Stig Rolandson - Academia.edu (original) (raw)
Papers by Stig Rolandson
Acta Crystallographica Section A, 1974
The neutron diffraction pattern of powdered KC1 has been measured using the triple-axis spectrome... more The neutron diffraction pattern of powdered KC1 has been measured using the triple-axis spectrometer both in the double-axis and the triple-axis modes. The thermal diffuse scattering (TDS) correction, which is very important in the double-axis pattern, is essentially eliminated in the triple-axis mode. Theoretical calculations are presented which give the relative TDS correction for the two cases by calculating the energy distribution of TDS. The Debye-Waller coefficient B using the triple-axis data is found to be (2.17 + 0" 16 A2), which is in agreement with the TDS-corrected values of other workers.
Physical Review B, 1971
The phonon dispersion curves of cesium bromide have been observed by inelastic neutron scattering... more The phonon dispersion curves of cesium bromide have been observed by inelastic neutron scattering in the symmetry directions Delta, Sigma, and Lambda and along the symmetry line T. The measurements were performed at 80 and 300 K using a three-axis crystal spectrometer. The observations have been fitted to various versions of the shell model, and the frequency distribution and the temperature dependence of the Debye temperature have been calculated from the model which gives the best fit to the experimental frequencies.
Solid State Communications, 1969
Abstract Phonon frequencies in KC1 and RbC1 have been determined by neutron scattering. The resul... more Abstract Phonon frequencies in KC1 and RbC1 have been determined by neutron scattering. The results are used to interpret the second-order Raman spectra in these solids. Assignments of two-phonon processes to the reported Raman peaks are made. It is found that most of these peaks can be accounted for.
Physica Status Solidi (b), 1972
The phonon dispersion relations in cesium fluoride have been measured by inelastic neutron scatte... more The phonon dispersion relations in cesium fluoride have been measured by inelastic neutron scattering in the symmetry directions Δ Σ, and A. The measurements were performed at 80 and 300 K using a three-axis spectrometer. The experimental results are compared with theoretical calculations based on various models of the interionic interactions in alkali halides. A satisfactory fit was obtained by a seven-parameter model with only the cesium ion polarizable, and the fit was only slightly improved by using more complicated models with a larger number of adjustable parameters. The frequency distribution has been calculated using an eleven-parameter shell model with both ions polarizable, and compared with similar calculations based on data from macroscopic measurements. Die Phononendispsion in Casiumfluorid wurde durch inelastische Neutronenstreuung in den Symmetrierichtungen Δ, Σ und A gemessen. Die Messungen wurden mit einem dreiachsigen Spektrometer bei 80 und 300 K durchgefuhrt. Die Mesresultate werden mit theoretischen Berechnungen verglichen, denen verschiedene Ionenwechselwirkungsmodelle in Alkalihalogeniden zugrunde liegen. Es wurde zufriedenstellende Ubereinstimmung mit einem Sieben-Parameter-Modell gefunden, in welchem nur das Casium-Ion als polarisierbar angenommen wurde. Kompliziertere Modelle konnten die Ubereinstimmung nur wenig verbessern. Fur die Berechnung der Frequenzverteilung wurde ein Elf-Parameter-Schalen-modell verwendet, in dem die Polarisierbarkeit beider Ionen berucksichtigt wurde. Die Ergebnisse werden mit ahnlichen Berechnungen verglichen, die sich auf Daten makroskopischer Messungen stutzen.
physica status solidi (b), 1970
Phonon dispersion relations in RbI have been obtained by inelastic scattering of thermal neutrons... more Phonon dispersion relations in RbI have been obtained by inelastic scattering of thermal neutrons. Measurements were performed in the crystallographic symmetry directions Δ, Σ, A, and Z at 80 °K and some selected zone boundary phonons were also measured at 300 °K. A simplified version of the generalized shell model, involving a variable number of parameters was fitted to the experimental dispersion curves. From an eleven parameter model the frequency spectrum, the Debye temperature and other physical quantities have been calculated.
Journal of Polymer Science: Polymer Letters Edition, 1974
Journal of Physics C: Solid State Physics
Physical Review B
The Kohn effect in copper has been investigated at 80 K for selected regions of the phonon disper... more The Kohn effect in copper has been investigated at 80 K for selected regions of the phonon dispersion curves, where the effect was believed to be relatively strong, and where good instrumental resolution is obtainable for the neutron spectrometer used. Kohn anomalies are weak in copper, but they can be observed if the measurements are made with due care. About twenty anomalies have been studied and analyzed with the aid of an eighth-nearest-neighbor Born-von Kirmin model. The anomalies are interpreted in terms of points on the Fermi surface in the (100) and (110) planes. The representation picture of the Fermi surface thus obtained is in good agreement with those derived from the Haas-van Alphen and magnetoacoustical measurements.
Phys Rev B, 1972
In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in Na... more In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in NaCl, KCl, RbCl, and RbF have been reported. We now present calculations on these halides using the extended-shell-model approach with both ions polarizable and including next-nearest-neighbor interactions. The parameters obtained in a least-squares fit to the experimental points in the symmetry directions have been used to calculate the phonon frequencies in 512000 equally spaced points in an octant of the Brillouin zone, whereby, after sorting these into intervals of width Deltaomega=2×1011 rad sec-1, the frequency spectrum was obtained. From these spectra the variation of the Debye temperature with temperature was also calculated. The agreement with results from specific-heat measurements for NaCl and KCl is quite satisfactory at low temperatures.
Journal of Physics C: Solid State Physics, 1971
Physical Review B, Sep 14, 1970
In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in Na... more In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in NaCl, KCl, RbCl, and RbF have been reported. We now present calculations on these halides using the extended-shell-model approach with both ions polarizable and including next-nearest-neighbor interactions. The parameters obtained in a least-squares fit to the experimental points in the symmetry directions have been used to calculate the phonon frequencies in 512000 equally spaced points in an octant of the Brillouin zone, whereby, after sorting these into intervals of width Deltaomega=2×1011 rad sec-1, the frequency spectrum was obtained. From these spectra the variation of the Debye temperature with temperature was also calculated. The agreement with results from specific-heat measurements for NaCl and KCl is quite satisfactory at low temperatures.
Acta Crystallographica Section A, 1974
The neutron diffraction pattern of powdered KC1 has been measured using the triple-axis spectrome... more The neutron diffraction pattern of powdered KC1 has been measured using the triple-axis spectrometer both in the double-axis and the triple-axis modes. The thermal diffuse scattering (TDS) correction, which is very important in the double-axis pattern, is essentially eliminated in the triple-axis mode. Theoretical calculations are presented which give the relative TDS correction for the two cases by calculating the energy distribution of TDS. The Debye-Waller coefficient B using the triple-axis data is found to be (2.17 + 0" 16 A2), which is in agreement with the TDS-corrected values of other workers.
Physical Review B, 1971
The phonon dispersion curves of cesium bromide have been observed by inelastic neutron scattering... more The phonon dispersion curves of cesium bromide have been observed by inelastic neutron scattering in the symmetry directions Delta, Sigma, and Lambda and along the symmetry line T. The measurements were performed at 80 and 300 K using a three-axis crystal spectrometer. The observations have been fitted to various versions of the shell model, and the frequency distribution and the temperature dependence of the Debye temperature have been calculated from the model which gives the best fit to the experimental frequencies.
Solid State Communications, 1969
Abstract Phonon frequencies in KC1 and RbC1 have been determined by neutron scattering. The resul... more Abstract Phonon frequencies in KC1 and RbC1 have been determined by neutron scattering. The results are used to interpret the second-order Raman spectra in these solids. Assignments of two-phonon processes to the reported Raman peaks are made. It is found that most of these peaks can be accounted for.
Physica Status Solidi (b), 1972
The phonon dispersion relations in cesium fluoride have been measured by inelastic neutron scatte... more The phonon dispersion relations in cesium fluoride have been measured by inelastic neutron scattering in the symmetry directions Δ Σ, and A. The measurements were performed at 80 and 300 K using a three-axis spectrometer. The experimental results are compared with theoretical calculations based on various models of the interionic interactions in alkali halides. A satisfactory fit was obtained by a seven-parameter model with only the cesium ion polarizable, and the fit was only slightly improved by using more complicated models with a larger number of adjustable parameters. The frequency distribution has been calculated using an eleven-parameter shell model with both ions polarizable, and compared with similar calculations based on data from macroscopic measurements. Die Phononendispsion in Casiumfluorid wurde durch inelastische Neutronenstreuung in den Symmetrierichtungen Δ, Σ und A gemessen. Die Messungen wurden mit einem dreiachsigen Spektrometer bei 80 und 300 K durchgefuhrt. Die Mesresultate werden mit theoretischen Berechnungen verglichen, denen verschiedene Ionenwechselwirkungsmodelle in Alkalihalogeniden zugrunde liegen. Es wurde zufriedenstellende Ubereinstimmung mit einem Sieben-Parameter-Modell gefunden, in welchem nur das Casium-Ion als polarisierbar angenommen wurde. Kompliziertere Modelle konnten die Ubereinstimmung nur wenig verbessern. Fur die Berechnung der Frequenzverteilung wurde ein Elf-Parameter-Schalen-modell verwendet, in dem die Polarisierbarkeit beider Ionen berucksichtigt wurde. Die Ergebnisse werden mit ahnlichen Berechnungen verglichen, die sich auf Daten makroskopischer Messungen stutzen.
physica status solidi (b), 1970
Phonon dispersion relations in RbI have been obtained by inelastic scattering of thermal neutrons... more Phonon dispersion relations in RbI have been obtained by inelastic scattering of thermal neutrons. Measurements were performed in the crystallographic symmetry directions Δ, Σ, A, and Z at 80 °K and some selected zone boundary phonons were also measured at 300 °K. A simplified version of the generalized shell model, involving a variable number of parameters was fitted to the experimental dispersion curves. From an eleven parameter model the frequency spectrum, the Debye temperature and other physical quantities have been calculated.
Journal of Polymer Science: Polymer Letters Edition, 1974
Journal of Physics C: Solid State Physics
Physical Review B
The Kohn effect in copper has been investigated at 80 K for selected regions of the phonon disper... more The Kohn effect in copper has been investigated at 80 K for selected regions of the phonon dispersion curves, where the effect was believed to be relatively strong, and where good instrumental resolution is obtainable for the neutron spectrometer used. Kohn anomalies are weak in copper, but they can be observed if the measurements are made with due care. About twenty anomalies have been studied and analyzed with the aid of an eighth-nearest-neighbor Born-von Kirmin model. The anomalies are interpreted in terms of points on the Fermi surface in the (100) and (110) planes. The representation picture of the Fermi surface thus obtained is in good agreement with those derived from the Haas-van Alphen and magnetoacoustical measurements.
Phys Rev B, 1972
In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in Na... more In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in NaCl, KCl, RbCl, and RbF have been reported. We now present calculations on these halides using the extended-shell-model approach with both ions polarizable and including next-nearest-neighbor interactions. The parameters obtained in a least-squares fit to the experimental points in the symmetry directions have been used to calculate the phonon frequencies in 512000 equally spaced points in an octant of the Brillouin zone, whereby, after sorting these into intervals of width Deltaomega=2×1011 rad sec-1, the frequency spectrum was obtained. From these spectra the variation of the Debye temperature with temperature was also calculated. The agreement with results from specific-heat measurements for NaCl and KCl is quite satisfactory at low temperatures.
Journal of Physics C: Solid State Physics, 1971
Physical Review B, Sep 14, 1970
In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in Na... more In a series of earlier papers, experimental results on phonon dispersion relations at 80 °K in NaCl, KCl, RbCl, and RbF have been reported. We now present calculations on these halides using the extended-shell-model approach with both ions polarizable and including next-nearest-neighbor interactions. The parameters obtained in a least-squares fit to the experimental points in the symmetry directions have been used to calculate the phonon frequencies in 512000 equally spaced points in an octant of the Brillouin zone, whereby, after sorting these into intervals of width Deltaomega=2×1011 rad sec-1, the frequency spectrum was obtained. From these spectra the variation of the Debye temperature with temperature was also calculated. The agreement with results from specific-heat measurements for NaCl and KCl is quite satisfactory at low temperatures.