advanced fe-sem : from nano-imaging to chemical and structural analyses

Advanced FE-SEM:

from Nano-imaging to Chemical and Structural Analyses

Chi MaDivision Analytical Facility

Division of Geological and Planetary Sciences, Caltechchi@gps.caltech.edu

http://www.gps.caltech.edu/facilities/analytical/

CSEM 2003

A high-resolution analytical scanning electron microscope (LEO 1550VP) was installed in Sept 2002 at Caltech GPS Division Analytical Facility and became

available for campus-wide use in Dec 2002.

The new PC-based LEO 1550 SEM is a multipurpose state-of-the-art instrument capable of SE, BSE, variable pressure SE, CL imaging, high-resolution imaging (down to 1 nm), chemical and crystallographic analyses. This is a field emission SEM which can operate at voltages ranging from 200 V to 30 kV and at magnifications ranging from 20 x to 900 kx for a wide variety of applications.  The 1550 is equipped with two state-of-the-art accessories.  The first, an Oxford energy-dispersive X-ray spectrometer (EDS), can determine and map the elemental distribution within a region or along a line, or perform a quantitative chemical analysis of a point or region.  The other accessory, a HKL electron backscatter diffraction system (EBSD), can determine the crystal structure and orientation of the sample at a specific point, and conduct orientation mapping and phase identification at submicron scale.

The SEM was acquired and is supported in part by the MRSEC program of the NSF under DMR-0080065.

CSEM 2003

The analytical SEM is having a wonderful impact on campus.

Since Dec 2002, about 85 users from 40 faculty research groups on campus and JPL have used the SEM. They are from:

CSEM 2004

Material SciencesEE, ME, CSApplied PhysicsAero-engineeringBio-engineering

BiologyChemistryChemical EngineeringPhysics

GeologyGeochemistryGeophysicsGeobiology

Imaging Capabilities (5 electron detectors)

• High resolution Imaging – In-Lens SE1

• Low Voltage Imaging (200V – 5kV) – better surface imaging due to reduced beam penetration

• Compositional Contrast Imaging - BSE

• Orientation Contrast Imaging – FSE

• Variable Pressure SE Imaging (3Pa-100Pa)

• Cathodoluminescence Imaging• STEM imaging

CSEM 2003

Chemical Analysis - EDS• Detector capable of detecting Be to U• Quantitative EDS analysis -

Quantitative results with a relative accuracy of better than 5% and detection limits of better than 0.5% can be readily obtained.

• X-ray mapping

Structural Analysis - EBSD

• Orientation mapping – texture analysis

• Phase IDCSEM 2003

Imaging, EDS and EBSD analyses at same time

CSEM 2003

BSE image showing chemical variation of micas

CL image of benitoite

STEM (left) and SE (right) images of borosilicate fibers