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Tectonics and Geochronology

Element ICP-MS Laboratory
with Excimer Laser Ablation System

ICP-MS

...means inductively coupled plasma mass spectrometry. We have a Thermo Scientific Element 2 for quantitative analysis of trace and ultratrace elements and isotope ratios in geological and non-geological samples.

How the ICP-MS works

The sample material is introduced into the spectrometer as an aerosol by argon carrier gas (for solution) or an Ar/He mixture for laser ablation. Aerosol particles are generated either by nebulizing a sample solution or by ablating solid material with a laser. When carried through the hot plasma (up to 8000 °C), the sample material is dissociated, atomized and ionized within milliseconds. The ions enter the mass spectrometer via the plasma interface, after which they are mass- and energy-filtered and the intensities at individual masses are determined.

The Element2

is a high-resolution, double focusing ICP mass spectrometer with very high sensitivity. Practical limits of detection are on the order of 1 ppt (= 1 part per trillion) for many elements and are generally better than 100 ppt. The Element2 has three resolution modes: low (resolution = 300), medium (resolution = 4,000), and high (resolution = 10,000). Medium and high resolution modes provide separation of the analyte signal from spectral interferences, making accurate and precise elemental analysis of trace element in complex matrices possible. The ion beam passes through a magnetic field generated by a large magnet. The magnetic field is dispersive with respect to ion energy and mass. The second focusing occurs at the electro-static analyzer or ESA. The ESA is dispersive with respect to ion energy and focuses the ion beam through the exit slit to the detector.

Specifications

Sensitivity: > 1 x 109 cps/ppm for In
Detection Limits: < 1 ppq (theoretical, non-interfered)
Dark Noise: < 0.2 cps
Dynamic Range: > 109 linear


The Element2 with ESI autosampler on the left, the Photon-machines ANALYTE 193nm ArF excimer laser on the right (May 2009).

Sample types

Liquid and solid samples will be analyzed. For solution ICP-MS, solid materials are dissolved with ultrapure acids and procedures. Carbonates are simply dissolved in diluted nitric acid. Silicate rocks can be decomposed by concentrated nitric acid, hydrochloric acid and hydrofluoric acid and heating at ca. 200 °C in teflon beakers or stainless steel pressure vessels. An Elemental Scientific (ESI) autosampler dedicated to the Element2 (SC-E2 with FAST) will be attached directly to the ICP-MS onto the nebulizer side of the instrument. This will be used to develop innovative methods of sample introduction and isotope ratio measurements together with ESI (link to ESI hompage: http://www.elementalscientific.com/default.asp

For in-situ laser ablation ICP-MS, the sample can be any type of solid. A 193 nm wavelength, ultra short pulse ArF Excimer laser has been acquired. U-Th-Pb geochronology, trace element fingerprinting and trace element thermometry will be the main applications for this set-up. Short, ca. 4 ns, pulsing of the laser minimizes heating of the area around the ablation pits and produce flat-bottomed craters without melting. The 193 nm wavelength produces small particles that will minimize element fractionation, and provides excellent coupling of the laser with materials of different color and transparency.

Prospective Ph.D. and M.S. research and postdoctoral researchers who wish to work on research topics in geochronology, crustal evolution, geochemistry, metamorphic petrology, please contact Andreas Moeller (link to hompepage: http://www.geo.ku.edu/programs/tectonics/moller.shtml) (amoller@ku.edu). There are possibilities for graduate research funding (link: http://www.geo.ku.edu/programs/tectonics/opportunities.shtml). Requests for collaboration and analytical services will also be welcome from academic as well as industrial customers.

Laboratory Equipment


Thermo Scientific Element 2 ICP-MS
Photon-machines ANALYTE.193, 193 nm ArF excimer laser ablation system
Autosampler ESI SC-E2 with FAST valve

Support equipment:
15kWh UPS system
ThermoScientific Neslab Thermoflex 2500 chiller