Full Width at Half Maximum (FWHM) & Quadratic equation
Full width at half maximum (FWHM) for a curve is used in many scientific experimental data analyses. For instance, in X–ray diffraction analysis of crystal data, it is used to find the grain size from the curve. FWHM is the width of the curve or simply the difference in the corresponding two ‘x’ data values at y max /2. y max refers the highest value of ‘y’ or ‘y’ value for the maximum peak height. Example Set of ‘x’ and ‘y’ data and the corresponding curve is given below: (View this Page for back reference.) x y 0.0 0.000 0.1 0.146 0.2 0.284 0.3 0.414 0.4 0.536 0.5 0.650 0.6 0.756 0.7 0.854 0.8 0.944 0.9 1.026 1.0 1.100 1.1 1.166 1.2 1.224 1.3 1.274 1.4 1.316 1.5 1.350 1.6 1.376 1.7 1.394 1.8 1.404 1.9 1.406 2.0 1.400 2.1 1.386 2.2 1.364 2.3 1.334 2.4 1.296 2.5 1.250 2.6 1.196 2.7 1.134 2.8 1.064 2.9