Pitchimani Rajasekar, Burnham Alan K, Weeks Brandon L
Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, USA.
J Phys Chem B. 2007 Aug 9;111(31):9182-5. doi: 10.1021/jp073516e. Epub 2007 Jul 14.
Atomic force microscopy (AFM) has been successfully used to study the activation energy for evaporation of pentaerythritol tetranitrate (PETN) nanoislands formed by spin coating. These islands are annealed isothermally in the temperature range of 30-70 degrees C for a given time and are scanned with AFM in contact mode at room temperature. The volume of these islands does not change significantly up to about 35-40 degrees C indicating that sublimation is not significant below 40 degrees C. Above 40 degrees C, the islands start shrinking, and the rate of weight loss is analyzed as a function of temperature. The activation energy of evaporation using AFM was found to be similar to that for bulk PETN crystals using thermogravimetric analysis (TGA) at higher temperatures (110-135 degrees C). These results demonstrate that AFM is a useful tool to measure thermodynamic properties with a nanoscale probe.
原子力显微镜（AFM）已成功用于研究通过旋涂形成的季戊四醇四硝酸酯（PETN）纳米岛的蒸发活化能。这些岛在30-70摄氏度的温度范围内等温退火给定时间，并在室温下以接触模式用AFM进行扫描。这些岛的体积在约35-40摄氏度以下没有明显变化，表明在40摄氏度以下升华不明显。高于40摄氏度时，这些岛开始收缩，并将失重率作为温度的函数进行分析。发现在较高温度（110-135摄氏度）下，使用AFM测得的蒸发活化能与使用热重分析（TGA）测得的块状PETN晶体的蒸发活化能相似。这些结果表明，AFM是一种使用纳米级探针测量热力学性质的有用工具。
