M. Krzystyniak

Anomalous neutron Compton scattering cross sections in ammonium hexachlorometallates

The authors have performed neutron Compton scattering measurements on ammonium hexachloropalladate (NH(4))(2)PdCl(6) and ammonium hexachlorotellurate (NH(4))(2)TeCl(6). Both substances belong to the family of ammonium metallates. The aim of the experiment was to investigate the possible role of electronic environment of a proton on the anomaly of the neutron scattering intensity. The quantity of interest that was subject to experimental test was the reduction factor of the neutron scattering intensities. In both samples, the reduction factor was found to be smaller than unity, thus indicating the anomalous neutron Compton scattering from protons. Interestingly, the anomaly decreases with decreasing scattering angle and disappears at the lowest scattering angle (longest scattering time). The dependence of the amount of the anomaly on the scattering angle (scattering time) is the same in both substances (within experimental error). Also, the measured widths of proton momentum distributions are equal in both metallates. This is consistent with the fact that the attosecond proton dynamics of ammonium cations is fairly well decoupled from the dynamics of the sublattice of the octahedral anions PdCl(6) (2-) and TeCl(6) (2-), respectively. The hypothesis is put forward that proton-electron decoherence processes are responsible for the considered effect. Decoherence processes may have to do rather with the direct electronic environment of ammonium protons and not with the electronic structure of the metal-chlorine bond.

Neutron Compton scattering from the super proton conductor H3OSbTeO6 and polyethylene: a comparison of proton momentum distributions and reduced cross-sections

Neutron Compton scattering (NCS) results at large momentum transfers (q?60?130???1) obtained from the super proton conductor H3OSbTeO6 (powder at T = 295?K) are compared with those obtained from polyethylene (PE, foil at T = 295?K). The Compton profiles of protons in both systems are approximately Gaussians with equal widths, ?H?5???1, within experimental error, thus indicating that the effective (averaged over all spatial directions) Born?Oppenheimer (BO) potentials of protons in both systems are similar. In contrast, the anomalous decrease of scattering intensity from H in H3OSbTeO6 is only about 50% of that observed in PE. In a proposed theoretical frame (based on the violation of the BO approximation and attosecond proton?electron quantum entanglement) these comparative results reveal that the more mobile protons of the proton conductor are subject to a significantly faster decoherent quantum dynamics, which naturally causes a reduction of the anomaly in the scattering intensity. These new results may contribute to testing the validity of competing theoretical models. Connection with related NCS results from the super proton conductor Rb3H(SO4)2 is briefly made.

A new data treatment scheme for integrated intensities in neutron Compton scattering

A new data reduction scheme is presented for time-of-flight data collected in neutron Compton scattering experiments with the aim of obtaining the scattering intensities. The method proposed is a single number approach as it makes use of the count rates detected in the individual time-of-flight channels. The most convenient seems to be the variant of the method where time-of-flight channels are chosen corresponding to centers of recoil peaks of individual masses. With such a choice of time-of-flight channels, the method presented is more robust against unwanted background signals and noise than the method widely used in NCS studies based on fitting entire time-of-flight band shapes in the framework of the convolution approximation. Moreover, it should perform better than the model-free Dorner method as it does not require the numerical integration of the signal, which is also sensitive to baseline and noise. As an example of the performance of the new method, polyethylene data are treated and compared to results obtained previously using conventional data reduction and the model-free method proposed by Dorner. It is shown that all three data reduction schemes lead to the same results for the scattering intensities of protons in polyethylene, thus strengthening the conclusion about the anomalous scattering cross-section of protons in this substance. In the future the new data reduction scheme can be used to treat the data from other experiments where the conventional NCS data treatment and/or Dorner method fail due to noise and/or unwanted background signals present in the time-of-flight spectra.

Quantum Entanglement and Decoherence Due to Coupling of Protons to Electronic Environment

In recent years many scattering experiments have been performed on hydrogen containing materials which showed a scattering behavior different from the expectation according to standard theories. These scattering anomalies are attributed to the existence of short lived protonic quantum entanglement (QE) and decoherence. It was suggested that also electronic degrees of freedom might be involved in the anomalous scattering behavior. Here, the influence of the electronic structure surrounding the H atoms in different materials on the neutron scattering cross section of hydrogen is investigated. Experimental neutron Compton scattering results of H2O / D2O mixtures and LiH at different temperatures are presented. Also LaH2 which exhibits metallic properties and LaH3 which is an insulator — i.e., both materials have different electronic structures — are investigated at room temperature. It is found that different electronic environments lead to different scattering behavior, thus strongly supporting the supposition that the electronic degrees of freedom are engaged in the protonic attosecond QE and the decoherence process. Furthermore, we present very recent results of experimental tests of the data analysis procedure which have been criticized recently. We show that the data analysis procedure is correct and criticisms are irrelevant for the experimental setup used in our NCS experiments.