Hi Mazhar, Usually time-resolved (pump-probe) XAS is measured in data set pairs at each X-ray energy: one with laser on, one with laser off. This means that you can always directly reference your laser-excited measurement to your laser un-excited measurement. To calibrate to an absolute scale you would then use a reference foil as normal and shift both data sets according to the reference values. If you had significant delays between your laser on/off measurements then drifts and other noise sources will affect your data, making it very difficult to determine a reliable difference signal. You could try to use a reference foil measurement to correct for these kinds of drifts but you need to be very careful with the corrections to ensure you aren’t just seeing an artifact. Ideally you would be measuring laser on/off differences on a millisecond to microsecond timescale between acquisitions, this gets rid of most of the possible noise sources. Best, Chris

On 30 May 2016, at 19:00 , ifeffit-request@millenia.cars.aps.anl.gov wrote:

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Today's Topics:

1. Regarding time resolved XAS (mazhar iqbal)

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Message: 1 Date: Mon, 30 May 2016 06:20:36 +0000 (UTC) From: mazhar iqbal To: "ifeffit@millenia.cars.aps.anl.gov" Subject: [Ifeffit] Regarding time resolved XAS Message-ID: <349705754.1395970.1464589236411.JavaMail.yahoo@mail.yahoo.com> Content-Type: text/plain; charset="utf-8"

hello.. I am sorry if am not posting on right place. I want to ask about the aligning the XAS spectra that is given in Athena. Can we do the alignment of time resolved spectra? As you know that the resolved spectra (IR pump X-ray probe) may have edge shift due to laser pumping. Do you think that the same method of the alignment can be applied here as well. An additional piece of information is that ?we have a reference fluorescence line always on the screen that well behind the K absorption edge. Hoping to see your response.? Best Regards