Hf isotopes DRS

Yousef

Hi iolite team,

Is there a DRS for Hf isotopes in iolite4 that corrects for the interference of 176Yb over 176 Hf? (i.e., the final data should not show a positive correlation between 176Yb/177Hf and 176Hf/177Hf). The 'Hf Isotopes' DRS that comes with iolit4 does not do this correction. A friend told me that there is one on the iolite Github page, but those that I was able to find in the following link do not do the job. Maybe I have the wrong link!?
https://github.com/iolite-LA-ICP-MS/iolite4-python-examples/tree/master/drs

Best regards,
Yousef

Yousef

To clarify, I should say that I could not try the DRS by Graham in the link above (Hf_isotope_XBeta) as it required extra channels that iolite could not find in my data files (data are produced via LA-ICP-MS).

Thanks.

Joe

Yousef

The built-in DRS does do some correction of Yb on Hf, maybe not the one you're after? The built-in DRS is very similar to the python example here: https://github.com/iolite-LA-ICP-MS/iolite4-python-examples/blob/master/drs/Hf_isotopes.py, where you can see Yb and Lu being removed from mass 176 ~ lines 67-69.

In my quick test here, this did seem to flatten 176Hf/177Hf vs 176Yb/177Hf. For example, here are the "raw" ratios showing the correlation:

And the corrected 176Hf/177Hf on the same magnitude of Y scale:

And finally with the Y scale fit tighter there is no apparent correlation:

That said, Graham's DRS does do some extra stuff and is worth checking out. I suspect that it isn't finding things for you because his script is hard coded to use "m###" channel names. Some multi-collectors give us channel names like that. Have you measured 179, 177, 176, 175, 173 and 171? If so, you can open the Hf_isotopes_XBeta.py file with a plain text editor and edit the data.timeSeries(...) calls to data.timeSeriesByMass(...) or simply replace the hard coded channel names with what you have. For example,

Hf179 = data.timeSeries("m179_CPS").data()
# becomes
Hf179 = data.timeSeries("Hf179_CPS").data()
# OR
Hf179 = data.timeSeriesByMass(data.Intermediate, 179, 0.2).data()

All the best,

Yousef

Thanks Joe,

I could not get the "raw" rations for 176Hf/177Hf vs 176Lu/177Hf you have shown above using the Python DRS example on the Github page. It also does not report 176Yb/177Hf. So no way to see if it does the corrections. I have attached screenshots of all reported channels.
It also seems that the DRS by Graham needs analysis of a high Yb standard, which I do not have in my data.

Here is a plot of 176Yb/177Hf vs 176Hf/177Hf using the built in Hf DRS of iolite. It seems it does not doe the corrections:

Yousef

Or maybe the inbuilt Hf DRS does this correction and normalizes the data to the reference material, in this case Mud Tank, which contains less 76Yb than the unknowns, and hence the correction done is not enough for my unknowns.
The question would be how to extend the correction range to also include the high Yb content of my grains (over correction).