Statement of Work Ranko Richert, ASU sub-award:"Dynamics of Vapor-deposited Glasses and Liquids" PI: Mark Ediger, University of Wisconsin-Madison, Department of Chemistry sub-contract PI: Ranko Richert, Arizona State University, Department of Chemistry and Biochemistry The main goal of the work carried out as sub-contract to the project on"Dynamics of Vapordeposited Glasses and Liquids"will focus on section 4.C and 4.D of the proposed research. Dielectric relaxation techniques have proven to be very effective tools for the characterization of liquid and glassy dynamics, partly due to the wide frequency range and high sensitivity of the method. In the context of dielectric experiments, one main goal is to establish an in situ dielectric setup capable of measuring the dynamics of thin films inside the vacuum chamber in which the films were grown by vapor deposition. To this end, existing equipment in the ASU lab will be assembled to facilitate physical vapor deposition in a simple apparatus (system limited to using low Tg, high vapor pressure materials). Films grown in this system will serve to test and improve the dual-channel technique with interdigitated electrode pairs as an in-situ measurement. Initial experiments will be performed to establish the resolution of this approach at low temperatures, which is expected to surpass significantly the known performance above room temperature. The system will then be used to characterize stable films of isopropylbenzene and other low Tg glass formers, as the ASU setup can reach temperatures well below the UW-Madison laboratory limit, i.e. as low as 30 K. At a later stage, the ASU system will be used to explore whether the intermediate range order of monohydroxy alcohols interferes with the ability to form ultra-stable glasses. In a second step, a technology transfer will be conducted in order to facilitate high-resolution dielectric measurements, in-situ, in the Madison laboratory. The combination of low frequencies and small molecular dipole moments for some samples require dedicated transimpedance amplifiers, which have been designed in the Richert group and these can be home built. The Richert group will also assist in designing the software required to automate the dielectric measurements at UW-Madison. As this is non-commercial equipment, we will train the Madison personnel on the use of the dielectric setup and on the optimization of sample/cell properties and data analysis. This training will include the setup of dielectric work using interdigitated electrodes which facilitate dielectric probing of films within the deposition chamber. In close collaboration with the Ediger group, secondary relaxation frequencies and amplitudes will be measured as probes of ultra-stable versus normal glassy state properties. Measurement systems will be optimizes in resolution and frequency bandwidth where necessary for detecting secondary mode far below Tg, and measurements will be performed at ASU if molecular glasses are of interest with deposition temperatures below the UW-Madison temperature range.
|Effective start/end date||9/15/13 → 8/31/16|
- National Science Foundation (NSF): $141,328.00
in situ measurement