Some Research Highlights, and Developing Stories

with help from the UM-StL Center for Nano Science
Microscope Image and Spectroscopy Tech Lab

[DigitalDark] [StarSmoke] [NanoBump] [FringePatterns] [Surprisal] [NanoSleuth] [AnySpeed]

Description Story
Digital darkfield detective work (blurb started here May 2003)

ico-twin butterfly
reciprocal nanocone

Papers on tableaus and picometer differences for Microscopy and Microanalysis 2006 in Chicago IL.

Digital darkfield decompositions: Manfred Rühle Interfaces Symposium, August 2004 Microscopy and Microanalysis, Savannah GA. [slides]

More detailed eprint.

Researchers in the UM-StL Scanned Tip and Electron Image Lab have expanded on digital versions of optical darkfield strategies (similar to looking for dust on a mirror face-on while shining a strong light from the side), with simple but not widely known mathematical connections to the wavelet analysis used for compressing images. These are being applied to lattice images of technologically-interesting materials from across the region, taken with the Missouri's only atomic (two Ångstroms point-to-point) resolution electron microscope.
This digital darkfield detective work helps researchers at industries and universities across the region to find and identify hidden structures in images (e.g. twinning in metal nanocrystals, or reaction rims on catalysts), as well as to map atom position deviations as small as a hundreth of an atom across. These deviation maps in turn allow "strain-mapping" as illustrated here, below an image of white tunnels between atom columns in a cross-section of wafer silicon on silicon-germanium under development by industry for the next generation of smaller and faster computer chips.

Starsmoke nano-cones photographed at UM-StL (Ap J Lett 578 L153-156, 2002) as continuation of the long-standing role of St. Louis researchers in the laboratory study of dust from around our star and other stars

Paper on presolar atom-sheet bending for Microscopy and Microanalysis 2006.

Slides on materials astronomy

Astrobiology provides realtime feedback on the evolution of stars and planets like our own. One source of this information on the changing world around us is the collection of tiny astrophysical objects (space dust) which has made its way to earth for study in sophisticated ground-based labs. For example, thanks to ion probe studies done in the past couple of decades at Washington University's McDonnell Center for Space Sciences, we now have first hand evidence that the carbon atoms inside you were manufactured in red giant stars spread out across the Milky Way throughout the first five billion years of our galaxy's lifetime.

Now researchers only 15 minutes away at the University of Missouri-StL have obtained pictures of carbon atom sheets whose arrival in our solar system was concurrent with the carbon atoms in you, but which remain bonded to sibling atoms that made the trip across the galaxy with them from the star in which they were born. In other words, we now have pictures of molecules like those in which your carbon atoms made their interstellar voyage to earth.
These observations, made with a high resolution electron microscope at UM-StL and reported in the astrophysics community's journal for rapid publication, indicate that much of the carbon on earth traveled here in the form of high-purity unlayered graphene. This is the stuff of which buckyballs and single-walled carbon nanotubes are made, and a material not reported to occur naturally in high purity elsewhere. Although man has only in recent years begun figuring how to create single-walled carbon nano-structures of abundance, it appears now that red giants used such a process to bring solidify freshly-made carbon atoms before sending them off with the help of starlight to form new stars, planets, and eventually life. Moreover, the wide cone angles which connect the atom-thick sheets together in the low density carbon of these specimens suggest that the process by which they were formed is different from any known on earth. Circumstantial evidence suggests dendritic solidification of droplets of liquid carbon from erupting jets originating deep in the star.

Spontaneously-formed nano-pits in air-exposed silicon for gigascale integrated-circuits (ESSL v5 n9 G83-G85, 2002), as continuation of the long-standing role of Missouri researchers in silicon science and technology UM-StL researchers have reported, and are continuing to study, tiny defects that form spontaneously at room temperature on silicon surfaces prepared by a variety of methods but which have so far been possible to ignore by the electronic device industry because of their small size and weak strain fields. Experiments with researchers at MEMC Electronic Materials in O'Fallon Missouri on the trapping of impurities in gigascale integrated circuit silicon (computer chips) during device manufacture created the need for this study, because the size of trapping defects in the silicon interior has now moved down into the 10 nm (50 atoms on a side) range. Looking for such small objects required that researchers at UM-StL take a closer look at "pesky nanodots" that had been showing up in electron microscope images of thin silicon specimens for years.
A breakthrough came when Iris Mack, an exchange student from Stuttgart, discovered that "running down the hall after thinning a specimen" to put it into the electron microscope not only suppressed defect formation, but allowed microscopists to thereafter observe the spontaneous formation of these defects in real time. The results were reported in ESSL, the rapid publication journal of The Electrochemical Society. Researchers here suspect that these defects in effect harden the surface of air-exposed silicon much like the formation of a film on cooling but unstirred soup, and hence may prove to be worthy allies or adversaries as computer chip line-widths move into the nanometer range. Current work is focussing on the possible role of transition metals in their formation.

Fingerprinting nanocrystals from lattice images at two tilts (Ultramicroscopy v94 n3-4 245-262, 2003)

More on visibility maps and making sense of lattice fringes now available in: J. Appl. Phys. 98 (2005) 114308 and the vJournal of Nanoscale Sci & Tech 12 (2005).

Some interactive fringe visibility and Kikuchi maps.

Additional papers for aberration-corrected microscopy meetings, and other stuff on digital interferometry, are linked here.

Notes on covariance profiling.

This paper considers how nano-humans might determine the 3D structure of crystals, if they were able to re-orient the crystal in their hand while trying to peer down along tunnels between the columns of atoms which run in various directions. If you could see these tunnels, you could formulate rules for folks to use in recognizing a face-centered cubic crystal, a body-centered cubic crystal, etc. Precisely this type of manipulation (imagine a hand which can only tilt the crystal through a limited angle, over one or two fixed axes) is becoming possible with modern day million-dollar atomic resolution transmission electron microscopes.

To illustrate, click below to rotate the silicon nanosphere at left over the 35.3 degrees separating the four-fold symmetric <001> zone from the two-fold <112> zone in two steps: 20 degrees over a vertical (e.g. stage-tilt) axis, followed by 30 degrees over a horizontal (e.g. goniometer) axis. The second button reverses the sequence.
Lattice planes visible edge-on, before and after, allow unambiguous identification of the crystal's diamond-fcc lattice. You can also freely turn the model with the mouse. Which orientation do you like best? A more detailed version of the model is here.
According to Ultramicroscopy, a journal of cutting-edge microscopy technique, researchers here in collaboration with Wentao Qin (a UM-StL Ph.D. graduate hired by Motorola's Digital DNA Lab in Mesa Arizona) have managed to do the above analysis experimentally with the St. Louis microscope, on tungsten carbide nanocrystals provided by researchers from the Graduate Center for Materials Research at UM-Rolla. Work is continuing now on expanding these analytical strategies with computer-support for nano-detectives equipped with the aberration-corrected electron microscopes of the future.
Thermal roots of correlation-based complexity (blurb started here May 2003)

Tales of a cool device, bogeyman code, plus multiscale time and values.

Notes on layered niche-networks for the May 2006 Understanding Complexity meeting at UIUC. Notes and paper from a talk at the 2005 meeting.

"Net surprisals ala Tribus: correlations from reversible thermalization" (poster/MS for ICCS 2004 in Quincy MA, May 2004).

"Heat capacity in bits" in Amer J Phys 71, 11 (2003) 1142-1151 in the long-standing tradition of Missouri researchers (including E. T. Jaynes) applying gambling theory to physical systems.

AAPT summer 2003 talk notes.

How about courses with few prereqs on everyday inventions, or informatics?
The physical role of uncertainty about the state of a system in its environment has become increasingly apparent since work by Claude Shannon on noise in communication lines in the late 1940's. It has guided error-correction in phone communications, the development of data-compression methods (e.g. ZIP and GIF files on your computer), and the development of tools for tracking the evolution of information in genetic codes (e.g. mitochondrial DNA) as well as ideas (see the article on chain letters in the June 2003 issue of Scientific American). Now it's moving into areas relevant to the future of computers, and provides a common physical framework for considering such disparate issues as energy conservation, maintenance of genetic diversity within and between species, idea dynamics, and the future of cultural diversity in the face of increasingly rapid means for communication and transportation.
In a paper for AJP, the most prestigous but also least understandable physics education journal, researchers at UM-StL examined how these developments impact our understanding of simpler things e.g. why temperature is a useful concept, or how the heat capacity of water changes as it cools from gas to liquid to solid form. In the process, one discovers that temperature is a measure of the energy needed to decrease the mutual information about a system of molecules by one bit, and heat capacity measures the number of bits of information lost per two-fold increase in temperature. Although these insights are unlikely to affect the way weather is reported on the morning news anytime soon, they are already providing insight for students into the physical laws that underlie complex systems ranging from lasers, through computers, to human communities. One set of connections in this regard is illustrated below...

Observations related to more complex systems include new prospects for use of physical boundaries (like a cell membrane or the edges of a gene pool) to systematically inventory correlations associated with the natural history of invention. Among other things, multiscale thinking like this indicates that humans have evolved to support only five of the six niche levels currently available to them, and that insight into the dynamics of idea codes that interact with these levels may be crucial to solving present day as well as future problems.
Nano-detective challenges for students in web-connected classes (blurb started here Aug 2004).

St. Louis Science Cyberville splash screen for our Oct 2005 nanoday, links for a 2006 book chapter on nanoed, an intro-chem nanochallenge, and a web journal for peer reviewing empirical observation reports.

Some interactive...

A web/lab course in nanoscale science practicals

Savannah 2004 poster

Recent NSF proposal summary

Some variable size scale adventure links.

AAPT crackerbarrel on deep simplifications

Nano-exploration can serve up a rich source of modern-day inquiry-based empirical observation challenges to science students at all levels, if their classes have some form of access to the world-wide web. We are therefore working to develop resources accessible to teachers at the grass-roots level, to bring figures in existing textbooks to life with content-modernizing opportunities for student exploration, reporting, and peer review which make use of real-world data and problem-solving techniques whenever possible.

Metric-based approaches to anyspeed motion empower students and explode myths (blurb started here Jun 2003)

"Live remote" spacetime explorer and artificial gravity laboratories for data acquisition by students in web-connected classrooms.

Note on introducing mechanics metric-smart from day one.

An anyspeed acceleration applet.

Storylines for use of these tools in existing courses.

Many of our notes for teachers are archived in citable form. The collection single-frame views of spacetime is an exception.

Roadmap to content modernization on this site.

Which of the following is fact and not fiction? "When traveling from point A to B, objects travel over all possible paths at once provided they are not being watched." "Wristwatch time passes more quickly for a couch potato, since from a map-frame's perspective we travel at lightspeed through time only when we're not traveling through space." "Absent external forces, traveling objects tend to follow paths from A to B that result in the maximum amount of aging during the course of the trip." "Practical consequences of these arcane facts (to your everyday life) already exist and will increase in days ahead." If any of these assertions sound ridiculous to you, then you have some pleasant surprises to look forward to since nature is indeed stranger than most of us can imagine. Moreover, insight into this strangeness is becoming easier thanks to recent followup work on "deep simplifications" first offered by Richard Feynman and Hermann Minkowski in the first half of the last century. In particular...
Allpaths/Action/Aging approaches to introducing the quantum-mechanical causes of motion (even in curved spacetime) under development for introductory classes, e.g. by E. F. Taylor at MIT, are complemented by map-based (single-frame metric-based) "anyspeed" descriptions of motion being refined at UM-StL. One element of these approaches is to "maximize insight while minimizing misconceptions" from the beginning. The work at UM-StL, using Minkowski's spacetime version of Pythagoras' theorem to define anyspeed variables and rules (referenced to a coordinate-grid and clocks co-moving with a selected "map-frame"), shows students with few to no prerequisites how:
  • to predict readings on clocks traveling at any speed with respect to the map frame, in comparison to the reading on nearby map-frame clocks;
  • to track constant acceleration at any speed, as well as how the finite speed of light (strangely enough) expands possibilities for travelers wishing to travel hundreds or thousands of map-distance lightyears in ten years of time on their own wristwatches; and
  • force and Newton's laws remain useful but frame dependent, not only at any speed but also locally on accelerated and curved-spacetime maps with help from "affine-connection forces" (like gravity) that act on every ounce of an object's being.
*Connections without an external source citation, and ones listed as "in press", represent stories in development but not necessarily in stand-alone form. Hence you should contact the investigators involved before passing the story along.
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