Posted on 17th November, 2011
TIMS produces absolute isotope ratio values rather than values normalized to a standard as is usual in gas IRMS. There is however always a small difference from machine to machine which explains why although modern TIMS systems can achieve a measurement precision of less than 5ppm, accuracy specifications are usually of the order of 25 or 30 ppm. Nevertheless we would expect instruments made in the same factory within a few...
Posted on 27th September, 2011
Sub-millimeter variations in Sr isotope ratios across zoned minerals and in fluid inclusions continue to be of interest to geologists. Whilst the use of ion microprobe systems provide the best spatial resolution, TIMS coupled with micro-milling devices provide the best accuracy and precision. Sample sizes are small – perhaps only a nanograms of Sr –...
Posted on 16th September, 2011
High sensitivity measurements of U are of crucial importance in a number of fields. Whilst atom/ion efficiency of >1% has been achieved for point source methods using carbon, for analyses of larger U loads (~500 ng) using a standard filament assembly with no carbon the typical atom/ion efficiency is in the range 0.005% to 0.01%. To test the ionization efficiency and precision achievable...
Posted on 29th July, 2011
A high precision Os note has been added to the downloads page. The wide interest in using Re/Os and Pt/Os in geochemistry and cosmochemistry make this a particularly important application. Phoenix includes a number of new developmental which significantly improve the negative ion performance compared to older generation machines. The application note provides the first detailed indication on the performance of the Phoenix system for Os and...
Posted on 29th March, 2011
This note describes the performance of the Phoenix TIMS for total evaporation of small U loads using three CRM’s. Total evaporation removes the need for a mass fractionation correction since ions from across the entire run are collected and summed. The note highlights the Phoenix’s ability to attain precision of 0.03%...
