[3dem] Contamination rates

[Mike Strauss]

Hi Ruben,

I have checked with our engineer and these are the house measurements  
for our contamination rates:

Jeol 3000 SFF:  at 4K (Helium cooled) we have a contamination rate of  
0.4-0.6 nm/hour for the 1st hour, and about 1.5 nm / hour after 4  
hours.  But the predominant contaminant here (as previously mentioned)  
is nitrogen.

Polara G2:  < 0.3 nm/hour at liquid nitrogen temperatures.  We haven't  
used the Polara's helium temperature capabilities for data collection  
since our Jeol is more efficient in helium usage.

Tecnai 12 equipped with an anti-contaminator box:  0.7nm/hour

CM120 equipped with blade anti-contaminators: ~1nm/hour in the 1st  
hour, and increases after this.

I'm afraid I can't offer any information concerning Jeol microscopes  
operated at nitrogen temperatures.

Best Regards,
mike


On 12-Nov-08, at 5:56 PM, Ruben Diaz-Avalos wrote:

> Hello everyone,
>
> I am quite interested in knowing if people have carried out  
> measurements of contamination rates for different microscopes, and  
> what are the results of their measurements, to find out how the  
> different instruments fare in this test. At the NYSBC we have both  
> JEOL and FEI instruments, and we measure significantly different  
> contamination rates between the two brands, therefore I would like  
> to know if we are observing a common trend.
>
> By contamination rate in this case, I mean the rate of accumulation  
> of water on the grid's surface per hour (in nanometers per hour). A  
> low contamination rate obviously is very desirable, since only then  
> a sample can be used for a long session of data collection.
>
> Cheers!
>
> Ruben.
>
> ********************************************
>
> Ruben Diaz-Avalos, Ph.D.,
> Technical Director,
> New York Structural Biology Center,
> 89 Convent Ave. at 133rd St.,
> New York, NY 10027
> tel: (212)939-0660 x 529
> cell:(646)300-1453
>
> ********************************************
> _______________________________________________
> 3dem mailing list
> 3dem at ncmir.ucsd.edu
> https://mail.ncmir.ucsd.edu/mailman/listinfo/3dem