Reinhard is right that it is best to improve the instrument to produce cleaner data. I'm concerned about the advice to model all kinds of features whose origin is not fully understood, simply to obtain a better fit. Shay has told us nothing about his instrument or his conditions of data collection. He asks "Is it a sample preparation problem", to which the obvious reply is "Do you see this with other samples or different materials" ? Only he can answer that. If the answer is yes, he might try modifying his instrument (remove filters etc) to see what effect that has on the pattern from a simple well characterised material. Again only he can do that. Data collection is an experimental science, and data refinement should not be reduced to a "black box" computer program where extra parameters can be added to reduce the R-factor. Alan.
On Mon, 4 Sept 2023 at 08:18, Reinhard Kleeberg < kleeb...@mineral.tu-freiberg.de> wrote: > Can be modeled in the BGMN peak profile model as well, by modifying > the *.lam file by a series of additional Lorentzians on the 1/lambda > scale, see figure. > The same can be done for other spectral impurities, e.g. W L > satellites. Also "electronic effects" on the wavelength distribution > profile like the "edges" from the ROI settings of Si drift detectors > can be modelled in such a convolution based approach. > However, better to have a pure/simple wavelength distribution (clear > alpha1/2 doublet) by a monochromator or high energy resolution > detector, as any satellites make trouble in trace phase analysis and > do cause prolonged calculation time in complicated Rietveld refinements. > > Reinhard > > > > Zitat von Matthew Rowles <rowle...@gmail.com>: > > > Topas can model them quite well. The functionality was introduced in > > version 5. > > > > On Mon, 4 Sep 2023, 00:54 Kurt Leinenweber, <ku...@asu.edu> wrote: > > > >> Hi, Are these things modeled in Rietveld programs, by chance? It seems > >> like a lot of baggage to put in a refinement but if it makes the results > >> better… > >> > >> > >> > >> - Kurt > >> > >> > >> > >> *From:* rietveld_l-requ...@ill.fr <rietveld_l-requ...@ill.fr> *On > Behalf > >> Of *Thomas Gegan > >> *Sent:* Sunday, September 3, 2023 9:16 AM > >> *To:* Bish, David L <b...@indiana.edu>; Shay Tirosh <stiro...@gmail.com > >; > >> Fernando Igoa <fer.igoa.1...@gmail.com> > >> *Cc:* Rietveld List (rietveld_l@ill.fr) <rietveld_l@ill.fr> > >> *Subject:* RE: [EXT] Re: [External] Re: Step-like basline > >> > >> > >> > >> I agree with a Ni absorption edge, possibly with a Kβ peak around 38° > 2θ. > >> > >> > >> > >> *Tom Gegan* > >> Chemist III > >> > >> > >> > >> Phone: +1 732 205-5111, Email: tom.ge...@basf.com > >> Postal Address: BASF Corporation, , 25 Middlesex Essex Turnpike, 08830 > >> Iselin, United States > >> > >> > >> > >> *From:* rietveld_l-requ...@ill.fr <rietveld_l-requ...@ill.fr> *On > Behalf > >> Of *Bish, David L > >> *Sent:* Sunday, September 3, 2023 7:08 AM > >> *To:* Shay Tirosh <stiro...@gmail.com>; Fernando Igoa < > >> fer.igoa.1...@gmail.com> > >> *Cc:* Rietveld List (rietveld_l@ill.fr) <rietveld_l@ill.fr> > >> *Subject:* [EXT] Re: [External] Re: Step-like basline > >> > >> > >> > >> Some people who received this message don't often get email from > >> b...@indiana.edu. Learn why this is important > >> < > https://urldefense.com/v3/__https:/aka.ms/LearnAboutSenderIdentification__;!!IKRxdwAv5BmarQ!fFhSHn4S5iEzkW-O9lvWG-OzoqK_2SKhRniGa71nxuOL3GcxiyD83i2mnNN0Z48HPkn4zjKqH-aqqA$ > > > >> > >> Hello Shay, > >> > >> I think it is probably related to "tube tails". You can read about this > in > >> the literature (e.g., on the BGMN web site) and you can model it in some > >> Rietveld software such as Topas. You don't normally notice this but it > >> becomes apparent with higher-intensity peaks. > >> > >> > >> > >> Regards, > >> > >> Dave > >> ------------------------------ > >> > >> *From:* rietveld_l-requ...@ill.fr <rietveld_l-requ...@ill.fr> on behalf > >> of Fernando Igoa <fer.igoa.1...@gmail.com> > >> *Sent:* Sunday, September 3, 2023 3:06 AM > >> *To:* Shay Tirosh <stiro...@gmail.com> > >> *Cc:* Rietveld List (rietveld_l@ill.fr) <rietveld_l@ill.fr> > >> *Subject:* [External] Re: Step-like basline > >> > >> > >> > >> This message was sent from a non-IU address. Please exercise caution > when > >> clicking links or opening attachments from external sources. > >> > >> > >> > >> Hey Shay, > >> > >> > >> > >> Are you using a motorized slit during the measurement? These may open up > >> abruptly to compensate for the angular dependence of the footprint and > thus > >> generate an abrupt increase in the intensity. > >> > >> > >> > >> Hope it helps :) > >> > >> > >> > >> On Sun, Sep 3, 2023, 8:50 AM Shay Tirosh <stiro...@gmail.com> wrote: > >> > >> Dear Rietvelders > >> > >> I am attaching a zoom-in on a diffraction profile. > >> > >> My question is what is the origin of the step-like profile next to a > very > >> large reflection peak? > >> > >> Is it a sample preparation problem? > >> > >> Is it part of the baseline? > >> > >> Thanks > >> > >> Shay > >> > >> -- > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> > >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> Please do NOT attach files to the whole list > <alan.he...@neutronoptics.com > >> > > >> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body > >> text > >> The Rietveld_L list archive is on > >> http://www.mail-archive.com/rietveld_l@ill.fr/ > >> < > https://urldefense.com/v3/__http:/www.mail-archive.com/rietveld_l@ill.fr/__;!!IKRxdwAv5BmarQ!fFhSHn4S5iEzkW-O9lvWG-OzoqK_2SKhRniGa71nxuOL3GcxiyD83i2mnNN0Z48HPkn4zjJTf8rNHg$ > > > >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> > >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> Please do NOT attach files to the whole list > <alan.he...@neutronoptics.com > >> > > >> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body > >> text > >> The Rietveld_L list archive is on > >> http://www.mail-archive.com/rietveld_l@ill.fr/ > >> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > >> > >> > > > -- > TU Bergakademie Freiberg > Dr. R. Kleeberg > Mineralogisches Labor > Brennhausgasse 14 > D-09596 Freiberg > > Tel. ++49 (0) 3731-39-3244 > Fax. ++49 (0) 3731-39-3129 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Please do NOT attach files to the whole list <alan.he...@neutronoptics.com > > > Send commands to <lists...@ill.fr> eg: HELP as the subject with no body > text > The Rietveld_L list archive is on > http://www.mail-archive.com/rietveld_l@ill.fr/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > -- ______________________________________________ Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE <alan.he...@neutronoptics.com> +33.476.98.41.68 http://www.NeutronOptics.com/hewat <http://www.neutronoptics.com/hewat> ______________________________________________
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <alan.he...@neutronoptics.com> Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
