Hi experts. can anyone give me some details about the advantages of FWHM? is the narrower better than wider? and why? How to explain that in a scientific way so that it can be clear for any reader to understand. Thanks in advance.
FWHM is a standard way of describing the transmission characteristics of an optical bandpass filter, describing the width of the spectrum at the wavelengths that the filter passes, in nanometers. Whether you want a wider or narrower bandpass depends on the application. A wider bandpass allows more of the spectrum through, but is less wavelength-selective.
Here is a nice description, with diagram:
https://www.edmundoptics.com/resources/application-notes/optics/optical-filters/
According to sherrer equation mean crystal size = (kλ)/(β cos θ),
if the wide FWHM that will produce small crystal size toward nanomaterials......
FWHM is a standard way of describing the transmission characteristics of an optical bandpass filter, describing the width of the spectrum at the wavelengths that the filter passes, in nanometers. Whether you want a wider or narrower bandpass depends on the application. A wider bandpass allows more of the spectrum through, but is less wavelength-selective.
Here is a nice description, with diagram:
https://www.edmundoptics.com/resources/application-notes/optics/optical-filters/
FWHM is more or less stable parameter of the absorption band at given temperature and pressure, whereas the width depends on concentration of the absorption centers. And the parameter "width" is not much definite, when the tails of the band are considered.
Another important aspect of FWHM is that it can be used as a figure of merit for the quality of emission in devices like LEDs, specifically if a narrow spectral emission is required. As an example, in display applications where you typically will use three colored emitters (red, green, blue), you would like to have emitters that are spectrally as narrow as possible in their respective wavelength region (meaning a small FWHM). This way, you would be able to cover more of the color gamut (cf. Fig. 10 of this paper: https://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.6b00954?rand=ill7hrb1; and Fig. 3 of this paper: https://pubs.rsc.org/en/content/articlehtml/2018/nj/c8nj02135j; and Fig. 7 of this paper: Article Electroluminescent and Optoelectronic Properties of OLEDs wi...
).Another application where FWHM is used would be in determining the q-factor for resonating devices (https://en.wikipedia.org/wiki/Q_factor#Resonant_devices). This is somewhat important in all sorts of lasing applications.
In genetal term, full width at half maximum (FWHM)
is an expression of the extent of function given by the difference between the two extreme value of the independent variable at which the dependent variable is equal to half of its maximum value. (https://en.m.wikipedia.org/wiki/Full_width_at_half_maximum)
The above link gives a clear explanation why FWHM has been widely used in optical communications and the resolution of spectrometers or spectroscopy analysis and signal processing. It is also applied in the duration of pulse waveforms in the time variable.
The definition of FWHM is useful in term of mathematical calculation of a function as an important parameter.
Dear,
the Full width at half maximum of what kinf of characterization. You should specify
@Abdelmounaim Chetoui Please see the link in my answer to explain the definition and characteristics of FWHM used for different physical meanings and functions.
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