摘要
报道关于地球内部极端条件下的流体实验研究的最新进展。使用金刚石压砧结合各种谱学方法及同步辐射光源技术,在高温超高压条件下原位直接测量物质的结构和性质,已经获得分子-原子尺度信息新的实验数据。本项工作使用金刚石压砧对高压(10GPa)和高温高压(800℃,3GPa)条件下的NaCl-H2O进行红外谱原位直测,研究了高压和高温高压下水分子结构,发现水分子的O—H振动特征峰频率随温度向高波数变化,而且,在临界态区域时水分子间的氢键网格被破坏。实验说明:地球内部流体性质由深到浅不断变化,如水的密度、介电常数等物理参数随温度压力而改变,在临界态出现突变。这些变化可以用高压高温的物质的各种谱学特征来表征。水的性质与它的分子结构、分子振动有关。在跨越临界区时水的性质异常涨落是由水分子结构异常变化、分子振动形式变化和氢键网格破坏所导致的。从分子尺度认识地球内部流体在极端条件下的性质和高压原位实验观测有助于我们进一步了解地球深部物质的性质及其相互作用,有助于认识深部过程。
Recent ultra-high pressure and high temperature experiments provide a new opportunity to gain an insight into the fluids, fluid and matter interactions in the extreme conditions of the deep Earth interior. In-situ observations of the matter under ultra-high pressure and high temperature conditions as in the Earth interior by using diamond anvil cell connected to spectrometer and microscope, combined with synchrotron radiation technique, may obtain new data and message of their molecular structures and natures in atomic scale and in kinetics. The nature of Earth fluids would be changed by the variations of the temperatures and pressures of their locations. It is well known that the properties of water in the critical region may show anomalies in many of its physical properties. For example, the density or dielectric constant of water may drop with increasing temperature. The molecule structures of aqueous solutions （NaCl-H2O） at high temperatures and pressures（800℃,3 GPa） have been examined by in-situ observation using diamond anvil cell connected to FT-IR spectrometer combining with synchrotron radiation technique. The sharp and strong O--H stretching vibration at 330℃ near the critical point of water proves the break down of the hydrogen bonding network. Within and near the critical region, the rapid decrease in the dielectric constant and density of water results from the destruction of the hydrogen bond network of the water molecules. The O-H vibration frequency increases with temperature. Experiments demonstrate that the nature and the structure of the Earth fluids will change with depth. As passing through the critical state, the anomalous properties of fluids will be affected by the variations of water molecule vibrations and the break down of hydrogen bond network in the critical state.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2009年第1期41-52,共12页
Earth Science Frontiers
基金
国土资源部项目(20010302
200010200172)
科学技术部项目(2003AA612020-3
2001DEA20023
2001DEA30041
2003DEA2C021
G1999043212)
国家自然科学基金项目(4003011
49473196
20373064)
财政部专项(140102)
科学技术部中央院所公益基金项目(K2007-1-13)
关键词
地球内部高温超高压
临界态
流体性质
分子谱
ultra-high pressure and high temperature in Earth interior
critical state
fluid nature
molecular spectroscopy
