The Experts below are selected from a list of 431949 Experts worldwide ranked by ideXlab platform
S D Conradson - One of the best experts on this subject based on the ideXlab platform.
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pair distribution function and structure factor of spherical particles
Physical Review B, 2006Co-Authors: Rafael C Howell, Thomas Proffen, S D ConradsonAbstract:The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an Experimental Sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed.
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Pair distribution function and structure factor of spherical particles
Physical Review B, 2006Co-Authors: Rafael C Howell, Thomas Proffen, S D ConradsonAbstract:The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an Experimental Sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed.Comment: 7 pages, 6 figure
Rafael C Howell - One of the best experts on this subject based on the ideXlab platform.
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pair distribution function and structure factor of spherical particles
Physical Review B, 2006Co-Authors: Rafael C Howell, Thomas Proffen, S D ConradsonAbstract:The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an Experimental Sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed.
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Pair distribution function and structure factor of spherical particles
Physical Review B, 2006Co-Authors: Rafael C Howell, Thomas Proffen, S D ConradsonAbstract:The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an Experimental Sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed.Comment: 7 pages, 6 figure
Thomas Proffen - One of the best experts on this subject based on the ideXlab platform.
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pair distribution function and structure factor of spherical particles
Physical Review B, 2006Co-Authors: Rafael C Howell, Thomas Proffen, S D ConradsonAbstract:The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an Experimental Sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed.
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Pair distribution function and structure factor of spherical particles
Physical Review B, 2006Co-Authors: Rafael C Howell, Thomas Proffen, S D ConradsonAbstract:The availability of neutron spallation-source instruments that provide total scattering powder diffraction has led to an increased application of real-space structure analysis using the pair distribution function. Currently, the analytical treatment of finite size effects within pair distribution refinement procedures is limited. To that end, an envelope function is derived which transforms the pair distribution function of an infinite solid into that of a spherical particle with the same crystal structure. Distributions of particle sizes are then considered, and the associated envelope function is used to predict the particle size distribution of an Experimental Sample of gold nanoparticles from its pair distribution function alone. Finally, complementing the wealth of existing diffraction analysis, the peak broadening for the structure factor of spherical particles, expressed as a convolution derived from the envelope functions, is calculated exactly for all particle size distributions considered, and peak maxima, offsets, and asymmetries are discussed.Comment: 7 pages, 6 figure
S R Bakalyar - One of the best experts on this subject based on the ideXlab platform.
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Performance of Experimental Sample injectors for high-performance liquid chromatography microcolumns.
Journal of chromatography. A, 2000Co-Authors: M D Foster, M A Arnold, J A Nichols, S R BakalyarAbstract:An Experimental injector for HPLC microcolumns and a 3-nl conductivity detector connected directly to the injector outlet with a 19-nl tube were used to study injector dispersion, guide the design of improved injectors, and suggest appropriate injection techniques. With regard to the small injection volumes required when no on-column concentration technique is used, we show that in some circumstances: (i) there are two volumes to be considered, the Sample volume (that which is intended to be injected) and the effective injection volume (that which contains all the Sample after it has completely emerged from the injector). Due to dispersion, the latter is often many times the former. An injector performance factor is defined as the ratio of the two volumes. (ii) A smaller Sample chamber volume in an injector does not necessarily produce a proportionately smaller effective injection volume, in which case there is a reduction of peak height that degrades sensitivity without a commensurate reduction in peak width that would improve resolution. (iii) Adjusting the geometry of the Sample chamber and stator passage can significantly improve injector performance, as illustrated for Sample volumes from 2 nl to 1 microl. (iv) In some cases, reducing the diameter of an injector passageway in an attempt to reduce dispersion actually causes performance to worsen.
M D Foster - One of the best experts on this subject based on the ideXlab platform.
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Performance of Experimental Sample injectors for high-performance liquid chromatography microcolumns.
Journal of chromatography. A, 2000Co-Authors: M D Foster, M A Arnold, J A Nichols, S R BakalyarAbstract:An Experimental injector for HPLC microcolumns and a 3-nl conductivity detector connected directly to the injector outlet with a 19-nl tube were used to study injector dispersion, guide the design of improved injectors, and suggest appropriate injection techniques. With regard to the small injection volumes required when no on-column concentration technique is used, we show that in some circumstances: (i) there are two volumes to be considered, the Sample volume (that which is intended to be injected) and the effective injection volume (that which contains all the Sample after it has completely emerged from the injector). Due to dispersion, the latter is often many times the former. An injector performance factor is defined as the ratio of the two volumes. (ii) A smaller Sample chamber volume in an injector does not necessarily produce a proportionately smaller effective injection volume, in which case there is a reduction of peak height that degrades sensitivity without a commensurate reduction in peak width that would improve resolution. (iii) Adjusting the geometry of the Sample chamber and stator passage can significantly improve injector performance, as illustrated for Sample volumes from 2 nl to 1 microl. (iv) In some cases, reducing the diameter of an injector passageway in an attempt to reduce dispersion actually causes performance to worsen.
