一种简单而有效的防止高温光谱实验中显微物镜温度过高的装置:空气吹扫装置

地球内部是一个高温高压环境。温度对于矿物的物理-化学性质有着非常重要的影响。随着温度的升高,矿物的分子振动、弹性模量、地震波波速等诸多性质有可能发生显著的变化,从而对地球内部的相关物理-化学过程产生非常重要的影响。高温谱学研究(如高温红外及高温拉曼)对了解矿物在高温下的物理-化学性质有着非常重要的意义。尽管高温谱学研究中常用的加热台带有冷却装置,能够确保加热台在很高温度下也能正常运转(如1 500℃),然而加热元件在高温下辐射出的大量热量可能使相关光聚焦物镜系统的温度急剧升高,从而造成热损伤,进而限制了高温谱学研究的温度范围。本文的创新点在于为克服这个困难,我们提供了一种简单而有效的防止高温光谱实验中显微物镜温度过高的装置,从而扩展高温谱学研究的温度范围。通过在物镜系统的附近添加了一套空气吹扫装置,加速空气流动而带走多余的热量,从而降低物镜系统的温度。测试表明:尽管这一装置非常简单,但却非常有效;当实验温度为~1 000℃时,物镜下表面的温度由原来的~235℃下降到~68℃。利用该空气吹扫装置,我们对镁橄榄石进行了温度高达~1 300℃的原位拉曼光谱研究,实验结果与其他研究报道的结果一致。这一事实表明,通过添加该空气吹扫装置,高温谱学研究可以比较容易地在超过1 300℃的高温下进行,所用物镜系统基本没有热损伤,从而避免采用能承受更高温度的不同材质的物镜或者运用长焦距物镜的昂贵办法。

A Simple but Effective Device to Avoid Obj ective Lens Overheating:An Air Blower Device

The interior of the Earth is a high temperature and high pressure environment.High temperatures cause important changes in the physical and chemical properties of minerals.An increase in temperature leads to significant changes in the molec-ular and lattice vibrations,elasticity,and seismic velocity of minerals.The high temperature vibrational spectroscopy (infrared and Raman)used to study these changes can provide highly significant understanding of the Earth’s interior.During high tem-perature spectroscopy,the heating device that is used to heat the sample can work at a very high temperature (e.g.,1 500 ℃) because it has a cooling device surrounding it that is used to prevent the temperature of its environments from getting too high. However,radiation from its heating elements is intense and this will shine on and heat the objective lens of the focusing system for the spectroscopic light source,and this would result in damage to the lens.Thus,to avoid damage to the obj ective lens,an upper limit is placed on the heater temperature.The significance of this work is that it presents a method to exceed the present instrument’s temperature limit so that we can perform in situ spectroscopy on samples at higher temperatures.This work ex-
tended the temperature limit for the sample to a higher temperature by using an air blower around the obj ective lens to create a gas flow around it.The gas flow serves to remove heat from the obj ective lens by forced convection and its turbulent flow also served to increase the rate of heat transport from the lens to the moving gas stream,which together prevented overheating of the obj ective lens.Our results have shown that although this device is simple,it was highly effective:for a sample temperature of 1 000 ℃,the objective lens temperature was reduced from ~235 to ~68 ℃.Using this device,we performed in situ high tem-perature Raman spectroscopy of forsterite up to a sample temperature of 1 300 ℃.The results agreed well with previous studies and demonstrated that with our simple air blower device,we can perform in situ high temperature spectroscopy up to 1 300 ℃without damaging the obj ective lens and without expensive components like a high temperature composite obj ective lens or a long focus obj ective lens.