Open AccessHigh‐flux hard X‐ray microbeam using a single‐bounce capillary with doubly focused undulator beam
Author(s) -
Barrea Raul A.,
Huang Rong,
Cornaby Sterling,
Bilderback Donald H.,
Irving Thomas C.
Publication year - 2009
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049508039782
Subject(s) - beamline , microbeam , undulator , optics , beam (structure) , monochromator , synchrotron , physics , photon , advanced photon source , bremsstrahlung , wavelength
A pre‐focused X‐ray beam at 12 keV and 9 keV has been used to illuminate a single‐bounce capillary in order to generate a high‐flux X‐ray microbeam. The BioCAT undulator X‐ray beamline 18ID at the Advanced Photon Source was used to generate the pre‐focused beam containing 1.2 × 10 13 photons s −1 using a sagittal‐focusing double‐crystal monochromator and a bimorph mirror. The capillary entrance was aligned with the focal point of the pre‐focused beam in order to accept the full flux of the undulator beam. Two alignment configurations were tested: (i) where the center of the capillary was aligned with the pre‐focused beam (`in‐line') and (ii) where one side of the capillary was aligned with the beam (`off‐line'). The latter arrangement delivered more flux (3.3 × 10 12 photons s −1 ) and smaller spot sizes (≤10 µm FWHM in both directions) for a photon flux density of 4.2 × 10 10 photons s −1 µm −2 . The combination of the beamline main optics with a large‐working‐distance (approximately 24 mm) capillary used in this experiment makes it suitable for many microprobe fluorescence applications that require a micrometer‐size X‐ray beam and high flux density. These features are advantageous for biological samples, where typical metal concentrations are in the range of a few ng cm −2 . Micro‐XANES experiments are also feasible using this combined optical arrangement.