Experimental Studies of Vapor-Deposited Water-Ice Films Using Grazing-Angle FTIR-Reflection Absorption Spectroscopy
Experimental Studies of Vapor-Deposited Water-Ice Films Using Grazing-Angle FTIR-Reflection Absorption Spectroscopy
复制标题
使用掠角 FTIR 反射吸收光谱法进行气相沉积水冰膜的实验研究
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
M. Robinson
中科院分区：
文献类型：
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作者：
M. Zondlo;T. Onasch;M. Warshawsky;M. Tolbert;G. Mallick;P. Arentz;M. Robinson
用掠入角傅里叶变换红外反射吸收光谱监测了94~120K范围内气相沉积H2O−冰膜中的自由OH伸展(或“悬挂键”)。冰膜厚度和我们的仪器对水−冰分子的灵敏度是通过使用氦−霓虹灯的光学干涉来确定的。这些校准表明，本研究中观察到的悬挂键信号表明了无定形冰块中存在的微孔的表面。在快速冰生长条件下，在94K下观察到最大的悬键信号(对应于最多的微孔)，而在缓慢生长条件下，在120K下观察到最小的悬键信号。利用薄膜生长过程中悬键信号对温度和压力的依赖关系，估算了水在无定形冰上的扩散势垒。我们测得EDIF的上限为4.2(±0.5)千卡·摩尔-1，与理论推导的EDIF=2.5千卡·摩尔-1的值一致.
Grazing-angle Fourier transform infrared reflection absorption spectroscopy was used to monitor the free OH stretch (or “dangling bond”) in vapor-deposited H2O−ice films between 94 and 120 K. Ice film thicknesses and the sensitivity of our instrument to water−ice molecules were determined by optical interference using a helium−neon laser. These calibrations indicate that the dangling bond signals observed in the present study are indicative of the surfaces of micropores present within the amorphous ice bulk. The largest dangling bond signal (corresponding to the largest number of micropores) was observed at 94 K under conditions of fast ice growth while the smallest signal was observed at 120 K under conditions of slow growth. The temperature and pressure dependence of the dangling bond signal during film growth was used to estimate a barrier to diffusion (Edif) for H2O on amorphous ice. We measured an upper limit of Edif = 4.2 (±0.5) kcal mol-1, consistent with a theoretically derived value of Edif = 2.5...