EasySpin forum

Posted: **Wed Jan 18, 2017 11:04 pm**

Hi! everyone. I'm trying to fit my experimental result from EPR spectrometer by EasySpin on MatLab. My spectra file were saved in form .DTA and .DSC. So, I wrote MaTLab for analysis this following by the code

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clear
[spc,Params,B] = eprload('1KGY1OCT2016.DSC');
spc = addnoise(spc,0.0000000000000000000000000000000000001,'n');
Sys0.g = [1.99, 2.07, 2.11];
Sys0.lw = 1;
Vary.lw = 0.3;
Vary.g = [0 0.02 0];
Vary.lw = 0.3;
Exp.mwFreq = 9.8;
Exp.Range = [200 400];
esfit('pepper',spc,Sys0,Vary,Exp);

The code was typed from Fitting EPR spectra section in website Easyspin http://easyspin.org/documentation/userg ... tting.html. The result from running the code shows as file 11.png.

: My fitting pannel; 11.png (80.58 KiB) Viewed 2822 times

I don't know why it is and think there is some mistakes which occurred in my EPR spectrum or I missed something (may be I have to do noise reduction of the spectrum before insert to fitting code ) in the code. I think if I write the good code, I will get the exact spectrum like this

: The real spectrum (horizontal axis has "G" unit).; 12.png (10.29 KiB) Viewed 2822 times

.

Moreover, I have also attached my ERP spectrum file as from .DTA and .DSC.
.DTA : https://drive.google.com/file/d/0B3uZI4 ... sp=sharing and .DSC : https://drive.google.com/file/d/0B3uZI4 ... sp=sharing
Thank you for all suggestions.

Posted: **Thu Jan 19, 2017 8:19 am**

The syntax of the eprload function is [x,y,Params] = eprload(FileName), so it is possible that you are loading your spectrum in the wrong order, i.e. [y,Params,x] in your example. I don't know whether ES can tell the difference, but you could try [B,spc,Params] = eprload('1KGY1OCT2016.DSC') and see if that does it.

Posted: **Fri Jan 20, 2017 2:23 am**

Thanks very much. I will try it!

Posted: **Mon Jan 23, 2017 4:34 am**

thanasis pointed out the wrong order in loading the file.
Next you use the

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addnoise

function with an assumed Signal-to-Noise ratio of 0.0000000000000000000000000000000000001. Is there any particular reason for that?
To perform a fit the structure

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Exp

should contain your experimental parameter. At least

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range

have to be different from what you posted, but probably also

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nPoints

, and

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mwFreq

.

In general the spectrum shown in the fit panel is the EPR spectrum. Note that it is normalized and has no units on the x-axis.

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