Accessing Thermal Phonon States Within Nanoscale Cavities
Bibliographic record
Abstract
Nanoscale cavities subjected to thermal gradients offer unique opportunities to investigate physical and chemical properties in extremely confined spaces. For instance, determining the contribution of conduction phonon channels to the thermal conductance within a cavity represents an ongoing scientific challenge [1]. Studying the thermal effects on coupled surface phonon requires the use of local spectroscopy probes with nanoscale thermal sensitivity [2]. We will discuss spatially-resolved high energy resolution EELS studies in nanoscale cavities subjected to a thermal gradient. Our work focuses on understanding the role of temperature in the behavior of surface phonon coupling and inelastic electron scattering from phonons. We fabricated cavities with gaps ranging between 5 and 150 nm, which were subjected to temperatures between 300 – 1000 K using a dedicated heating holder. We used a Nion UltraStem equipped with an aberration corrector and monochromator to study coupled surface phonons within nanogaps using a ∼1.5-2 Å probe with an energy resolution of ∼10 meV, at 60 kV. A large variety of coupled phonon polariton modes were detected within the cavity indicating the existence of several available channels for heat transfer processes. We mapped out the spatial distribution of scattering signal across the cavity nanogaps revealing a strong temperature-dependent behavior, which suggests a complex interplay between thermal and surface phonon behavior. The scattering probability across the gap exhibits a parabolic distribution which is strongly dependent on both the gap distance and the temperature profile across the gap (see Fig. 1). The temperature of the cavity system was measured locally with high precision [3]. We developed a theoretical model to calculate the inelastic electron scattering from coupled surface phonons sustained in semi-infinite flat surfaces spaced by a gap, each surface at different temperatures. The results offer insights into the spatial distribution of each channel/phonon modes across the cavity gap and considerations for temperature-dependent dielectric functions. Our work represents progress towards the interpretation of temperature-dependent EELS data and understanding of the interplay between thermal and phonon properties of coupled nanostructures [4]. Surface phonon polariton mapping of a nanoscale cavity. (a) Spatially resolved EELS map obtained in a cavity with a 102 nm gap at room temperature (ΔT = 0). b) EELS map obtained in cavity subjected to a gradient temperature across the gap (ΔT ≠ 0). Notice the asymmetric behavior across the gap. Maps were built using contributions from all surface phonon modes within a 20 meV band.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".