NPACI EnVision Article: A Tradition Flowers: The Maria Goeppert Mayer Interdisciplinary Symposium at SDSC
(from the SDSC/NPACI archives: http://www.npaci.edu/envision/v17.2/flowers.html)

From the Broad and General to the Deep and Specific: The Sixth Annual Maria Goeppert Mayer Symposium
(from the SDSC archives: http://www.npaci.edu/online/v5.6/mgm.html)

UNIVERSITY OF CALIFORNIA, SAN DIEGO -- The sixth annual symposium in honor of Nobelist Maria Goeppert Mayer was held at UCSD on March 3. It was organized by Kim K. Baldridge of SDSC/UCSD and Tammy Dwyer of the University of San Diego,
This year's MGM Symposium (as it has been called) featured five major speakers. Each talk began with a rather broad and sweeping question: How did life arise on this planet and perhaps others? Could there be somewhere in the universe where new matter is being created? Can organic molecules function to extend the properties of semiconductor chips? What are the prospects for nanomachinery since Richard Feynman first imagined them in 1983? Uniting the seemingly disparate topics was the way in which each scientist went from the broad and general to the fine-grained and specific matter of each talk.

"I think it was a particularly fitting tribute to the memory of Maria Mayer," said UCSD chemist Marjorie Caserio, "because her own contributions ranged from the very general--the nuclear shell model--to the quite specific, like the two-photon emission in beta decay and the electronic structure of benzene."

About 150 people attended the symposium, whose sponsors included the American Chemical Society, the National Biomedical Computational Resource, Pfizer Incorporated, SDSC, and UCSD. The talks were followed by a poster session showing work of students and postdoctoral fellows at various universities and research institutions (mostly in California, but also including Canada's McMasters University). The award for best poster went to Julie Mitchell, a postdoctoral researcher in bioinformatics at SDSC (in the group of Lynn Ten Eyck), whose poster concerned her development of a rapid computational method of analyzing shape complementarity in protein-protein complexes. Eric Elliott (Chemistry, UCSD) and Stacey Brydges (McMasters University) were runners-up.

Kim Baldridge noted that, now that the annual symposium is well established, she and other organizers have applied for additional funding from the National Science Foundation. "With that," she said, "we have every expectation of being able to present more ambitious programs next year and in the future."

Life on Other Planets?
The first speaker, who was introduced by Caserio, was Winifred M. Huo. Huo is Chief of the Computational Chemistry Branch at NASA's Ames Research Center in northern California, where she is also a researcher in the NASA Center for Computational Astrobiology. She noted that she had been lucky enough to meet Maria Goeppert Mayer when both worked at Argonne National Laboratory, Mayer as a visiting scientist and Huo as a graduate student. Huo's own research has focused on atomic, molecular, and optical physics, with emphasis on collisional and ionization phenomena, multiphoton processes, and computational physics. These interests coalesce in recent studies by Huo and her group of questions in astrobiology.

The age-old question of the possibility of life on other planets has attracted more interest recently because of studies indicating that Mars may have sequestered more water than previously thought. In addition, astronomers have been adding to the collection of extrasolar planetary formations. Particularly exciting has been the discovery of subglacial lakes in Antarctica that may harbor microbes and the possibility that similar lakes or oceans may exist beneath the ice of three Jovian moons, Ganymede, Callisto, and Europa. In preparation for a NASA mission to Europa, Huo and her group have been carrying out simulations of the chemical effects of impacts from bolides (large meteors) or comets on the surface of a planet.

What organic molecules might come from such impacts? The question depends on both the contents of the comet or meteor and the composition of the receiving atmosphere of the planet. In her simulations, Huo found nothing prebiotic in the debris of an impact on a normal, Earth-like atmosphere. But in a reducing atmosphere, the shock chemistry can produce interesting products, like acetylene, within nanoseconds after impact. Huo's team was able to simulate the rapid dissociation occurring on impact, which was computationally intensive owing to the small timesteps involved. "It had been believed that the dissociation took place over the whole time of impact, yielding only elemental products," Huo said, "but we have shown that this is not right. In fact, the shock products retain the history of their origin, and their rapid dissociation and recombination may indeed leave prebiotic molecules on planetary surfaces."

Newly Created Matter?
Margaret Burbidge, UCSD astrophysicist and Professor Emerita, was introduced by Valentina Molteni of DuPont Pharmaceuticals. Burbidge received her doctorate from the University of London and worked at the Yerkes Observatory and the California Institute of Technology before joining the UCSD faculty in 1962. She has been at UCSD since then, except for a stint as Director of the Royal Greenwich Observatory (1972-1974), and she was the founder and first director of the UCSD Center for Astrophysics and Space Sciences. In 1977, she was the first female president of the American Astronomical Society, and she was elected to the National Academy of Sciences in 1978. She also served as president of the American Association for the Advancement of Science (1982).

Burbidge is well known for the elucidation, with Geoffrey R. Burbidge, Sir Fred Hoyle, and the late William A. Fowler, of the way in which elements heavier than hydrogen and helium are produced by nuclear reactions in stellar interiors. Hoyle and the Burbidges are also well known for contesting the standard cosmological theory that all matter was created in the Big Bang, and they have been seeking evidence that new matter may be created by energetic processes occurring throughout the universe, in particular within active galactic nuclei. Margaret Burbidge has worked recently with Halton (Chip) Arp of the Max Planck Institute (Munich) and other colleagues to examine data on such galaxies, and she reported on their progress to date.

The group has surveyed a number of small, faint X-ray sources found just beyond the active galaxies that "are suggestive of bipolar ejecta" from those galaxies. The objects are quasars; at optical wavelengths, they are very faint (20th magnitude) blue objects. Burbidge has examined optical spectra from such objects around NGC4258 and NGC2639, galaxies for which X-ray satellite data are also available. The group then compiled a list of similar high-redshift sources found near the active nuclei of Seyfert spiral galaxies. They also found an unusually dense group of sources around NGC1068 and Arp220 (a galaxy with a possible double nucleus, first catalogued by Arp). At the end of March, Burbidge has telescope time at the Lick Observatory (near Santa Cruz), during which she hopes to obtain the spectra of faint quasars around the object M82.

If new matter is being created in active galactic nuclei and thrown into space in the form of energetic quasars, the spectra of such objects may be clues to the nature of the process and may exhibit significant differences, for example in elemental abundances, from current cosmological estimates.

New Talents for Semiconductors?
Stacey F. Bent, assistant professor of chemical engineering and electrical engineering at Stanford University, was introduced by Patricia Fagan, a postdoctoral researcher at The Scripps Research Institute. Bent obtained her doctorate at Stanford in 1992 and taught at New York University for several years before joining the Stanford faculty. She was the recipient of a National Science Foundation CAREER award in 1995 and of the Beckman Young Investigator award in 1997. In 1998, she was named a Camille Dreyfus Teacher-Scholar and a Research Corporation Cottrell Scholar, and she was the recipient last year of the Peter Mark Memorial Award of the American Vacuum Society.

Bent and her group at Stanford are attempting to develop a molecular-level understanding of the complex chemical reactions that are involved in the processing of electronic materials. They are also interested in extending the uses of such materials by various means, including, for example, the attachment of monolayers of organic compounds to semiconductor surfaces. Possible applications for such compound semiconductors exist in nonlinear optics, sensor technology, next-generation nanodevices, and atomic-scale lithography, among others--to say nothing of the potential direct benefits of "organic semiconductors" through as-yet-unexploited reactions. The field is essentially new, and Bent and her collaborators have been in the position of developing both the methods of attaching organics to semiconductor surfaces and the variety of diagnostic instrumentation needed to verify the results. Elements of Stacey Bent's research program.

Bent uses silicon, germanium, and diamond surfaces, attaching organic molecules to them by means of chemical vapor deposition and similar "dry" processes. First with alkenes and conjugated dienes (two-ended molecules joined by carbon double bonds) and then with more complex amines, carbonyl compounds, and amides, the group has studied the chemistry of the bonding reactions and the subsequent orientation/conformation of parts of the molecules that may be available for further reactions. Spectroscopies of various kinds revealed the dominance, in all these preparations, of a particular type of cycloaddition reaction (Diels-Alder) that leads to stable bonding of the organic to the Group IV surface (Si, Ge, or C). Bent concluded, "our group is now building a tool chest for designing reactions leading to selective and controlled, monolayer-by-monolayer growth in vacuum of organics on semiconductors."

Building the Nanoworld
The next speaker, Roya Maboudian, associate professor of chemical engineering at UC Berkeley, was introduced by Francesca Marassi of The Burnham Institute. Maboudian obtained a doctorate in Applied Physics from the California Institute of Technology and worked at Penn State University and UC Santa Barbara before joining the Berkeley faculty in 1993. She received an NSF Young Investigator award in 1994, a Beckman Young Investigator award in 1996, and both a Department of Energy Early Career award and a Presidential Early Career award in 1998.

Maboudian and her group are interested in surface and interfacial phenomena (adhesion, friction) in microelectromechanical (MEM) and nanoelectromechanical (NEM) machinery, technologies in which the fabrication techniques appropriate to integrated circuitry are used to make miniature mechanical components (beams, membranes, valves, pumps, gears). Her talk at the MGM Symposium was a detailed exploration of this territory, using as counterpoint a video of a talk called "There's Room at the Bottom," given by Richard Feynman in 1983. Feynman had conceived of nanomachinery as long ago as 1960, and it was still a gleam in his (and not many others') eyes when he gave his talk. Feynman anticipated many of the uses to which micro- and nanotechnology are being put today: photonics, microengines, micro-instrumentation, communications, robotics, and transportation (e.g., computer and micromachinery controlling fuel injection or airbag deployment). He was fascinated by the potential of a regime in which surface and interfacial forces are much greater than external forces upon a body--one in which adhesion, friction, and wear are deadlier than accelerations.

Maboudian's group has studied the effect, in such regimes, of "stiction," which appears as a result of capillary, electrostatic, van der Waals, and chemical forces. These are problems that can be reduced by surface roughening, the application of hydrophobic films or organic coatings, and other measures to produce the desired mechanical characteristics. She showed a film of nanomachinery designed by her group in collaboration with scientists at Sandia National Laboratories in which a gear-drive is operating at 300,000 rpm after treatment to reduce both initial and in-use adhesion. Maboudian foresaw a flowering of new technologies as the concrete expression of Feynman's dreams fused with the work of applied physics.

And Off to the Stars…
The final speaker was UCSD physicist and NASA astronaut Sally Ride, who was introduced by Jeannie Arruda of Merck, the pharmaceutical firm. Ride's talk focused not on her current work in physics but on the work she has been doing to bring young people (and girls especially) into the orbit of the space effort. She has just formed a company, Imaginary Minds, to pursue new educational projects. Ride emphasized that, over the course of the space program, nearly 30 women have flown in space. Currently, a fourth of the astronaut corps is female. She showed many slides illustrating what it is (and is not) possible to view from the Space Shuttle, emphasizing the opportunities the program has given scientists to obtain global intuition about the state of the planet. One girl in the audience summarized the talk very succinctly when she said, "Sally put the world in our hands."