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Mark et al.<br>
<br>
I agree with Tom Laue (but not always :-) )<br>
<br>
This is almost certainly the result of using quartz windows. We use
only sapphire windows - for all optics. And I have many very old
windows that are clear to the far UV. We have taken spectra of them
and have them all cataloged so we know whihc are good for UV and which
no so good.<br>
<br>
Above a certain speed, the fringes will fade out or become blurry and
you will see jumps in the fringe display on the XL-I - as you have seen.<br>
<br>
I do not exceed a laser duration of 1.4 degrees when using the old
interference window holders (which I recommend that everybody use -
unless you are also taking absorbance scans.)<br>
<br>
and I typically use 0.4 degrees when using the absorbance window
holders.<br>
<br>
Could you show us screen dump of the fringe pattern from the upper
window?<br>
<br>
Walter<br>
-- <br>
<pre class="moz-signature" cols="72">
===============================================
Walter F. Stafford, Ph.D.
Senior Scientist
Boston Biomedical Research Institute
64 Grove Street
Watertown, MA 02472
617-658-7808
skype: w.stafford3
----------------------
"Be kind, for everyone you meet is fighting a hard battle." -Plato
------------------------------------ </pre>
<br>
Mark Agacan wrote:
<blockquote cite="mid:4D666239020000240005D0CB@ia-gw-6.dundee.ac.uk"
type="cite">
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<div>I checked the laser settings as advised and found:</div>
<div> </div>
<div> </div>
<table border="1" cols="4">
<tbody>
<tr>
<td width="50"><br>
cell</td>
<td width="50"><br>
laser delay</td>
<td width="50"><br>
laser duration</td>
<td width="50"><br>
exposure time</td>
</tr>
<tr>
<td width="50">2</td>
<td width="50">157.1 deg<br>
</td>
<td width="50"><br>
1.7 deg</td>
<td width="50">6.30 uS<br>
</td>
</tr>
<tr>
<td width="50">
<div>4<br>
</div>
</td>
<td width="50">67.1 deg<br>
</td>
<td width="50">0.6 deg<br>
</td>
<td width="50">2.22 uS<br>
</td>
</tr>
<tr>
<td width="50">6<br>
</td>
<td width="50">337.6 deg<br>
</td>
<td width="50">1.7 deg<br>
</td>
<td width="50">6.3 uS<br>
</td>
</tr>
</tbody>
</table>
<div> </div>
<div>I also found this in the rasmb archives:</div>
<div> </div>
<div>"<span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;">The
main "gotcha" about setting the duration is that if you go too high you<br>
will end up with the superposition of a single-slit interference
pattern upon the<br>
double-slit interference pattern. As long as you use the typical <strong>0.5
- 0.8<br>
degrees for the duration</strong> (assuming that you are NOT using the
old style interference<br>
window holders) you will be fine."</span></div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"></span> </div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"><font
face="Tahoma" size="2">So I'm thinking to bring the laser duration
for cell2 and cell6 down to the value of cell4. Any further advice is
greatly appreciated.</font></span></div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"></span> </div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"><font
face="Tahoma" size="2">Many Thanks,</font></span></div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"></span> </div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"><font
face="Tahoma" size="2">Mark</font></span></div>
<div><span class="Apple-style-span"
style="word-spacing: 0px; font-family: 'Times New Roman'; font-style: normal; font-variant: normal; font-weight: normal; font-size: medium; line-height: normal; font-size-adjust: none; font-stretch: normal; -x-system-font: none; text-transform: none; color: rgb(0, 0, 0); text-indent: 0px; white-space: normal; letter-spacing: normal; border-collapse: separate; orphans: 2; widows: 2;"></span> </div>
<div> </div>
<div> </div>
<div> </div>
<div>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
Dr Mark Agacan, Scientific Officer for the Division of Biological
Chemistry and Drug Discovery,<br>
Wellcome Trust Biocentre, College of Life Sciences, University of
Dundee, Dundee, DD1 5EH <br>
Tel: +44 1382 386095 Fax: +44 1382 345764 Mobile: 07525 451 117<br>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</div>
<div> </div>
<div>
<div>************************************************************ </div>
<div>
<div><font color="#666666">Please consider the environment. Do you
really need to print this email?</font> </div>
</div>
<br>
<br>
>>> Tom Laue <a class="moz-txt-link-rfc2396E" href="mailto:Tom.Laue@unh.edu"><Tom.Laue@unh.edu></a> 2/24/2011 13:05
>>><br>
Hi Mark-<br>
The interference system requires the use of sapphire windows, except at
<br>
very low rotor speeds.<br>
Modern synthetic sapphire windows may be used to 230 nm. The old <br>
sapphire windows were not clear much past 280 nm, but that is no longer
<br>
an issue.<br>
I know that some labs have switched to using only sapphire window since
<br>
they almost never break, and may be used with all three optical systems.<br>
Best wishes,<br>
Tom<br>
<br>
On 2/24/2011 4:37 AM, Mark Agacan wrote:<br>
> Hello,<br>
> I have attached a jpeg image showing recent SV interference data
plots <br>
> taken from sedfit.<br>
> All data was collected with quartz windows as I was primarily <br>
> interested in the absorbance @ 280 nm signal.<br>
> IP2 and IP6 are very noisy but IP4 looks fine.<br>
> Is this a calibration problem or is this related to damaged
windows / <br>
> centerpieces (there are no visible defects or scratches on any of
the <br>
> components).<br>
> Many Thanks,<br>
> Mark<br>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
> Dr Mark Agacan, Scientific Officer for the Division of Biological <br>
> Chemistry and Drug Discovery,<br>
> Wellcome Trust Biocentre, College of Life Sciences, University of <br>
> Dundee, Dundee, DD1 5EH<br>
> Tel: +44 1382 386095 Fax: +44 1382 345764 Mobile: 07525 451
117<br>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>
> ************************************************************<br>
> Please consider the environment. Do you really need to print this
email?<br>
><br>
> The University of Dundee is a registered Scottish charity, No:
SC015096<br>
><br>
><br>
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-- <br>
Department of Biochemistry and Molecular Biology<br>
University of New Hampshire<br>
Durham, NH 03824-3544<br>
Phone: 603-862-2459<br>
FAX: 603-862-0031<br>
E-mail: <a class="moz-txt-link-abbreviated" href="mailto:Tom.Laue@unh.edu">Tom.Laue@unh.edu</a><br>
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