Electron–Nuclear Double Resonance¶
Detect nuclear-spin transitions through their effect on a coupled electron-resonance signal to resolve local hyperfine interactions.
Core Idea¶
Electron–nuclear double resonance (ENDOR) excites nuclear spins coupled to a paramagnetic electron and detects the resulting change through an electron-resonance signal. It can reveal hyperfine interactions that are crowded or unresolved in ordinary EPR. Continuous-wave and pulsed implementations share this coupled two-resonance identity.[ref-c3c6284daa06][ref-e0a1a853f99f]
Scope of Application¶
ENDOR applies to paramagnetic centers in solids, semiconductors and molecular systems when electron and nuclear spins couple detectably. CW experiments may monitor a saturated EPR intensity; pulsed experiments can monitor an electron echo, while an optically assisted silicon experiment used an Auger-electron/photoconductive electron-state readout. The seed's CW desaturation account is one variant, not the general definition.[ref-e0a1a853f99f][ref-8cb304b2393c]
Clarity¶
The nuclear transition is driven by RF excitation but detected through the electron response. That distinguishes ENDOR from EPR without RF drive and from direct NMR. Franke and colleagues' enriched-²⁸Si phosphorus experiment observed two RF resonances through electrical donor-state readout and fitted A=117.52(2) MHz; it was not echo-detected ENDOR. By contrast, Tyryshkin and colleagues' ¹⁴N@C₆₀ Davies experiment used an electron echo and reported a=15.7 MHz with nuclear-relaxation-limited visibility. A spectral line constrains coupling; assigning geometry still requires a model and corroboration.[ref-8cb304b2393c][ref-e9fc93e29db8]
Manages Complexity¶
Moving some information from a broad electron line into nuclear-frequency space can separate otherwise overlapping hyperfine effects. The gain is conditional: RF bandwidth, relaxation and weak signal may hide couplings even when nuclei are present.[^ref-e0a1a853f99f]
Abstract Reasoning¶
Establish an electron-spin-dependent readout, apply RF excitation to candidate nuclear transitions, and observe whether electron intensity, echo or validated electrical signal changes. Interpret line positions using a spin model and test alternative assignments. No response under one sequence does not prove no coupling exists.[ref-e9fc93e29db8][ref-8cb304b2393c]
Knowledge Transfer¶
The double-resonance relation transfers from a crystal defect to a silicon donor or molecular radical, but nuclear assignments and measurement windows depend on the spin system. The broad indirect-measurement idea is not enough to make ENDOR a prime. Its strict DAG relation to Resonance is a prerequisite relation: ENDOR requires coupled frequency-selective resonant responses but is not a subtype of one resonance.
[^ref-c3c6284daa06]: George Feher, original ENDOR report, Physical Review 103 (1956). [^ref-e0a1a853f99f]: ETH Zürich ENDOR technical notes, chapter 8.1. [^ref-8cb304b2393c]: Franke et al., original silicon-donor AED-ENDOR study, Fig. 4 and Results pp. 3–4. [^ref-e9fc93e29db8]: Tyryshkin et al., Davies ENDOR revisited, materials, N@C60 result and relaxation discussion.
Relationships to Other Abstractions¶
Current abstraction Electron–Nuclear Double Resonance Domain-specific
Parents (1) — more general patterns this builds on
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Electron–Nuclear Double Resonance presupposes Resonance Prime
ENDOR requires frequency-selective nuclear and electron resonance responses coupled through the spin system.
Hierarchy paths (10) — routes to 8 parentless roots
- Electron–Nuclear Double Resonance → Resonance → Amplification → Founder Effect → Path Dependence → Dependency
- Electron–Nuclear Double Resonance → Resonance → Feedback
- Electron–Nuclear Double Resonance → Resonance → Temporal Synchronization and Phase Alignment → Coordination → Concurrency
- Electron–Nuclear Double Resonance → Resonance → Temporal Synchronization and Phase Alignment → Coordination → Dependency
- Electron–Nuclear Double Resonance → Resonance → Temporal Synchronization and Phase Alignment → Rhythm → Recurrence
- Electron–Nuclear Double Resonance → Resonance → Amplification → Founder Effect → Path Dependence → Collingridge Dilemma
- Electron–Nuclear Double Resonance → Resonance → Temporal Synchronization and Phase Alignment → Coordination → Task Interdependence → Dependency
- Electron–Nuclear Double Resonance → Resonance → Temporal Synchronization and Phase Alignment → Coordination → Mobilization → Latent Realizable Capacity
- Electron–Nuclear Double Resonance → Resonance → Amplification → Founder Effect → Path Dependence → Time
- Electron–Nuclear Double Resonance → Resonance → Temporal Synchronization and Phase Alignment → Coordination → Task Interdependence → Network → Reservoir-Flux Network → Conservation Laws → Invariance
Neighborhood in Abstraction Space¶
Electron–Nuclear Double Resonance sits in a sparse region of the domain-specific corpus (82nd percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.
Family — Unclustered & Miscellaneous (2551 abstractions)
Nearest neighbors
- Shinnar–Le Roux algorithm — 0.84
- Random-Phase Approximation — 0.83
- Site-directed spin labeling — 0.82
- Magnetic circular dichroism — 0.82
- Spin-exchange — 0.81
Computed from structural-signature embeddings · 2026-10-08