Neutron spectroscopy resolves acoustic and optical phonons in germanium

What changed

B. N. Brockhouse and P. K. Iyengar used neutron spectroscopy to study lattice vibrations in single-crystal germanium. A later participant lecture depicts acoustic and optical phonon branches in two crystal symmetry directions and explains that simple force-constant models did not fully reproduce the measured dispersion.

Scientific scope

B. N. Brockhouse and P. K. Iyengar used neutron spectroscopy to study lattice vibrations in single-crystal germanium. A later participant lecture depicts acoustic and optical phonon branches in two crystal symmetry directions and explains that simple force-constant models did not fully reproduce the measured dispersion. The 1957 short paper and the later participant lecture describe related stages of the work. A dispersion figure reproduced in the lecture and the later 1958 analysis must not be attributed solely to the original short publication. The 1959 erratum is associated with the later analysis. The aluminium experiment with Stewart is a distinct contribution.

Evidence

The linked original works support the scoped statement and contribution attribution. WRS has not independently replayed experiments or reconstructed a full mathematical proof. The 1957 short paper and the later participant lecture describe related stages of the work. A dispersion figure reproduced in the lecture and the later 1958 analysis must not be attributed solely to the original short publication. The 1959 erratum is associated with the later analysis. The aluminium experiment with Stewart is a distinct contribution.

Contributors

• The named authors in the research record · SCIENCE: These are the listed authors of the cited contribution sources. Paper authorship does not quantify individual effort. An incomplete list is explicitly marked; same names are not automatically merged.

• Slow neutron spectroscopy and the grand atlas of the physical world
• Normal Vibrations of Germanium by Neutron Spectrometry

Provisional WRS assessment, edition 2026-10-28.1. Independent expert calibration is pending. This grade does not certify correctness or assign ownership.

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