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No. 76: Jul-Aug 1991

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New Insights As To The Structure Of Matter

Possible 'nuclear-molecular' forms of magnesium-24 and carbon-12
Possible "nuclear-molecular" forms of magnesium-24 and carbon-12.
Inside the atom. Physicists have long visualized the atomic nucleus as being a shell-like arrangement of its constituent protons and neutrons. Tantalizing experiments suggest other wise. Magnes ium-24, for example, may under some circumstances exist as two carbon-12 nuclei in tight orbit, as in the illustra tion. Even more startling is the "sausage" form of magnesium-24, in which six helium-4 nuclei (alpha particles) are lined up in a row. This "hyperdeformed" state has not yet been detected in the lab, but it demonstrates new thinking among the physicists. (Kenward, Michael; "Are Atoms Composed of Molecules?" New Scientist, p. 21, April 6, 1991.)

Comment. Evidently we do not know everything about nuclear physics.

Beyond the molecule. We are used to seeing atoms and molecules arranging themselves into mathematically regular crystals. Now it appears that particles consisting of thousands of atoms also spontaneously organize themselves.

A.S. Edelstein et al find that molybdenum particles assemble themselves in cubes with two prominent edge lengths: 4.8 and 17.5 nanometers. The larger cubes show up in micrographs as 3x3x3 groupings of the smaller cubes. The smaller cubes each contain about 7000 atoms. (Edelstein, A.S., et al; "Self Arrangement of Molybdenum Particles into Cubes," Science, 251:1590, 1991.)

Comment. What are the "organizing forces" here? Why cubes? Why the heirarchy of cubes? Why 3x3x3 super cubes?

From Science Frontiers #76, JUL-AUG 1991. � 1991-2000 William R. Corliss