...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Positional Isotope Exchange in HX center dot(H2O)(n) (X = F, I) Clusters at Low Temperatures
【24h】

Positional Isotope Exchange in HX center dot(H2O)(n) (X = F, I) Clusters at Low Temperatures

机译：低温下HX中心点（H2O）（n）（X = F，I）团簇中的位置同位素交换

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

We present molecular dynamics simulation results describing proton/deuteron exchange equilibria along hydrogen bonds at the vicinity of HX acids (X = F, I) in aqueous clusters at low temperatures. To allow for an adequate description of proton transfer processes, our simulation scheme resorted on the implementation of a multistate empirical valence bond hamiltonian coupled to a path integral scheme to account for effects derived from nuclear quantum fluctuations. We focused attention on clusters comprising a number of water molecules close to the threshold values necessary to stabilize contact-ion-pairs. For X = F, our results reveal a clear propensity of the heavy isotope to lie at the bond bridging the halide to the nearest water molecule. Contrasting, for X = I the thermodynamic stability is reversed and the former connectivity is preferentially articulated via the light isotope. These trends remain valid for undissociated and ionic descriptions of the stable valence bond states. The preferences are rationalized in terms of differences in the quantum kinetic energies of the isotopes which, in turn, reflect the extent of the local spatial confinements prevailing along the different hydrogen bonds in the clusters. In most cases, these features are also clearly reflected in the characteristics of the corresponding stretching bands of the simulated infrared spectra. This opens interesting possibilities to gauge the extent of the isotopic thermodynamic stabilizations and the strengths of the different hydrogen bonds by following the magnitudes and shifts of the spectral signals in temperature-controlled experiments, performed on mixed clusters combining H2O and HOD.
机译：我们目前描述分子动力学模拟结果描述质子/氘核交换平衡沿着氢键在附近的HX酸（X = F，I）在水性簇中的低温。为了充分描述质子转移过程，我们的模拟方案采用多状态经验价键哈密顿量的实现，再加上路径积分方案，以解决源自核量子涨落的影响。我们将注意力集中在包含许多水分子的簇上，这些分子接近稳定接触离子对所需的阈值。对于X = F，我们的结果表明，重同位素存在明显的倾向，即位于将卤化物桥接至最近的水分子的键上。相反，对于X ＝ 1，热力学稳定性是相反的，并且先前的连通性优选通过光同位素表达。这些趋势对于稳定价键态的未离解和离子描述仍然有效。根据同位素的量子动能的差异来合理化偏好，这又反映了沿着簇中不同氢键的局部空间限制的程度。在大多数情况下，这些特征也清楚地反映在模拟红外光谱的相应拉伸带的特征中。这通过跟踪在结合H2O和HOD的混合簇上进行的温度控制实验中的光谱信号的幅度和位移，为测量同位素热力学稳定程度和不同氢键的强度提供了有趣的可能性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号