Research On Chemical Reactivity Of Diatomic Molecular Fluid And Molecular Interaction Potential At High Pressure And High Temperatures

In this work, the chemical reactivity of hydrogen fluid is investigated at high pressure and high temperature (lOOGPa, 3500K). And also, Ab initio calculation method of quantum-chemical theory is adopted to study the contribution of 3-body interactions to the effective pair potential between nitrogen molecules. Main points are summarized as follows:1) Optical radiation and electrical conductance of Al/H₂/Al₂O₃ has been measured under multiple shock compression. Anomalous emission and conductance during shock loading and unloading are observed for the first time.2) Qualitative explanation of such anomalous phenomena has been put forward from the point of chemical reaction. It is concluded that there may exist a stable phase of aluminum-hydride under the extreme condition. The physical and chemical behavior of Al/H₂ system during shock compressions is deduced: the gaseous hydrogen sample is compressed by multi-Shockwave→some hydrogen molecules dissociate to atoms (the conductance increases)→aluminum base plate absorbs hydrogen atoms (conductance of base plate decreases and some quantity of heat is released) →all of hydrogen are absorbed, and a layer of aluminum hydride is formed (the conductance of base plate keeps unchanged) →the rarefaction wave arrives at aluminum hydride, and the atomic hydrogen is released from the base plate, and then the atoms combine to molecules (theconductance of base plate recovers to high level, and lots of heat is released).3) The axially-symmetric magnetic technique (ASM) is adopted to monitor the conductance change of Al/H₂ under shock compression condition. Based on finite element analysis, a computation program is written to calculate the electric current distribution in the moving base plate of finite geometry. The experiment results demonstrate the-conductance change of the sample can be detected by ASM technique.4) Based on ab initio method of q(?)ntum-chemical theory, the 3-body correlation among nitrogen molecules is firstly investigated. It is found that three-body contributions obviously soften the average pair potential.Under the pressure which the nitrogen molecular dissociation can be neglected, the theoretical Hugoniot is consistent with the experimental data.