How To Use The New Laser Log File Importer

Here is a quick demo of the new laser log file importer:

CellSpace images tutorial

The Iolite team and Ash Norris from Resonetics have been working on a new way of creating images. We take the spatial information recorded in laser log files and combine that with mass spec data to produce images of composition versus sampling position in the laser cell. This has some great advantages:
-images don't need to be of regular shape;
-image scans don't have to be sequential (so you can measure your reference materials between scans, or several times over the course of collecting an image);
-and, you can plot your laser ablation image over mapped images of your sample collected by other means, such as photomicrographs, SEM images etc.

Here's a tutorial, using an otolith (part of a fish's auditory system) to illustrate how to create a CellSpace image, and how it can be displayed over another image. You can download the example files from this page (at the bottom) to follow along. And if you're not familiar with using laser log files, you might want to visit this page first.

[Note: Aglient users may have issues synching the example laser log file and Agilent data. If so, please delete the AgilentDateFormat.txt file in the "Other Files" subfolder within your Iolite folder and try importing the example data again.]

And just to illustrate how this approach can save time, here's a figure of how the image scan lines were arranged (green lines in right-most image) over the otolith (shown without scan lines on left and center). You can see we mostly avoid the epoxy mount, saving time and reducing the amount of gunk put into the mass spec:

Unfortunately the mouse position was not captured very well by the recording software. If you have any questions, feel free to post on the forum.

Masking your results in Iolite - tips and pitfalls

REMEMBER, masking is on by default! So watch this video to find out how masking affects your data! Included is a brief example of how masking works and how masking can affect your results. Also includes things to look out for when setting mask thresholds. If you have any comments or questions, please post on the Iolite forum at http://iolite.earthsci.unimelb.edu.au/forum/

Selecting integration periods automatically (Part 2)

As promised, this post will cover the 3rd option of automatic integration selection called "detect from beam intensity". This option allows you to select portions of your data that satisfy up to three different criteria (e.g., where U238 is greater than 10000 counts per second). Because such criteria are independent of how your data were collected (e.g., numerous small files vs. a single large file), the method is particularly useful for sessions that don't include some sort of labelling for each analysis. This first short video demonstrates the basics of the interface using a U-Pb dataset as an example:



So you would have noticed the extra level of feedback in this option, with the graph showing not only the location of each integration period, but also which ones you've selected, and the location of any pre-existing integration periods for the selected integration type.

But there's one other thing about this new option which we think makes it really powerful, which is that in addition to your input channels you can also use intermediate and output channels as selection criteria. This means you can use an isotopic ratio, or even the calculated 206/238 age of an analysis to distinguish between analyses, as this next video demonstrates:



The other benefit of being able to use intermediate and output channels is that anyone who's really keen can make waves in their DRS specifically for assisting in selecting integrations. For example, you could make an intermediate wave that is given the value 0 for all parts of your data that you don't want to select, and the value 1 for time intervals of interest, then use this wave as your selection criterion in the "detect from beam intensity" interface. In this way, you could either come up with discriminating criteria that are more complex than what's provided in the current interface, or just make your life a little easier by, for example, rolling three different criteria into a single wave, so that you don't need to set everything up in the interface every time you use it.

Selecting integration periods automatically (Part 1)

For anyone trying to process an even moderately sized dataset, the ability to select integration periods automatically is a huge timesaver. In addition, if you're trying for reproducibility in the way you're selecting each analysis, using an automated approach makes this a lot easier than trying to manually select exactly the same intervals over and over again.

Iolite has several ways for you to select integrations automatically, and these will be the focus of a couple of separate blog posts. In this post, I'm going to show you how to use the "information from import" option, which is most useful for sessions consisting of numerous discrete analyses (either in separate files or within a single file). For those of you acquiring laser log files, you can use the "laser log file" option, and the actual selection of integration periods will be virtually identical to what's presented here (there's a bit of extra stuff for synchronising your laser log file with your acquired data, but I'm not going to go into that here).

If your analyses were all acquired in large files, you won't get much benefit from this approach, but luckily for you we've just added a 3rd option called "detect from beam intensity". It's quite a powerful tool that uses channels from your DRS to discriminate time periods of interest, but it will have an entire post to itself in the near future, so I won't go into it more here...

So now to the main event – I've put together the following video to walk you through the process of selecting integration periods automatically:

What do data look like in Iolite?

This is another introductory post for those of you who are new to Iolite and are wondering what we mean when we say that Iolite is all about data visualisation. The video gives you a quick tour of what mass spectrometer data looks like in Iolite.



More specifically, in this video I look at a session about one hour in duration, in which a number of kimberlitic perovskites were sampled by laser ablation. Strontium isotope measurements were acquired (on a Nu MC-ICPMS) at 5 Hz (every 0.2 seconds), with an extended period of gas blank (normal operating conditions, but without the laser firing) at the beginning and end of the analysis. Each spot analysis consisted of approx. 60 seconds of ablation, followed by movement to the next spot position, and a short period of gas blank acquisition. The session consisted of fourteen analyses of sample perovskites, bracketed before and after by three measurements of the 83P13 in-house perovskite standard. If you're really keen on finding out more about the method used,  take a look at http://onlinelibrary.wiley.com/doi/10.1111/j.1751-908X.2007.00131.x/abstract

Using the mouse to navigate your data in Iolite

Here's a quick video demonstrating how you can move around your data in Iolite.



Sorry about the sound quality, I'm working on it!