This work reports a harmonic-rejection scheme based on the combination of Si(111) monochromator a... more This work reports a harmonic-rejection scheme based on the combination of Si(111) monochromator and Si(220) harmonic-rejection crystal optics. This approach is of importance to a wide range of X-ray applications in all three major branches of modern X-ray science (scattering, spectroscopy, imaging) based at major facilities, and especially relevant to the capabilities offered by the new diffraction-limited storage rings. It was demonstrated both theoretically and experimentally that, when used with a synchrotron undulator source over a broad range of X-ray energies of interest, the harmonic-rejection crystals transmit the incident harmonic X-rays on the order of 10. Considering the flux ratio of fundamental and harmonic X-rays in the incident beam, this scheme achieves a total flux ratio of harmonic radiation to fundamental radiation on the order of 10. The spatial coherence of the undulator beam is preserved in the transmitted fundamental radiation while the harmonic radiation is s...
An advanced ultra-small-angle X-ray scattering (USAXS) instrument, using the Bonse-Hart design an... more An advanced ultra-small-angle X-ray scattering (USAXS) instrument, using the Bonse-Hart design and installed at APS, is a robust and reliable instrument, providing a scattering vector (q) range of nearly 4 decades (0.00015 to 1 Å-1), an intensity dynamic range of up to 9 decades, standard-less absolute intensity calibration, and USAXS imaging capabilities. This type of instrument typically uses channel-cut crystals
The UNICAT collaboration at the APS has constructed an insertion device beamline facility to supp... more The UNICAT collaboration at the APS has constructed an insertion device beamline facility to support fundamental research in advanced materials and condensed matter physics. The primary research techniques used by UNICAT members include structural crystallography, diffuse x-ray scattering, magnetic x-ray scattering, ultra-small-angle x-ray scattering, micro-beam scattering, inelastic x-ray scattering and spectroscopy, surface and interface scattering, coherent x-ray diffraction, and time-resolved
ABSTRACT It is a well-documented challenge to quantify the dynamic behaviors of concentrated, opt... more ABSTRACT It is a well-documented challenge to quantify the dynamic behaviors of concentrated, optically opaque micrometer-sized colloidal suspensions with laser scattering techniques due to the complications introduced by multiple scattering events. In order to overcome this limit, we have developed an ultra-small angle X-ray scattering (USAXS) based X-ray photon correlation spectroscopy (XPCS) technique to probe the equilibrium dynamics of such materials. With this technique as well as USAXS, we have tracked the structural and dynamical properties of concentrated monodisperse suspensions of different sized polystyrene (PS) microspheres in glycerol. For these PS suspensions, we found their static structures display a hard-sphere like behavior. Furthermore, by analyzing the intensity autocorrelation functions, we found the inverse of the effective diffusion coefficients display a peak with respect to the scattering vector that resembles the peaks in the static structure factors, a signature of de-Gennes narrowing. We also identified evidence supporting a collective motion of the microspheres.
... A good review of EXAFS can be found in Teo and Joy (1981) which gives detailed descriptions o... more ... A good review of EXAFS can be found in Teo and Joy (1981) which gives detailed descriptions of the physics of the technique. ... 137-155, Electrochem. Sot., Pennington, NJ. Teo, BK and Joy, DC, Eds., (1981). EXAFS S~ec~roscopy, Plenum, New York. References. ...
This work reports a harmonic-rejection scheme based on the combination of Si(111) monochromator a... more This work reports a harmonic-rejection scheme based on the combination of Si(111) monochromator and Si(220) harmonic-rejection crystal optics. This approach is of importance to a wide range of X-ray applications in all three major branches of modern X-ray science (scattering, spectroscopy, imaging) based at major facilities, and especially relevant to the capabilities offered by the new diffraction-limited storage rings. It was demonstrated both theoretically and experimentally that, when used with a synchrotron undulator source over a broad range of X-ray energies of interest, the harmonic-rejection crystals transmit the incident harmonic X-rays on the order of 10. Considering the flux ratio of fundamental and harmonic X-rays in the incident beam, this scheme achieves a total flux ratio of harmonic radiation to fundamental radiation on the order of 10. The spatial coherence of the undulator beam is preserved in the transmitted fundamental radiation while the harmonic radiation is s...
An advanced ultra-small-angle X-ray scattering (USAXS) instrument, using the Bonse-Hart design an... more An advanced ultra-small-angle X-ray scattering (USAXS) instrument, using the Bonse-Hart design and installed at APS, is a robust and reliable instrument, providing a scattering vector (q) range of nearly 4 decades (0.00015 to 1 Å-1), an intensity dynamic range of up to 9 decades, standard-less absolute intensity calibration, and USAXS imaging capabilities. This type of instrument typically uses channel-cut crystals
The UNICAT collaboration at the APS has constructed an insertion device beamline facility to supp... more The UNICAT collaboration at the APS has constructed an insertion device beamline facility to support fundamental research in advanced materials and condensed matter physics. The primary research techniques used by UNICAT members include structural crystallography, diffuse x-ray scattering, magnetic x-ray scattering, ultra-small-angle x-ray scattering, micro-beam scattering, inelastic x-ray scattering and spectroscopy, surface and interface scattering, coherent x-ray diffraction, and time-resolved
ABSTRACT It is a well-documented challenge to quantify the dynamic behaviors of concentrated, opt... more ABSTRACT It is a well-documented challenge to quantify the dynamic behaviors of concentrated, optically opaque micrometer-sized colloidal suspensions with laser scattering techniques due to the complications introduced by multiple scattering events. In order to overcome this limit, we have developed an ultra-small angle X-ray scattering (USAXS) based X-ray photon correlation spectroscopy (XPCS) technique to probe the equilibrium dynamics of such materials. With this technique as well as USAXS, we have tracked the structural and dynamical properties of concentrated monodisperse suspensions of different sized polystyrene (PS) microspheres in glycerol. For these PS suspensions, we found their static structures display a hard-sphere like behavior. Furthermore, by analyzing the intensity autocorrelation functions, we found the inverse of the effective diffusion coefficients display a peak with respect to the scattering vector that resembles the peaks in the static structure factors, a signature of de-Gennes narrowing. We also identified evidence supporting a collective motion of the microspheres.
... A good review of EXAFS can be found in Teo and Joy (1981) which gives detailed descriptions o... more ... A good review of EXAFS can be found in Teo and Joy (1981) which gives detailed descriptions of the physics of the technique. ... 137-155, Electrochem. Sot., Pennington, NJ. Teo, BK and Joy, DC, Eds., (1981). EXAFS S~ec~roscopy, Plenum, New York. References. ...
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Papers by Gabrielle Long