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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:blue'>Igor, that empty cell scan looks good to me. Could you send us a radial intensity scan of a cell containing something with an OD in the range of 0.5 to 1? Also are you using an 8-hole or 4-hole rotor?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:blue'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:blue'>John<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:blue'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> RASMB [mailto:rasmb-bounces@list.rasmb.org] <b>On Behalf Of </b>Igor Perevyazko<br><b>Sent:</b> Friday, February 20, 2015 8:05 AM<br><b>To:</b> Borries Demeler; andrew.leech@york.ac.uk<br><b>Cc:</b> RASMB List<br><b>Subject:</b> Re: [RASMB] XLI absorbance problem<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><div><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>Dear Andrew, dear Boris<o:p></o:p></p></div><p class=MsoNormal>Thank you very much for your suggestions! <o:p></o:p></p></div><p class=MsoNormal>Well, the interference optics works fine on the same cell and as can be seen by eye the magnetic dot on the stripped ring seems to be ok. At the moment I have only tried the same cell and monochromator on the working XLI<o:p></o:p></p></div><p class=MsoNormal>Regarding the Borris's points:<o:p></o:p></p></div><p class=MsoNormal>I have performed the intensity scan with an empty cell in the hole and the radial position is in the normal range (left on 5.8 and right on 7.15), so the radial calibration seems to be ok. The thing is that as you can see on graph 2, I have also checked the intensity of reference (benzene) and the sample sector filled with dye solution (Pyrene) and it has practically the same intensity level as if I scan an empty cell. As I see it, if there was a delay problem the intensity of a cell filled with a solution must be close to 0 then, if I understand your concern correctly. I have also attached the radial intensity scan for a cell (no windows).<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>Best regards<o:p></o:p></p></div><p class=MsoNormal>Igor<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>On Fri, Feb 20, 2015 at 6:31 PM, Borries Demeler <<a href="mailto:demeler@biochem.uthscsa.edu" target="_blank">demeler@biochem.uthscsa.edu</a>> wrote:<o:p></o:p></p><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal style='margin-bottom:12.0pt'>Dear Igor,<br>I agree with Andrew, this looks like a timing problem, obviously when<br>you intensity scan an empty hole it doesn't have this problem (no septum,<br>cell components in the light path) so the timing being a little bit off<br>still lets it hit the hole, just not a 2.5 degree channel. Can you still<br>perform an intensity scan when you put an empty cell in the hole? I am<br>not sure what the radial position was. If the radial calibration is off<br>you may not be at the position you think you are, so radially scan an empty<br>cell or the counterbalance and make sure the edges are at reasonable positions.<br><br>-b.<br><br>On Fri, Feb 20, 2015 at 04:20:53PM +0300, Igor Perevyazko wrote:<br>> Dear RASMB members,<br>><br>><br>><br>> We are having a problem with absorbance optics on XLI centrifuge(XLI_1 on<br>> the images attached). Hopefully you can suggest something that will<br>> help. The problem is that optical density of any samples (which definitely<br>> absorb, including for example BSA (c = 4mg/mL) or pyrene dye (c = 10<span style='font-family:"Calibri",sans-serif'>然</span> ))<br>> recorded by the AUC is within the zero level. Nevertheless, at much higher<br>> concentrations (approximately 10 -20 times higher) the optical density<br>> reaches some level of absorbance (~0.1-0.2 OD). The same solutions checked<br>> by normal UV-Vis spectrophotometer and on another XLI centrifuge (XLI_2),<br>> have adequate values of the absorbance level. We have as well checked our<br>> monochromator on XLI_2 and it was working ok. Recorded lamp intensities<br>> (air to air) at 230 nm and 530 nm are at the normal level. If we perform<br>> the absorbance scan of a sample (for example Pyrene dye at c = 10<span style='font-family:"Calibri",sans-serif'>然</span>) in<br><span class=im>> the intensity mode, we received the same level of intensities for both</span><br><span class=im>> reference and sample chamber! The corresponding comparison of the</span><br><span class=im>> intensities is shown on the image attached. Any of your suggestions about</span><br><span class=im>> the possible problem and/or the solution will be highly appreciated.</span><br><span class=im>></span><br><span class=im>></span><br><span class=im>> Best regards</span><br><span class=im>></span><br><span class=im>> Igor Perevyazko</span><br><span class=im>></span><br><span class=im>></span><br><span class=im>> PhD Igor Perevyazko</span><br><span class=im>> Physics Department, Polymer Physics</span><br><span class=im>> St.Petersburg State University</span><br><span class=im>> Ul. Ulyanovskaya 1, Petrodvorets</span><br><span class=im>> St.Petersburg, Russia, 198504</span><br><span class=im>> Tel.: (812)4284382</span><br><span class=im>> Fax.: (812)4287240</span><br><br><o:p></o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>> _______________________________________________<br>> RASMB mailing list<br>> <a href="mailto:RASMB@list.rasmb.org">RASMB@list.rasmb.org</a><br>> <a href="http://list.rasmb.org/listinfo.cgi/rasmb-rasmb.org" target="_blank">http://list.rasmb.org/listinfo.cgi/rasmb-rasmb.org</a><o:p></o:p></p></div></div></blockquote></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>