Limitation of metallic sharpness from local electric field

[Loren Booda]

Since there is a significantly-above atomic limit to the allowed sharpness of an (approximately zero-dimensional) needle point due to its local electric field, would there be a similar limit to the keenness of an (approximately one-dimensional) razor edge?

 

[Astronuc]

Since there is a significantly-above atomic limit to the allowed sharpness of an (approximately zero-dimensional) needle point due to its local electric field, would there be a similar limit to the keenness of an (approximately one-dimensional) razor edge?

The limitations are related to materials and the geometry of tools used to make needles and razors.

The sharpest point would be a single atom, and this is only achieveable with atomic force microprobes. IBM scientists have done some amazing work with AFMs.

http://adsabs.harvard.edu/abs/1992SPIE.1556...79N

More generally -

http://www.iop.org/EJ/abstract/0960-1317/2/3/026

http://www.freepatentsonline.com/5611942.html

Unfortunately, I can't find a general paper or site that gives details on AFM's.

 

[Loren Booda]

Astronuc,

By "sharpness" I mean in terms of slimness, as in least solid angle for a needle. The probes you mention (granting the terminal atoms) are rather blunt nonetheless. My E-M professor once mentioned that the sharpness of metallic "spline" was limited (somewhat related to the effect of a lightning rod or comb teeth on a van de Graaff generator) by spontaneous fracture of its tip. So a needle, or spline, could only be so pointed, not from atomic considerations so much, but from the concentration of electric field in its above atomic scale tine.