The IMSE works in partnership with the Nano Research Facility to serve the needs of materials researchers at Washington University and beyond. The NRF administers additional equipment focused on the synthesis and characterization of nanostructured materials.
Neptune Plus Multi-Collector Inductively Coupled Mass Spectrometer (MC-ICP-MS)
Primary Point of Contact: Dr. Jeffrey Catalano 314-935-6015
The Department of Earth and Planetary Sciences, a participating department of the IMSE, operates a Neptune Plus Multi-Collector Inductively Coupled Mass Spectrometer (MC-ICP-MS) as a user facility available to scientists at Washington University and the surrounding region. The main scientific instrument in the Isotope Cosmochemistry Lab is a Thermo-Scientific Neptune Plus MC-ICP-MS. Multi-Collector ICP-MS instruments have been developed in the last 20 years in order to measure the isotopic composition of most elements at precisions relevant to geological and cosmochemical studies.
At present, only two manufacturers produce MC-ICP-MSs: Nu Instruments and Thermoscientific. The main difference is that in the Nu MC-ICP-MS, the alignment of isotopic beams into the detectors is achieved by optical tuning, whereas in Neptune instruments, detectors are physically moved to be aligned with ion beams. As a result, the tuning of a Neptune tends to be in easier and more stable.
The Isotope Cosmochemistry Laboratory’s Neptune was installed by Thermo engineers in November 2010. It has the standard Neptune Plus configuration without jet interface. The detectors are 9 Faraday cups and 1 ion counter. Faraday cups are coupled to resistors from 109Ω to 1010Ω which delivers an effective dynamic range from 0-50V to 0-500V. Measurements can be performed in low-resolution mode for maximum sensitivity, medium and high-resolution modes for eliminating poly-atomic isobaric interferences with a maximum resolving power of around m/∆m = 8000. Hence interferences such as 40Ar16O with 56Fe can be removed but not mono-atomic interferences (e.g. 54Cr and 54Fe).
The Neptune Plus is also equipped with an ESI Apex Q desolvating nebulizer. This allows for higher sensitivity (about x4) and reduces oxide and hydride interferences. An ESI SC-micro with enclosure autosampler is also used for automated sample analysis.
The instrument has performed satisfactorily over the last 3.5 years with a few breakdowns due mostly to failures of power supplies and in the cooling systems which were fixed by replacing defective parts. It is at present in good working order. Across all measured elements, internal precisions of better than 0.05 permil are routinely achieved.
The Neptune is capable of measuring isotopic ratios for every element of the periodic table except a few light elements such as C, N, O, S. Effectively, many elements have been analyzed successfully on this particular instrument and have led to publications: Si, Ca, Cr, Fe, Cu, Zn, Sr. Other elements have also been analyzed successfully with results not yet published: Mg, Ga, Ni, Rb, Sn, Ba. Analysis of heavier elements such as Nd, Pb, U are also possible.
Primary point of contact: Dr. Paul Carpenter
The Department of Earth and Planetary Sciences, a participating department of the IMSE, operates a powder X-ray diffractometer as a user facility available to scientists at Washington University and the surrounding region. This facility recently installed (November 2012) a Bruker D8 Advance powder diffractometer with a 3.0 kW generator, a Cu Kα X-ray source, and a LynxEye XE energy-dispersive strip detector for measuring 3° of 2θ at once without the need for a monochromator or Kβ filter. This replaced an existing powder XRD instrument (ca. 1982) and provides a factor of 200 to 400 reduction in data collection time, or a similar improvement in data quality, over traditional powder XRD instruments. The XRD laboratory provides users with access to the Bruker software EVA and TOPAS for data analysis, including phase identification, structure refinement, and quantitative phase analysis. The lab also maintains multiple diffraction and structural databases, including the ICDD powder diffraction file (PDF) database.
MEMS has shared materials testing equipment available