Line width in CW spectra

[kasra]

Dear easyspin group,

Is there a way to measure line width when I use garlic function?
I want to measure the line width variation in presence of different amount of paramagnetic centers, but it dose not possible with defining 'lw' in spin system.

Please guide me.
Thanks.
Kasra

[katarkon]

I propose You should vary only Lorenzian part of lw field. Gaussian one should be a constant.

[kasra]

Thanks for your help, but it dose not work.
This is what I wrote:

Sys1 = struct('g', 2.0059, 'Nucs', '14N', 'A', 40, 'lw',[0.2 0.4]); %nitroxide
Sys1.weight=1;
Sys2 = struct('g', 2.25, 'Nucs', 'Cu','lw',[0.1 0.4]);
Sys2.A=mt2mhz(18);
Sys2.weight=0.5;
Exp.mwFreq = 9.5;
Exp.Range = [250 354.8];
garlic({Sys1,Sys2},Exp);

Changing the Sys.weight2 does not change the line width of the nitroxide spectrum.

[katarkon]

Try to vary second Sys1.lw parameter. Also chili() function with Sys1.Exchange parameter should be used.

[kasra]

I tried to vary second parameter of sys2.lw and I defined some different values, but again the results did not change with changing the sys2.weight parameter.
I am sorry but I am new in this field, I use garlic because of the liquid phase of nitroxide.

[katarkon]

I don't completely understand what problem you try to solve. I propose that you want to find the dependence of first component linewidth from second component concentration, isn't it? If it's so, you must vary both Sys1.lw and Sys2.weight simultaneously. Note that Sys.lw is generally consists of two components which are responsible for lineshape. First one is gaussian part and it should be a constant. Second one is a lorenzian part and only this component should be varied.

[kasra]

Thanks for your attention and guidance.
You properly understand my problem, but your way does not answer, because the line width vary independent of second component concentration and just base on 'lw' which has been defined.

Please let me change the topic.
Generally, I want to get spectra from various concentration of contrast agent and I want to obtain a relation between an EPR spectrum variation and contrast agent concentration changes. Imagine that, there are some mediums with same sizes which have filled of different concentration of nitroxide free radical. How could easyspin spectrum guide me to measure the nitroxide concentration?

[katarkon]

I suggest that second spectrum is an internal standard with known concentration. Is it so?

[kasra]

I don't think so. I could not find this reference spectrum.

[katarkon]

I'm afraid that absolute concentration measurements are impossible by EPR without the standard. If you want to measure the relative concentration, you should use double integral intensity of the experimental spectrum. There are no need in simulation generally, although it can be used for more precise integration (in the case of noisy spectra, uncorrectable baseline, etc.).