DMPO adduct - Correlation Time assistance

[baillied]

Hi all,

I am attempting to simulate a DMPO-OOH adduct at room temperature. Currently, I am able to do a decent job simulating the data, but am unable to replicate the slant I observe in my spectra which I presume is because I need to figure out the correlation time. However, every time I try to simulate a stacked spectra with various correlation times it tells me there is an error in garlic and that I have negative line width value and it must be positive. I have attached a photo of my simulation and my input and any advice that you can give me on figuring out how to continue would be greatly appreciated. This is my first time simulating spectra and the examples have helped a lot, but I am stumped as to where to go from here.

Here is the input I have been using to get me this far:

% DMPO-OOH Adduct Simulation - Take 50000
%---------------------------------------------------------
%---------------------------------------------------------

%loading experimental files
%---------------------------------------------------------
easyspin %opens Easyspin software in Matlab
[B,spc] = eprload (‘C:\Users\Shimizu\Desktop\Baillie\Host15minUV’); %Open EPR files
plot (B, spc) %plot data – a window of the plotted data should pop up.

%Parameters
%---------------------------------------------------------
Sys.S = 1/2; %Overall spin of the system
Sys.g = [2.0075]; %for an isotropic g, for one electron spin
Sys.Nucs = '14N,1H'; %nuclei involved
Sys.A_N = mt2mhz([13.1]/10); % G --> MHz (aN)
Sys.A_H = mt2mhz([10.8]/10); % G --> MHz (aH)
Sys.A = [Sys.A_N, Sys.A_H]; %splitting constants
Sys.lw = 0.35; % this line width has gotten most accurate looking spectra so far

% Simulation
%---------------------------------------------------------------------
Exp.mwFreq = 9.382047; %the microwave frequency
Exp.Range = [327.5 342.5]; %the range you scanned in mT
Vary.g = [0.05]; %this will vary the g-value during the simulation which will in turn give you the best g-value from the fit.
SimOpt.method=’perturb’;
FitOpt.Method = ‘simplex int’;

% Plotting
%---------------------------------------------------------------------
spc = addnoise(spc,150,'n'); %add noise
esfit(‘garlic’, spc,Sys,Vary,Exp,SimOpt,FitOpt);

[Stefan Stoll]

In order to determine a correlation time, you need to include information about the anisotropy of the various hyperfine tensors. These anisotropies determine how wide the lines are for a given rotational correlation time. See fastmotion and garlic.