[3dem] reflections from gold fiducials

Lars-Anders Carlson lars-anders.carlson at umu.se
Mon Nov 6 13:13:14 PST 2017


Dear community,
We encountered something during tilt series acquisition recently that I 
hadn't seen before: several 10 nm gold fiducials gave clear reflections, 
see attached image (compressed snapshot - it looks stronger in the 
original images).

The reflections were often symmetrically arranged around a fiducial and 
would then disappear at the next tilt ange. We used a 100 um objective 
aperture at a Krios at 300kV. Admittedly I never worried about the 
crystalline arrangement of gold fiducials before, so I took some higher 
mag images of the fiducials, and some of them look mosaic, others more 
monocrystalline (see image), which could explain why some cause more 
reflections than others.

Is this something people have encountered before? Are some batches of 
fiducials better ordered than others at the atomic level? I'm curious to 
hear what people think of this since it fascinated me...

Cheers,
Lars

-- 
Lars-Anders Carlson
Assistant Professor
Dept of Medical Biochemistry and Biophysics
Wallenberg Centre for Molecular Medicine
Umeå University
901 87 Umeå, Sweden

lab website including OPEN POSITIONS:
http://www.carlsonlab.se/
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