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jwoh
2 Posts |
 Posted - 09/03/2020 : 12:01:23 AM
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Hi everyone.
I got the data for the integrated photoluminescence intensity as a function of temperature.
To find the activation energy, I changed the x-axis to 1000/T and the y-axis to ln(y) and then fitted the Arrhenius equation with a user-defined function.
However, the message 'Fit did not converge-reason unknown' continuously appear.
The functions, variables, and parameters I used are as follows.
Independent Variables: T
Dependent Variables: I
Parameter Names: A, E
Function Form: Origin C
Function:
I=I0/(1+A*exp(-E/kT))
Constants:
I0= integrated PL intensity at 0K
k=1.38*10^(-23); boltzmanm constant
Please let me know what needs to be corrected or supplemented.
In addition, please inform me of Parameter Initialization.
Thank you. |
Edited by - jwoh on 09/03/2020 02:32:00 AM |
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Shirley_GZ
China
Posts |
Posted - 09/03/2020 : 03:00:52 AM
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Hi Jwoh,
The function body should be defined as below:
And, the initial value for parameter E should have similar magnitude with the parameter k, such as 1E-22
Please correct the function and try to do the fitting again.
Thanks,
Shirley
Originlab Technical Service Team |
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jwoh
2 Posts |
Posted - 09/03/2020 : 07:04:27 AM
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Hi Shirley.
With your advice, the fitting was successful.
Thank you.
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Huda.S
Saudi Arabia
2 Posts |
Posted - 04/06/2022 : 08:09:32 AM
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Hello
I followed the previous steps but there is a place for the constants and I put k (Boltzmann's constant) but it didn't ask to define the value for it
Is this considered to be predefined in the program by the value of the constant 8.6*10^-5 ev/k-1
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ChaoC
USA
178 Posts |
Posted - 04/06/2022 : 09:03:08 AM
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Hi Huda.S,
If you go to Tools>Fitting Function Builder you can define k as a constant in the Variables and Parameters section. Then, on the next page you can switch to the Constants tab and define Boltzmann's constant.
Chao |
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Huda.S
Saudi Arabia
2 Posts |
Posted - 04/08/2022 : 2:07:56 PM
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Hi Chao
I try it, it is work
thank you too much |
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Topic |
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arrhenius plot : user-defined function