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Physical vapor deposition can prepare organic glasses with high kinetic stability. When heated, these glassy solids slowly transform into supercooled liquid in a process known as rejuvenation. In this study, we anneal vapor-deposited glasses of methyl-m-toluate for 6 h at 0.98Tg to observe rejuvenation using dielectric spectroscopy. Glasses of moderate stability exhibited partial or full rejuvenation in 6 h. For highly stable glasses, prepared at substrate temperatures of 0.85Tg and 0.80Tg, the 6 h annealing time is ∼2% of the estimated transformation time, and no change in the onset temperature for the α relaxation process was observed, as expected. Surprisingly, for these highly stable glasses, annealing resulted in significant increases in the storage component of the dielectric susceptibility, without corresponding increases in the loss component. These changes are interpreted to indicate that short-term annealing rejuvenates a high frequency relaxation (e.g., the boson peak) within the stable glass. We compare these results to computer simulations of the rejuvenation of highly stable glasses generated by using the swap Monte Carlo algorithm. The in silico glasses, in contrast to the experiment, show no evidence of rejuvenation within the stable glass at times shorter than the alpha relaxation process. 

Glassy films of methyl-m-toluate have been vapor deposited onto a substrate equipped with interdigitated electrodes, facilitating in situ dielectric relaxation measurements during and after deposition. Samples of 200 nm thickness have been deposited at rates of 0.1 nm/s at a variety of deposition temperatures between 40 K and Tg = 170 K. With increasing depth below the surface, the dielectric loss changes gradually from a value reflecting a mobile surface layer to that of the kinetically stable glass. The thickness of this more mobile layer varies from below 1 to beyond 10 nm as the deposition temperature is increased, and its average fictive temperature is near Tg for all deposition temperatures. Judged by the dielectric loss, the liquid-like portion of the surface layer exceeds a thickness of 1 nm only for deposition temperatures above 0.8Tg, where near-equilibrium glassy states are obtained. After deposition, the dielectric loss of the material positioned about 5–30 nm below the surface decreases for thousands of seconds of annealing time, whereas the bulk of the film remains unchanged. 

This project uses an ecological belonging intervention approach [1] that requires one-class or one- recitation/discussion session to implement and has been shown to erase long-standing equity gaps in achievement in introductory STEM courses. However, given the wide social and cultural heterogeneity across US university contexts (e.g., differences in regional demographics, history, political climates), it is an open question if and how the intervention may scale. This project brings together an interdisciplinary team across three strategically selected universities to design, test, and iteratively improve an approach to systematically identify which first and second year courses would most benefit from the intervention, reveal student concerns that may be specific to that course, adapt the intervention to address those concerns, and evaluate the universality versus specificity of the intervention across university contexts. This systematic approach also includes persuasion and training processes for onboarding the instructors of the targeted courses. The instructor onboarding and the intervention adaptation processes are guided by a theory-of-action that is the backbone of the project’s research activities and iterative process improvement. A synergistic mixture of qualitative and quantitative methods is used throughout the study. In this paper, we describe our theoretical framing of this ecological belonging intervention and the current efforts of the project in developing customized student stories for the intervention. We have conducted focus groups across each of the partner institutions (University of Pittsburgh, Purdue University, and University of California Irvine). We describe the process of developing these contextually relevant stories and the lessons learned about how this ecological belonging intervention can be translated across institutional contexts and for various STEM majors and systemically minoritized populations. The results of this work can provide actionable strategies for reducing equity gaps in students' degree attainment and achievement in engineering. 

By measuring the increments of dielectric capacitance (Δ C ) and dissipation (Δtan  δ ) during physical vapor deposition of a 110 nm film of a molecular glass former, we provide direct evidence of the mobile surface layer that is made responsible for the extraordinary properties of vapor deposited glasses. Depositing at a rate of 0.1 nm s −1 onto a substrate at T dep = 75 K = 0.82 T g , we observe a 2.5 nm thick surface layer with an average relaxation time of 0.1 s, while the glass growing underneath has a high kinetic stability. The level of Δtan  δ continues to decrease for thousands of seconds after terminating the deposition process, indicating a slow aging-like increase in packing density near the surface. At very low deposition temperatures, 32 and 42 K, the surface layer thicknesses and mobilities are reduced, as are the kinetic stabilities.