U.S. Geological Survey, Procurement and Contracts Section, Building 25, Box 25046, MS 204A, Denver Federal Center, Denver, CO 80225

W -- LEASE WITH OPTION TO PURCHASE X-RAY MICROFLUORESCENCE SPECTROMETER SOL 5-6059 POC John J. Arnold, Contracting Officer, (303) 236-5900 x349, Mickey Lechuga, Contract Specialist, (303) 236-5900 x 332 The USGS has a requirement to lease with the option to purchase one (1) Kevex Omicron x-ray microfluorescence spectrometer (model 952-1) to perform trace and phase analysis in geologic materials. This unit has the ability to do automatic line and area elemental scans to determine elemental distributions in minerals. The x-ray microfluorescence system shall provide the elemental sensitivity of bulk XRF spectroscopy along with the spatial resolution approaching scanning electron microscopy and energy dispersive XRF spectroscopy (SEM/EDS). The Kevex Omicron system (brand name or equal) has the following salient characteristics: The elemental sensitivity of the x-ray system shall exceed that of a SEM/EDS by approximately a factor of 100; The sample preparation required shall be minimal - no coating required; The x-ray system shall have the sensitivity required for small area (50 to 200 ~m diameter analyses; The x-ray system shall have a precision XYZ microstepping stage and a camera viewing system to locate and analyze small features of interest; The x-ray system shall be able to analyze elements Na (atomic number = 11) through U (atomic number = 92) simultaneously; The sample chamber shall accommodate a wide range of sample types, including standard x-ray cups, thin sections, and irregular rock slabs up to 8 inches across; The high-flux density microfocus x-ray tube will use a Rh target and operate at energies of 4 to 50 kV; a computer-controllable filter/collimator turret will be provided and collimators of 50 ~m, 100 ~m, and 2000 ~m shall be included; and the x-ray system will be an energy-dispersive type using a multichannel analyzer - its resolution shall be 175 eV FWHM (full width at half maximum) at 5.9 keV (1000 cps). The due date for submission is on or about 45 days after this notice is published. Delivery shall be F.O.B. Destination Denver, CO within 120 days after contract award. All responsible sources may submit an offer which will be considered. (0121)

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