Specs_SEM_1.docx

Technical Specifications

This requisition is to acquire a Scanning Electron Microscope (SEM) and supporting components that together form a system for the analysis of volcanic rock samples. This system is to be installed at the U.S. Geological Survey Alaska Volcano Observatory in Anchorage, AK.

Rapid characterization of the products (ash and rock) of volcanic eruptions is essential for assessing the associated volcanic hazards and determining the likelihood and magnitude of continuing eruptive activity. The system will also be used to support mineral analysis and resource characterization by Alaska Science Center personal, including initiatives such as characterizing the mineralogy of placer sands, mine waste, and other materials.

We seek a field emission (FE) source scanning electron microscopes (SEM) with backscatter electron (BSE), secondary electron (SE), cathodoluminescence (CL), and electron dispersive spectrometry (EDS) detectors to enable imaging and quantitative elemental analysis of geologic materials. The requested SEM system should be able to run under variable pressures, accept a range of sample sizes, and have the latest EDS technology (silicon drift detector, or SDD) for elemental point and mapping analysis.

Minimum required technical specifications for Scanning Electron Microscope (SEM)

· Schottky field Emission (FE) source

· Beam current should achieve a range of 10 pA to 300 nA or better, accelerating voltage should be variable over a range of at least 0.5 to 30 kV

· Beam current measurement system (in-column probe current detector or stage mounted faraday cup, with internal or external picoammeter with reading read to SEM control software)

· SEM must have high vacuum and low vacuum settings

· Motorized eucentric sample stage X, Y, and Z axis, tilt, and rotation; stage automation software

· Removable sample stage holders capable of holding (1) top reference holder with capacity for at least seven 1-inch circular mounts at least 1 cm-thick, (2) top reference holder with capacity for at least two standard petrographic thin sections alongside one 1-inch circular mount at least 1 cm-thick, and (3) stub pin mount (1 cm) holder with capacity for at least 7 pins. SEM must be capable of image and EDS point analysis (beam-centered) on all sample positions

· System supplied with all necessary vacuum pumps, air compressors, and support systems

· No water chiller or liquid nitrogen required for SEM or detector operation

· Detectors including:

· Back-scattered electron (BSE) detector

· Secondary electron (SE) detector

· Cathodoluminescence (CL) panchromatic detector with minimum 185–850 nm spectral range

· Automated image mosaic capabilities (automated stitching of images) over several cm2 area (standard petrographic thin section or 1-inch round)

· Electron dispersive spectrometry (EDS) detectors (see below)

Minimum required technical specifications for EDS system

· Two silicon drift EDS detectors, each with windows at least 100 mm2 in size

· Spectral resolution of at least 127 eV at the Mn Kα peak

· Software (including an additional license for offline use) capable of:

· X-ray mapping and SEM imaging (BSE, SE, and CL) capability, including automated stitching of multiple maps and images over large areas (coverage of standard petrographic thin section or 1-inch round)

· Capability to correct X-ray maps for background and peak overlap

· Quantitative EDS point and rastered area analysis with ability to calibrate to standards

· Automated batch runs of standardized EDS multi-point analyses and image acquisition by controlling SEM x,y,z stage position

· EDS software capable of utilizing input from multiple (2) EDS detectors

· EDS software able to export tabular quantitative data to Excel or .csv files

· Images exported as both 8 bit and 15 bit (or greater) files

· Automated spectra collection from features delineated by particle analysis of BSE grayscale images

· Capability to classify materials via comparison of EDS spectra to user- and(or) vendor-supplied databases

General minimum technical specifications

· All software supplied for the system must be fully licensed to the end-user.

· Any computer hardware supplied with this system must meet DOI specifications. No prohibited hardware will be allowed. A list of acquisition compliant companies will be supplied upon request.

· On-site installation, and training of all system components (SEM and EDS) to be included as part of the system

· Warranty: minimum of 1 year all parts and labor, including site visits

· Vendor must be able to provide a service contract

Highly desired technical specifications

· Sample chamber dimensions with a motorized stage limits reaching at least a 10x10 cm area.

· Larger capacity sample stage holders capable of holding (1) top reference holder with capacity for at least nine 1-inch circular mounts at least 1 cm-thick, (2) top reference holder with capacity for at least four standard petrographic thin sections alongside one 1-inch circular mount at least 1 cm-thick, and (3) stub pin mount (5 mm) holder with capacity for at least 7 pins. SEM must be capable of image and EDS point analysis (beam-centered) on all sample positions.

· Physical instrument should ideally fit into a 2.8 x 2.6 m area, irrespective of instrument access requirements (not including computer monitors)

· Optical imaging system to cover full sample holder area and automatically provide referenced image to SEM navigation system.

· Preferred CL detector: Deben Centaurus with parabolic mirror or equivalent

· Preferred EDS system: Oxford Ultim Max EDS with AztecLive Advanced and AztecFeature add-on control software (which will also enhance interoperability with other USGS volcano observatories and Mineral Resources Program labs, who also use AztecLive software). Computer upgrade to handle higher processing needs (≥5 GHz speed) of AztecFeature and large area mapping.

· Two-day Oxford specific on-site user training.