# Peak width of Gaussian fitting

yangzheng

Thu, 03/07/2013 - 03:34 pm

I am doing photoelectron spectroscopy. The peak width defines our resolution. Usually we use FWHM as peak "width". But I saw two numbers in the fitting results. One is FWHM, the other is "Width" under "Fit function parameters". The "FWHM" is larger than "Width". My question is what is the define of this "Width".

The result is pasted here:

Peak 0 Type: Gauss

Location = 2.7105 +/- 6.1234e-06

Height = 0.88553 +/- 0.0089955

Area = 0.0011648 +/- 1.2348e-05

FWHM = 0.0012357 +/- 1.4631e-05

Fit function parameters

Location = 2.7105 +/- 6.1234e-06

Width = 0.0007421 +/- 8.7866e-06

Height = 0.88553 +/- 0.0089955

FWHM can be calculated from the standard deviation. Approx. 2.354*s.d. So for your numbers = 0.00123525.

March 7, 2013 at 11:50 pm - Permalink

Are you aware ...

The Gaussian peak in statistics is defined as ...

P(x) = \frac{1}{\sqrt{2\pi}\sigma}\ \exp\left[- \left(\frac{1}{2}\right)\left(\frac{x - \mu}{\sigma} \right)^2 \right]

... where P(x) is probability, \sigma is the standard deviation of the distribution, and \mu is the mean of the distribution.

The Gaussian peak in XPS/UPS is defined as ...

I(E) = h\ \exp\left(-4\ \frac{\ln(2)(E - p)^2}{w^2} \right)

... where I(E) is intensity, E is energy (BE or KE), h is peak height, p is peak position, and w is the width at half-maximum height.

The parameters of the two are defined as shown in this table.

(the LaTeX equations can be parsed from ... http://www.codecogs.com/latex/eqneditor.php)

--

J. J. Weimer

Chemistry / Chemical & Materials Engineering, UAHuntsville

March 8, 2013 at 07:57 am - Permalink

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