The discussion focuses on the peak profile fitting in X-ray crystallography, specifically the use of the Voigt function, which combines Gaussian and Lorentzian profiles. Participants explore the physical reasons behind the Gaussian and Lorentzian components and inquire about the skewness of the peaks.
Participants present multiple competing views regarding the physical origins of the Gaussian and Lorentzian components, and the discussion remains unresolved regarding the skewness of the peaks.
Limitations include the lack of detailed exploration into the specific mechanisms causing skewness and the dependence on definitions of broadening types.
C_Pu said:Hi,I've been doing a lab cycle on X-ray crystallography. We are using Cu X-ray source on chloride salt crystals. It seems that the Bragg peak profile are commonly acknowledged to be a Voigt function, which is a convolution of Gaussian and Lorentzian. I am wondering what's the physical reason for this. What causes the Gaussian spread and what leads to the Lorentzian component?
And is there an explanation for skewness of the peaks?Andy Resnick said:Gassian lineshapes are due to inhomogeneous broadening mechanisms (Doppler, local strain, etc), while Lorentzian are due to homogeneous broadening mechanisms (collisions, pressure broadening etc).
C_Pu said:And is there an explanation for skewness of the peaks?