September 22, 2000

"The Egg as Eye: Ultrananocrystalline Diamond in the Cosmos and in the Laboratory"
Dieter M. Gruen
Materials Science and Chemistry Divisions
Argonne National Laboratory

Synthesis of ultrananocrystalline diamond (UNCD) films has been accomplished in the laboratory making use of carbon dimer, C2, produced by fragmentation of C60. Interestingly, UNCD had been found in several primitive carbonaceous chondrites where it is the largest constituent of the presolar grain fraction in this class of meteorites. During the late stages of red giant stellar evolution, so-called planetary nebulae with lifetimes of ~ 104 years form. Although these objects have been known for over 200 years, their progenitors, called protoplanetary nebulae (PPNs) with lifetimes of ~ 103 years, were discovered only within the last 25 years. Many PPNs such as the Egg Nebula have intense C2 absorption bands. It is suggested that the synthesis of UNCD in the laboratory and in the cosmos proceeds on the basis of new growth and nucleation mechanisms involving the insertion of C2 into and carbon- hydrogen bonds. The carrier of the intense 21 µm emission is almost certainly a carbon containing material, and the possibility that UNCD is the carrier will be discussed. Carbon dimer, the small-est all-carbon molecule, is extremely reactive and can give rise to complex chemistries involving H, O, N, and other elements. The PPNs may, therefore, be viewed as cradles of chemistry providing insights into the earliest stages of cosmicchemical evolution.

Addenda to the Sept. SMSI meeting:
The Egg as Eye...Dieter M. Gruen

The meeting abstract is an excellent review of the talk. This time the recording secretary is only going to add notes to refresh the talk.

Sources cited in the talk are:

• Sara Russell & Conel Alexander. "Stardust" New Scientist 13 May 2000 pp.21-23.
• "Diamonds forged in long-dead stars are providing astronomers with sparkling insights into our origins," (A large Murchison meteorite with diamonds mentioned in this article is on display in the Field Museum)
• Gary Stix. "Micron Machinations," Scientific American, Nov. 1992. pp.106-117. According to Gruen, it deals with the first material for (mems) micro-electro-mechanical- systems: silicon has poor triboligical properties. It wears out and van der Waals & electrostaticforces cause stiction (vacuum weld) [ 33 hits on stiction and 234 hits on mems in Carl Uncover].
• On "Acta ephemerae et curiosa" (the Internet) the Hubble (PPNs) protoplanetary nebulae enhanced photos from the military site no longer are on the web. The new site is http://ad.usno.navy.mil/ord.html .
• Imaging of the Egg Nebula (CRL2688)-bb3. jpl.nasa.gov On this site that you must register.
• ASU-Noble Science and Engineering Library-PROTOPLANETARY AND PLANETARY NEBULAE, AND STELLAR EVOLUTION www.asu.edu
• Most recent hit on Carl Uncover by Dieter M. Gruen et al. "Theoretical Studies on Nanocrystalline Diamond. J.Phys. Chem. B, Vol.103, No 26 pp5459-5467, 1999.
• Post Script. see www.ses.swin.edu.au/research/highener.htm. Elias Siores, Head, School of Mechanical and Manufacturing Engineering, claims to have microwave vapor deposition of exhaust fumes from automobiles to produce diamonds on filters as a method to clean environmental air. Gruen is making diamond cantilevers and gears

Respectfully submitted, Stan Schmidt.