[3dem] Ethane - propane mix

Bob Grassucci rg2502 at columbia.edu
Tue May 1 14:28:38 PDT 2012

On 5/1/2012 4:02 PM, William Rice wrote:
> Dear all,
> Have many of you had experience using a mix of 37% ethane / 63% 
> propane as a cryogen? It has the advantage that it stays liquid at 
> liquid nitrogen temperature. We had thought it would be easier to 
> handle, but we found that it seems to leave a thin layer of liquid 
> cryogen on the surface of the grid. Putting a freshly frozen grid into 
> the microscope seemed to cause problems with the IGP as this liquid 
> seemed to evaporate only in the high vacuum of the microscope. Solid 
> ethane frozen on the grid usually cracks and breaks off or sublimes in 
> the airlock during pumping before insertion. Has anyone else seen this 
> effect?
> Thanks,
> Bill
Hi Bill,
We saw the oil slick on our mixture as well but did not see the vacuum 
problem.  We did notice a great deal of high contrast dark blobs all 
over the grid we generally attribute to contaminants on the bottom of 
the ethane tank.  We were using a high purity ethane and a high purity 
propane but still got this effect.  We decided just to stick with the 

Howard Hughes Medical Institute
Columbia University Medical Center
Black Building Room 2-221
650 West 168th Street
New York, NY 10032-3702
rg2502 at columbia.edu
Phone: 212-305-9520
Fax: 212-305-9500

More information about the 3dem mailing list