Dear All, In this scenario, which should be the number for LP in Topas if ones has a D8 with a primary monochromator for pure CuKalpha1?
thanks for the response, angel l. ortiz > > Dear Peter, > > Of course the LP correction can't be sample-dependent and for your > configuration LP=0 should be Ok for all samples. It seems that you have an > intensity loss at high-angles that may be partly compensated by LP=90. > Possible reason may be in a misalignment of the anti-scattering slits or > screen (knife) if you use them. > > Best regards, > Leonid > > ******************************************************* > Leonid A. Solovyov > Institute of Chemistry and Chemical Technology > 660049, K. Marx 42, Krasnoyarsk , Russia > www.icct.ru/eng/content/persons/Sol_LA > www.geocities.com/l_solovyov > ******************************************************* > > --- On Thu, 7/23/09, Peter Y. Zavalij <pzava...@umd.edu> wrote: > > From: Peter Y. Zavalij <pzava...@umd.edu> > Subject: RE: LP factor in the Rietveld refinement > To: rietveld_l@ill.fr > Date: Thursday, July 23, 2009, 4:52 AM > > Well... the situation with LP is not so simple. Using TOPAS for refinement > data collected on D8 advance with Ni-filter and LynxEye detector I observe > the following: > - For all samples LP=0 is OK and gives the best fit as it should be by the > book. > - HOWEVER for LaB6 standard LP=0 yields very poor fit for several high > angle > reflections (>120 deg. 2theta) while LP=90 gives perfect fit. The > difference > in R factors 12% and 4% cannot be simply ignored... > > Can anyone explain this? > > > Peter Zavalij > > X-ray Crystallographic Center > University of Maryland > College Park, MD > > Office: (301)405-1861 > Lab: (301)405-3230 > Fax: (301)314-9121 > > > > >
