Hyperfine Isotopes

[JamesS]

Hello,
For CW simulation, if I don't state the isotope and give one hyperfine value how does Easyspin assign the hyperfine values? For example, if I write Cu and give it a value of 150 MHz. What hypefine values will Easyspin assign to 63Cu and 65Cu?

Thank you and best wishes,

James

[trukhan]

Hello!
If you set A = 150 MHz and Nucs = 'Cu' then EasySpin will assign
A(63Cu) = 150 MHz
A(65Cu) = 150 MHz * nucgval ('65Cu') / nucgval ('63Cu') = 150 MHz * 1.5878 / 1.4824 = 160.7 MHz

You can understand this from the following example:

Code: Select all

clear

% Component 1
Cu63.g = [2.000 2.100];
Cu63.A = [mt2mhz(1,Cu63.g(1)) mt2mhz(5,Cu63.g(2))]; % MHz
Cu63.Nucs = '63Cu';
Cu63.lwpp = 0.3;        % mT

% Component 2
Cu65.g = Cu63.g;
Cu65.A = Cu63.A*nucgval('65Cu')/nucgval('63Cu');    % MHz
Cu65.Nucs = '65Cu';
Cu65.lwpp = Cu63.lwpp; % mT

% Natural abundance
Cu.g = Cu63.g;
Cu.A = Cu63.A;     % MHz
Cu.Nucs = 'Cu';
Cu.lwpp = Cu63.lwpp; % mT

% Relative abundances
 Cu63.weight = nucabund('63Cu');
 Cu65.weight = 1-Cu63.weight;
 Cu.weight = 1;

% Experimental parameters
Xband.mwFreq = 9.773;         % GHz
Xband.Range = [320 355];     % mT

[B,s1]=pepper(Cu63,Xband);
[B,s2]=pepper(Cu65,Xband);
[B,s3]=pepper(Cu,Xband);
shiftY=0;
plot(B,s1,'r',B,s2,'b',B,s1+s2+10,'k',B,s3+11,'g'); axis tight
legend('^6^3Cu','^6^5Cu','69% ^6^3Cu + 31% ^6^5Cu','Cu','Location','northwest');
grid on;
set(gca,'xtick',[325:5:355]);

Cu_isotopes.png (19.98 KiB) Viewed 1963 times

[JamesS]

Thanks a lot for your work on this.

I assume the reference point is always the isotope with the greater natural abundance? Then, as you have shown, it scales with nuclear g value.

[Stefan Stoll]

Yes, correct. For hyperfine couplings, it's the most-abundant isotope. This is documented on the page about spin system, for Sys.Nucs.