PsdVoigt2

Contents

Function

y=y_0+A\left[ m_u\frac 2\pi \frac{w_L}{4\left( x-x_c\right) ^2+w_L^2}+\left( 1-m_u\right) \frac{\sqrt{4\ln 2}}{\sqrt{\pi}w_G}e^{-\frac{4\ln 2}{w_G^2}\left( x-x_c\right) ^2}\right]

Brief Description

While Vogit peak function is the convolution of a Gaussian curve G(x) and a Lorentzian curve L(x), the Pseudo-Voigt peak function is an approximation of the Voigt peak function which instead using a linear-combination of Gaussian curve G(x) and a Lorentzian curve L(x).

Origin provides two types of Pseudo-Vogit peak functions: PsdVogit1 and PsdVogit2. When using PsdVogit1, you can only specify one FWHM value denoted as w which will be shared between Gaussian curve G(x) and a Lorentzian curve L(x); while with PsdVogit2, you can specify two distinct FWHM values wG for Gaussian curve G(x) and wL for Lorentzian curve L(x).

Sample Curve

PsdVoigt2.png

Parameters

Number: 6

Names: y0, xc, A, wG, wL, mu

Meanings: y0 = offset, xc = center, A =area, wG=Gaussian FWHM, wL=Lorentzian FWHM, mu = profile shape factor

Lower Bounds: wG > 0.0, wL > 0.0

Upper Bounds: none

Script Access

nlf_psdvoigt2(x,y0,xc,A,wG,wL,mu)

Function File

FITFUNC\PSDVGT2.FDF

Category

Spectroscopy