CCP14
Dear all, Sorry for any inconvenience regarding ccp14 going down for a few hours, it required a spot of immediate maintenance. Please be aware we are bringing on line the new primary server and would like to warn you of this just in case ccp14 goes down again. Kind regards William Bisson -- William Bisson Davy Faraday Research Laboratory The Royal Institution of Great Britain 21 Albemarle Street London W1S 4BS Tel: +44 (0)20 7670 2977 (Direct) Tel: +44 (0)20 7409 2992 (Switchboard) Fax +44 (0)20 7670 2958 Http://www.ri.ac.uk/DFRL/ The RI is a registered charity (number 227938)
Dummy histograms
Dear all, I am having issues trying to get RAWPLOT to plot a dummy histogram. I created from scratch an exp file, input a dummy histogram using a parameter file for the D20 at the ILL. I have input all my atoms. The scale factor is set to large (1) and all refinement flags are off. For some reason every time I want to generate a powder pattern for a particular wavelength I end up with this error. It is irrelevant what scan numbers are input, on the second time of asking for a scan number it crashes? I will be grateful if someone can tell me the best method to display a dummy histogram. Many thanks William -- William Bisson Davy Faraday Research Laboratory The Royal Institution of Great Britain 21 Albemarle Street London W1S 4BS Tel: +44 (0)20 7670 2977 (Direct) Tel: +44 (0)20 7409 2992 (Switchboard) Fax +44 (0)20 7670 2958 Http://www.ri.ac.uk/DFRL/ The RI is a registered charity (number 227938)
Re: Diffractometer problem
Dear Apu, I am still unable to se the image. May be the mailing list strips out images. I don`t know. Can you send me the image direct to my email address [EMAIL PROTECTED] What geometry is the D8 in? What is the radiation and what elements is contained in your sample? Regards Will On 14 Sep 2006, at 19:18, [EMAIL PROTECTED] wrote: Dear Will, This is the figure: Regards, Apu /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Apu Sarkar Research Scholar Variable Energy Cyclotron Centre 1/AF Bidhan Nagar Kolkata 700 064 INDIA phone: 91-33-2337-1230 (extn. 3190) Fax: 91-33-2334-6871 /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ - Original Message - From: [EMAIL PROTECTED] Date: Thursday, September 14, 2006 10:59 pm Subject: Re: Diffractometer problem > Dear Apu, > > I didn't see any attached spectra, but I'm guessing having used > the D8 > that what you are seeing is an increase in intensity as you go > from > low angle <10 2theta to above. This occurs in the Bragg-Bretano > setup > because of the lip from the magnetic holder that keeps the sample > plate in position, cutting out intensity at low angle. > > Regards > Will > > Quoting [EMAIL PROTECTED]: > > > Dear All, > > We are using a Bruker D8 Advance diffractometer. Recently we are > > > facing a problem with the diffractometer. During a scan, > suddennly > > there is a jump in the intensity (please see the attached > figure). > > After that the background becomes high. > > > > Can any one suggest how to get rid of this problem!! > > > > Regards, > > Apu > > > > > > > > > > > -- William Bisson Davy Faraday Research Laboratory The Royal Institution of Great Britain 21 Albemarle Street London W1S 4BS Tel: +44 (0)20 7670 2977 (Direct) Tel: +44 (0)20 7409 2992 (Switchboard) Fax +44 (0)20 7670 2958 Http://www.ri.ac.uk/DFRL/ The RI is a registered charity (number 227938)
Re: how to find Polarization
Dear Larry, When you removed the soller slits leading to increased the axial divergence, which profile function is appropriate to model this, especially at low angle where the asymmetry is very stark? Kind regards William On 30 May 2006, at 16:01, Larry Finger wrote: [EMAIL PROTECTED] wrote: Dear All, if I well understood JFC correction is perfect in case of parallel incident beam; so, in case of conventional Bragg-Brentano diffractometer, shouldn't it work well only in case of use of Goebel Mirrors, that get incident beam exactly parallel? And is it true that using Goebel Mirrors and sample in capillary (Debye-Scherrer) gets intensity values more realistic than on a conventional Bragg-Brentano geometry? Thanks in advance, marco Not really. The FCJ correction (note the authorship please) was derived for the parallel incident beam case, but it works for divergent optics. The main difference is that for the parallel beam case, one can measure the slit sizes perpendicular to the plane formed by the incident and diffracted beams, directly calculate the values for S/L and H/L, and get values very close to the "best-fit" results. For divergent beam optics, the "effective" width is greater than the apparent width. As discussed earlier in this list, in the divergent beam case, a set of 0.02 (radian) slits will yield refined values of 0.027 for S/L and H/L, not 0.02 as predicted from the geometry. In the extreme case, I removed the Soller slits on my conventional B-B diffractometer, and could still fit the resulting profiles, which were greatly affected by axial divergence. As I recall, S/L and H/L were on the order of 0.2! BTW, the intensities were increased by roughly a factor of 10. I had to cut the tube power to avoid saturating the detector. Putting your sample in a capillary avoids a lot of sample problems that occur with a flat plate; however I'm not sure that I would make the blanket statement that you do. That topic should be addressed by someone with experience with mirrors. Larry -- William Bisson Davy Faraday Research Laboratory The Royal Institution of Great Britain 21 Albemarle Street London W1S 4BS Tel: +44 (0)20 7670 2977 (Direct) Tel: +44 (0)20 7409 2992 (Switchboard) Fax +44 (0)20 7670 2958 Http://www.ri.ac.uk/DFRL/ The RI is a registered charity (number 227938)
