The Advanced Light Source (ALS) beamline (BL) 10.3.2 is an apparatus for X-ray microprobe spectroscopy and diffraction experiments, operating in the energy range 2.4-17 keV. The performance of the beamline, namely the spatial and energy resolutions of the measurements, depends significantly on the collimation quality of light incident on the monochromator. In the BL 10.3.2 end-station, the synchrotron source is imaged 1:1 onto a set of roll slits which form a virtual source. The light from this source is collimated in the vertical direction by a bendable parabolic cylinder mirror. Details are presented of the mirror design, which allows for precision assembly, alignment and shaping of the mirror, as well as for extending of the mirror operating lifetime by a factor of ∼10. Assembly, mirror optimal shaping and preliminary alignment were performed ex situ in the ALS X-ray Optics Laboratory (XROL). Using an original method for optimal ex situ characterization and setting of bendable X-ray optics developed at the XROL, a root-mean-square (RMS) residual surface slope error of 0.31 µrad with respect to the desired parabola, and an RMS residual height error of less than 3 nm were achieved. Once in place at the beamline, deviations from the designed optical geometry (e.g. due to the tolerances for setting the distance to the virtual source, the grazing incidence angle, the transverse position) and/or mirror shape (e.g. due to a heat load deformation) may appear. Due to the errors, on installation the energy spread from the monochromator is typically a few electron-volts. Here, a new technique developed and successfully implemented for at-wavelength (in situ) fine optimal tuning of the mirror, enabling us to reduce the collimation-induced energy spread to ∼0.05 eV, is described.

The crystallographic characterization of framework-guest interactions in metal-organic frameworks allows the location of guest binding sites and provides meaningful information on the nature of these interactions, enabling the correlation of structure with adsorption behavior. Here, techniques developed for in situ single-crystal X-ray diffraction experiments on porous crystals have enabled the direct observation of CO, CH₄, N₂, O₂, Ar, and P₄ adsorption in Co₂(dobdc) (dobdc^4- = 2,5-dioxido-1,4-benzenedicarboxylate), a metal-organic framework bearing coordinatively unsaturated cobalt(ii) sites. All these molecules exhibit such weak interactions with the high-spin cobalt(ii) sites in the framework that no analogous molecular structures exist, demonstrating the utility of metal-organic frameworks as crystalline matrices for the isolation and structural determination of unstable species. Notably, the Co-CH₄ and Co-Ar interactions observed in Co₂(dobdc) represent, to the best of our knowledge, the first single-crystal structure determination of a metal-CH₄ interaction and the first crystallographically characterized metal-Ar interaction. Analysis of low-pressure gas adsorption isotherms confirms that these gases exhibit mainly physisorptive interactions with the cobalt(ii) sites in Co₂(dobdc), with differential enthalpies of adsorption as weak as -17(1) kJ mol^-1 (for Ar). Moreover, the structures of Co₂(dobdc)·3.8N₂, Co₂(dobdc)·5.9O₂, and Co₂(dobdc)·2.0Ar reveal the location of secondary (N₂, O₂, and Ar) and tertiary (O₂) binding sites in Co₂(dobdc), while high-pressure CO₂, CO, CH₄, N₂, and Ar adsorption isotherms show that these binding sites become more relevant at elevated pressures.

The autocollimator and moveable pentaprism based DLTP [NIM A 616 (2010) 212-223], a low-budget, NOM-like profiler at the Advanced Light Source (ALS), has been upgraded to provide fast, highly accurate surface slope metrology for long, side-facing, x-ray optics. This instrument arrangement decreases sensitivity to environmental conditions and removes the gravity effect on mirror shape. We provide design details of an affordable base tool. Including Clean-Rm. Environ. Arrangements in the New ALS X-ray Opt. Lab. with Adv. Temp. Stabilization and Turbulence Reduction, That Yield Measurements in under 8 Hours with Accuracy Better Than 30 Nanoradians for Super Polished, 190 Mm Flat Opt., Ltd. Mainly by Residual Temporal Instability of the Exp. Set-up. the Upgraded DLTP Has Been Calibrated for Highly Curved X-ray Opt., Allowing Same Day Measurements of A 15 M ROC Sphere with Accuracy of Better Than 100 Nanoradians . the Developed Calibration Procedure is Discussed in Detail. We Propose This Specific 15 M ROC Sphere for Use As A Round-robin Calibration Test Optic.