title: High-flux hard X-ray microbeam using a single-bounce capillary with doubly focused undulator beam.
abstract: 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 x 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 x 10(12) photons s(-1)) and smaller spot sizes (< or =10 microm FWHM in both directions) for a photon flux density of 4.2 x 10(10) photons s(-1) microm(-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.
authors.affiliation: The Biophysics Collaborative Access Team (BioCAT), CSRRI and Department of Biological, Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA. rbarrea@gmail.com
authors.forename: Raul A
authors.initials: RA
authors.lastname: Barrea
authors.forename: Rong
authors.initials: R
authors.lastname: Huang
authors.forename: Sterling
authors.initials: S
authors.lastname: Cornaby
authors.forename: Donald H
authors.initials: DH
authors.lastname: Bilderback
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Irving
mesh_terms: D003300:Copper / Q000032:analysis; D006801:Humans; D007501:Iron / Q000032:analysis; D008297:Male; D011467:Prostate / Q000737:chemistry / Q000473:pathology; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000473:pathology; D017356:Synchrotrons / Q000295:instrumentation; D014965:X-Rays; D015032:Zinc / Q000032:analysis
chemical_list: D003300:Copper; D007501:Iron; D015032:Zinc