Where are Protons and Deuterons in KH_pD_{1-p}CO_3? A Neutron Diffraction Study

TL;DR

This neutron diffraction study reveals the specific locations of protons and deuterons in mixed KH_{p}D_{1-p}CO_3 crystals, showing they are not randomly distributed but form ordered macroscopic quantum states.

Contribution

The paper provides the first detailed neutron diffraction analysis of proton and deuteron positions in mixed KH_{p}D_{1-p}CO_3 crystals, demonstrating non-random distribution and macroscopic quantum behavior.

Findings

Protons and deuterons are not randomly distributed in the crystal.

The space group symmetry remains consistent across compositions.

Crystals exhibit macroscopic quantum states.

Abstract

The crystals of potassium hydrogen carbonate (KHCO3) and the KDCO3 analogue are isomorphous. They are composed of hydrogen or deuterium bonded centrosymmetric dimers (HCO3-)(2) or (DCO3-)(2). The space group symmetry of KHpD1-pCO3 (p approximate to 0.75) determined with neutron diffraction is identical to those of KHCO3 and KDCO3. This is at variance with a random distribution of H and D nuclei. These crystals are macroscopic quantum systems in which protons or/and deuterons merge into macroscopic states.