分子和水合氢离子的同分异构体。当将水合氢氧根离子在70 K的温度下外部添加到冰膜上时，质子从水合氢氧根离子大部分转移到相邻的水分子上。在90-110 K的温度下，质子的转移距离和H / D交换速率随温度的升高而增加。估计在90〜110 K的温度下生长的多晶冰膜上质子转移的活化能为10±3 kJ mol〜（-1）。 135 K.在冰表面存在大量的质子转移能垒，与表面的质子稳定相吻合。我们还研究了在110-130 K的温度下在纯冰膜表面上的H / D交换反应。反应的活化能估计为17±4 kJ mol〜（-1），这是由离子贡献的对形成和质子转移过程在表面上。

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