Outside links:
Microbeam Analysis Society
Microscopy Society of America

IAP 2008 Courses

Summer JEOL-WDS Training Program

Remote operation of the electron microprobes

Electron microprobe facility upgrade

Monazite and xenotime geochronology

Remote operation of the electron microprobes

Our JEOL microprobes can be remotely operated through an internet connection using a pcAnywhere client, or a NetOp guest software. These terminal emulation programs enables a remote user to take control of the computer running the microprobe. The user can remotely operate the dQant32 and dPict32 programs. However, tasks like switching between point mode and raster mode, focusing the sample, adjusting the gain and current in the BE detector and changing samples still need manual intervention.

Electron microprobe facility upgrade

We have recently upgraded of our JEOL automation systems. The new system, provided by Geller Microanalytical Lab., is PC-based state-of-the-art, and provides greater flexibility for data reduction, large area scanning electron imaging and quantitative elemental X-ray imaging (elemental mapping) by rastering the beam or the stage, advanced digital image analysis and TIF or JPG-formatted, easily transportable images to other computing environments. The dSspec system automates the microprobes, whereas, the dQant32 and dPict32 programs enable quantitative analysis and digital imaging capabilities.

Stage rastered imaging, pioneered by Frank Spear and David Wark of RPI, Troy, is now integrated in the Geller software. This feature is exceptional for the purpose of large area elemental X-ray imaging.

One of our microprobes now has an LDEC synthetic multilayered diffracting element (2d=98 angstrom) in a WD-spectrometer, optimized for carbon analysis. Boron can also be analyzed with this spectrometer. This is in addition to an exisiting LDE1 multilayer (2d=60 angstrom) used for oxygen analysis. This upgrade makes this microprobe an extremely versatile instrument, capable of analyzing any element from B through U. An LDE1 multilayer is now also available on our second microprobe making it capable of analyzing the light elements F,O,N and C.

We have also upgraded our sample preparation facility with a Covington lap polishing wheel, a Buehler auto-polisher and a Denton DV502A Carbon Coater.

Monazite and xenotime geochronology

We have successfully measured Pb, Th and U and calculated chemical dates in monazites and xenotimes from Mt. Narrayer (Jack Hills, Australia) and the Precambrian granulite-gneiss complexes of northeastern and eastern India, (Shillong-Meghalaya, Chotanagpur and Eastern Ghats).

Publications:

• Chatterjee, N., Crowley, J.L., Mukherjee, A. and Das, S. (2008) Geochronology of the 983 Ma Chilka Lake Anorthosite, Eastern Ghats Belt, India: implications for pre-Gondwana tectonics. Journal of Geology, 116, 105-118.doi: 10.1086/528901
• Chatterjee, N., Crowley, J.L. and Ghose, N.C. (2008) Geochronology of the 1.55 Ga Bengal anorthosite and Grenvillian metamorphism in the Chotanagpur gneissic complex, eastern India. Precambrian Research, 161, 303-316.doi:10.1016/j.precamres.2007.09.005
• Chatterjee, N., Mazumdar, A.C., Bhattacharya, A. and Saikia, R.R. (2007) Mesoproterozoic granulites of the Shillong-Meghalaya Plateau: Evidence of westward continuation of the Prydz Bay Pan-African suture into Northeastern India. Precambrian Research, 152/1-2, 1-26. doi:10.1016/j.precamres.2006.08.011
• Crowley, J.L., Chatterjee, N., Bowring, S.A., Sylvester, P.J., Myers., J.S. and Searle, M.P. (2005) U-(Th)-Pb dating of monazite and xenotime by EMPA, LA-ICPMS, and IDTIMS: examples from the Yilgarn Craton and Himalayas. 15th Annual Goldschmidt Conference Abstracts, A19.

Send comments to e-probe-www@mit.edu

(Last Revised 11/29/2007 by Nilanjan Chatterjee)