Novel apparatus simultaneously and fully characterizes nanoscale reactions
Novel apparatus simultaneously and fully characterizes nanoscale reactions lead image
Chemical reactions that occur in nanoscale systems can produce enough heat and stress to alter the chemical and physical properties of the material. Thus, measuring the mechanical, optical and thermal properties of these systems is important for device design. Relevant real-world applications include energy and information storage, catalysis and sensing.
Murray et al. present a novel apparatus designed to take a whole range of measurements into account in order to create a complete picture of nanoscale reactions. It combines a quartz crystal microbalance, used to detect changes of mass due to chemical or physical processes, in a pressure- and temperature-controlled environment with instrumentation for optical, calorimetric and electrical measurements.
The authors originally needed a system to observe hydrogen uptake in palladium, but they also wanted it to be broadly useful for a variety of applications. Once they decided on a system that would measure several properties at once, each of the subsystems took several months of testing and modification to perfect.
The apparatus performs simultaneous mass, stress and thermal measurements on a single sample to control for sample-to-sample variation and increase overall accuracy. As an example device operation, the authors observed a palladium hydrogenation reaction. The results demonstrated that it can resolve changes in curvature of 0.001 m−1 (corresponding to a stress of 0.006 millipascal per micron of film thickness), changes in areal mass of 13 nanograms per centimeter-squared and changes in optical reflectivity of 0.3 percent. It can also resolve heat measurements with 150-microwatt accuracy.
For future work, they intend to use the apparatus to study hydrogen uptake into different metals as well as the changes in stress during polymer curing.
Source: “Apparatus for combined nanoscale gravimetric, stress, and thermal measurements,” by Joseph B. Murray, Kevin J. Palm, Tarun C. Narayan, David K. Fork, Seid Sadat, and Jeremy N. Munday, Review of Scientific Instruments (2018). The article can be accessed at https://doi.org/10.1063/1.5040503 .
