Thanks, Pam and Jon for the clarifications. Again, does this approach take care of low angle peak asymmetry better? thanks,
nandini --- "Whitfield, Pamela" <[EMAIL PROTECTED]> wrote: > Nandini > > The best people to reply on behalf of fundamental > parameters would be Alan > Coehlo or Arnt Kern. > But until they do here goes.... > > The more general form is convolution-based profile > fitting. This can be > used for all peak profile types, whereas 'pure' > fundamental parameters has > only been inmplemented for the simple Bragg-Brentano > case (no > monochromators). Other geometries have to be > empirically modelled using a > standard and some sort of user-defined convolution > on top of the source > profile. Better fits can often be obtained using > this type of fitting than > the normal pseudo-Voigt or Pearson VII functions (in > my experience at > least). Where convolution-based fitting really > comes into its own in in > complex quantitative Rietveld analysis where the > number of refined variables > would become untenable for normal peak fitting. > Using convolution-based > fitting it is possible to cope with upwards of 10 > phases with severe peak > overlap and still get good results with good > stability. For example, > quantitative Rietveld analysis of cements is > becoming routine. > > Pam > > Dr Pamela Whitfield CChem MRSC > Energy Materials Group > Institute for Chemical Process and Environmental > Technology > Building M12 > National Research Council Canada > 1200 Montreal Road > Ottawa ON K1A 0R6 > CANADA > Tel: (613) 998 8462 Fax: (613) 991 2384 > Email: <mailto:[EMAIL PROTECTED]> > ICPET WWW: http://icpet-itpce.nrc-cnrc.gc.ca > > > -----Original Message----- > From: Nandini Devi Radhamonyamma > [mailto:[EMAIL PROTECTED] > Sent: June 4, 2004 6:42 AM > To: [EMAIL PROTECTED] > > > Dear All, > > > Is the fundamental parameter approach better than > mathematical approach used in most of the Rietveld > refinement programs? Does that mean programs which > use > that approach are better? Any suggestions? > > Nandini > > > > > __________________________________ > Do you Yahoo!? > Friends. Fun. Try the all-new Yahoo! Messenger. > http://messenger.yahoo.com/ __________________________________ Do you Yahoo!? Friends. Fun. Try the all-new Yahoo! Messenger. http://messenger.yahoo.com/
