The 15N Calibration Method

Methods       The Machine       Results
 
 

The Method

Hydrogen can be analyzed under high-vacuum by bombarding it with 15N ions from a linear accelerator.  The nuclear reaction scheme is shown below.  The 4.4 MeV gamma ray is emitted proportionally to the amount of H present in the sample.  By varying the energy of the incident 15N beam, it is possible to vary the depth the N beam penetrates into the sample before the nuclear resonance is excited.  In this way, a hydrogen depth profile can be measured.


 
 

This is an actual nuclear reaction profile obtained by the Frankfurt group on a kimberlite-hosted megacryst olivine from Kaalvallei, South Africa.  It shows a high concentration of 'water' on the surface of the crystal and a much lower internal OH content.

Results

olivine  kyanite

Olivine These results represent the state of the art for our analyses of olivine.  Near linear calibrations are obtained with minerals with several 10's to a few 100's ppm hydrogen (expressed as water) in the sample.
 

Reference:   Bell DR, Rossman GR, Maldener J, Endisch D, Rauch F (2003).  Hydroxide in olivine: A quantitative determinatin of the absolute amount and calibration of the IR spectrum. Journal of Geochemical Research, 108(B2), 2105, doi:10.1029/2001JB000679, 2003.











last revised: 23-Dec-2013