Small wavenumber shift Raman spectroscopy of water and heavy water under negative pressure

制造了具有3个蓝宝石窗口的金属Berthelot管，用于负压下的水的拉曼光谱，但其产生的压力仅为-30巴，这太低。对原因进行了调查，并确定了三个主要调查结果。(1)在水Berthelot系统中选择金属的电化学标准是不应使用被水腐蚀的金属。铝与水反应产生氢气，这甚至抑制了负压的产生。然而，这一标准不适用于有机液体。(2)试样室壁面积越小，负压随温度循环的增加速率越快。这是因为空化核的数量成比例地较小。(3)在超临界水中对金属进行预处理在最初的几个循环中产生约-120巴的负压。如果没有这一点，通常需要2周进行约1000个周期。如果在预处理之前对高压釜本身进行脱气，则可以获得负压的进一步升高。最后一份声明仍在调查中。

A metal Berthelot tube having 3 sapphire windows was made for Raman spectroscopy of water under negative pressure, but it yielded oniy -30 bar which was too low. The causes were investigated and three key findings were established. (1) An electrochemical criterion for selecting metals in a water Berthelot system is that metals which are corroded with water should not be used. Aluminum reacts with water to produce hydrogen gas which inhibited even generation of negative pressure. This criterion, however, was not applied to organic liquids. (2) The smaller the area of specimen chamber wall, the faster the rate of increase in negative pressure with temperature cycles. This is because the number of cavitation nuclei is proportionally smaller. (3) Pre-treatment for metals under supercritical water yielded negative pressure of around-120 bar in initial a few cycles. Without this it used to take 2 weeks for carrying out ca.1000 cycles. Further rise in negative pressure would be attained if the autoclave itself was degassed before the pre-treatment. The last statement is still being investigated.