The core measurement toolbox
Water structure is not measured by a single test. The field relies on complementary techniques that each capture different aspects of the hydrogen‑bond network.
X-ray and neutron scattering
These methods capture average structural features such as coordination numbers and radial distribution functions. They are strong for tracking changes with temperature or pressure. They do not directly measure long‑lived “memory” effects without additional evidence.
IR and Raman spectroscopy
Vibrational spectroscopy is sensitive to hydrogen‑bond environments. It is useful for comparing samples under controlled conditions, but interpretation depends on calibration and the specific bands analyzed.
NMR and dielectric measurements
These emphasize dynamics and molecular motion rather than static structure. They can reveal changes in relaxation times and mobility, which are relevant to claims of “ordered” water but must be interpreted carefully.
X-ray absorption and emission
XAS/XES methods probe local electronic structure and hydrogen‑bond arrangements. They are powerful but require modeling assumptions that can shift conclusions if not transparent.
Interpretation guardrails
- Match the claim to a method that directly tests it.
- Distinguish instrument signal changes from mechanistic causation.
- Prefer studies with clear protocols and reproducible instrumentation.
If a claim cannot be evaluated with these tools, it should be labeled as interpretation rather than evidence.