Standard digitized positions vs Re-standard increments

[KerstinGruender]

Hi,

we're getting noticeable drift on some elements at the moment, most likley due to temperature fluctuations/air pressure, thus I'm wanting to use the PfE feature where standards are acquired every few hours during a long run. I have two questions I cannot find the answer to, neither in the manual or in here:
1. If I use 'only digitized std positions' (I usually do for calibration due to some flyspeck standards), plus I have it set to acquire 4 std points, if I then want to automatically re-standard later during a run - will PfE go to the same points it has already analyzed (i.e. first in the list) or 'keep going' to the next available digitised point. In which case I could pre-emptively set like 10+ points to have enough 'new' ones for recalibrations? Or is re-standard using the increments even if I have digitized only ticked?
2. If using the increments option (i.e., digitized positions not ticked) which direction does it move? I've tried it but it's not clear which direction it moved, i.e. left or right/up or down? Does it start incrementing from the last point analyzed or the initially digitised position(s)? essentially I need to know where I need to find an L-shape or square-shaped clear spot in the horizontal/vertical direction. If using 20um beam size the movement could potentially take it off-grain for a few of our standards because they're elongate.

Cheers,
Kerstin

[John Donovan]

we're getting noticeable drift on some elements at the moment, most likley due to temperature fluctuations/air pressure, thus I'm wanting to use the PfE feature where standards are acquired every few hours during a long run. I have two questions I cannot find the answer to, neither in the manual or in here:
1. If I use 'only digitized std positions' (I usually do for calibration due to some flyspeck standards), plus I have it set to acquire 4 std points, if I then want to automatically re-standard later during a run - will PfE go to the same points it has already analyzed (i.e. first in the list) or 'keep going' to the next available digitised point. In which case I could pre-emptively set like 10+ points to have enough 'new' ones for recalibrations? Or is re-standard using the increments even if I have digitized only ticked?

First of all, "flyspeck" standards are not really "standards"!    

(Sorry, for the old man rant here!) When I started in microanalysis back in the 1980s, I spent an afternoon in the Earth Science library at UC Berkeley going through the last 10 years of American Mineralogists issues and noting the author and address of every article that described a new standard material and wrote them (you know, with a pen and paper, in an envelope with a stamp to 100 different authors!), and over the next few weeks I received an amazing number and quantity of beautiful materials, mostly synthetic single crystals, which I then characterized using various techniques, most of which I still use.

Today however, there is a large number of high purity, synthetic minerals which we can utilize as primary standards for our analyses, because our matrix corrections, dead time corrections, etc, have improved so much that we no longer need to depend on "matrix matched" standards of unknown composition, purity and homogeneity:

https://smf.probesoftware.com/index.php?topic=1415.0

In other words, get better standards! It will make your life so much easier and your analyses will be vastly improved.

As for your question, well, it would be easy enough to test yourself! But I did a quick test run (in simulation mode) just to see for myself (because I wanted to be sure I was being accurate), and so I set up a test run with two points (same stage coordinates) in my Ti std, then set the X and Y increments to 30 and 50 um respectively (to make it completely clear) as seen here:



and of course I checked the Use Digitized Positions Only checkbox in the Acquisition Options dialog from the Acquire! window as you did, and ran them from the Automate! window.

After plotting up the stage positions for the acquired points we obtain this:

2. If using the increments option (i.e., digitized positions not ticked) which direction does it move? I've tried it but it's not clear which direction it moved, i.e. left or right/up or down? Does it start incrementing from the last point analyzed or the initially digitised position(s)? essentially I need to know where I need to find an L-shape or square-shaped clear spot in the horizontal/vertical direction. If using 20um beam size the movement could potentially take it off-grain for a few of our standards because they're elongate.

The X and Y increments are applied as seen in the above screen snap of the Automate! window. If set to 50 um the stage will be incremented by 50 um for points without a digitized point (unless the Use Digitized Positions Only checkbox is checked).  On the JEOL instrument (which is anti-Cartesian), that means to the lower left.

You can use negative increments if you want to move in the other direction, or you can set them to zero if you want no stage movement between points (not recommended for materials that are at all beam sensitive!).

Sorry for the long response, but I hope this helps.

[KerstinGruender]

Thanks John, that's exactly what I'm after

If I had 10 points digitised, and only used 2 or 3 per set, would it then use the unused ones for the next round of re-standard or increments regardless?

Ha, I knew you'd say that about the 'standards' I'm analysing minerals and glass in peralkaline rhyolite, including for fluorine, which leaves me with somewhat limited choices... If someone has a good standard for Na in glasses, let me know! (we have KN18 and VG568)

Cheers,
Kerstin

[John Donovan]

If I had 10 points digitised, and only used 2 or 3 per set, would it then use the unused ones for the next round of re-standard or increments regardless?

No, it would use the number of digitized points specified and start at the beginning for each re-standardization. But it will apply the X and/or Y increment as specified also.

Ha, I knew you'd say that about the 'standards' I'm analysing minerals and glass in peralkaline rhyolite, including for fluorine, which leaves me with somewhat limited choices... If someone has a good standard for Na in glasses, let me know! (we have KN18 and VG568)

Yeah, a Na silicate is turning out to be the most difficult synthetic standard to find.  We may have to depend on a natural feldspar for our new FIGMAS mounts:

https://smf.probesoftware.com/index.php?topic=1415.msg10368#msg10368

but if we did it would need to be a very pure end member albite where the traces have been analyzed carefully and check for homogeneity.  I did just that with my Cazadero Albite standard material which I developed at UC Berkeley back in the day:

St  301 Albite (cazadero)
TakeOff = 40.0  KiloVolt = 15.0  Density =  2.610  Type = feldspar  Mount = hydrous, carbonate

Specimen from HR Wenk, UC Berkeley, Geology
See Wenk and Kroll, Bull. Mineral. (1984), 107, 467-487
K=140 ppm, Sr=9 ppm, Rb=0.14 ppm (Isotope dilution)
Oxide and Elemental Composition

Average Total Oxygen:       48.807     Average Total Weight%:  100.149
Average Calculated Oxygen:  48.809     Average Atomic Number:   10.708
Average Excess Oxygen:       -.002     Average Atomic Weight:   20.178

ELEM:     SiO2   Al2O3    Na2O     K2O     CaO       O
XRAY:      ka      ka      ka      ka      ka      ka 
OXWT:   68.241  19.900  11.940    .040    .029   -.002
ELWT:   31.898  10.532   8.858    .033    .021  48.807
ATWT:   28.086  26.982  22.990  39.102  40.080  16.000
KFAC:    .2510   .0807   .0511   .0003   .0002   .2554
ZCOR:   1.2711  1.3047  1.7351  1.1561  1.1096  1.9110
AT% :   22.883   7.865   7.763    .017    .011  61.462
24 O:    8.936   3.071   3.031    .007    .004  24.000