Views from aSmall: Specimen #2beta

Puzzler #1: If the diameter of the grid is 3[mm], what is it's thickness? Also what is the exact mesh of the grid (i.e. the number of lines per inch)? The manufacturer claimed that it was 200 mesh, but it might be fun to see how close that claim was to the truth. Also, how wide are the grid bars, and what fraction of the grid area is open, i.e. transparent to electrons.

Puzzler #2: Now take a close look at some of the holey carbon film. Can you determine the film thickness experimentally? How large are the holes in this film? What is an average diameter? What is the shape of the holes. Do they vary in size and shape? What is the standard deviation in size? What fraction of the holey film area is comprised of the holes themselves? What is the distribution of hole sizes, i.e. are the sizes normally distributed, does the distribution have multiple peaks, etc.?

Puzzler #3: Next, see if you can locate the enstatite lath. What are the lath's dimensions? What is it's shape? Is it faceted, or irregular in shape? If it has faces, what are the angles between them? What is the lath's volume and surface area?

Puzzler #4: Check out the solar flare tracks in the enstatite lath. Are the tracks randomly distributed, or is there evidence of a preferential orientation which might occur if the lath was buried near the surface of an object much larger than the range of solar flare tracks therein? How many tracks do you find in this grain? How many tracks per unit area was this grain exposed to? If you know that the lath was removed from a 10 micron interplanetary dust particle too small to shield it from track-forming solar flare particles, how much time spent at 1 AU (earth's orbit) around the sun would have been necessary to create the observed track density? What is the uncertainty in this exposure time due to counting statistics alone?

Puzzler #5: Take a close look at the exit and entry holes for the track in that part of the crystal which hangs over the edge of a hole in the carbon film. How has the previously flat surface been disturbed? Can you distinguish the entrance and exit holes? Do the rearranged atoms show signs of order, or disorder? What are the crater diameters, depths, and rim heights? How might one go about determining the ion mass, energy and direction from these surface features?

Puzzler #6: (NOT YET IMPLEMENTED) Decipher the hidden message (an extraterrestrial palimpsest ala Carl Sagan's Contact) buried in the unit-cell ordering of an interstellar silicon carbide grain.

Puzzler #7: (NOT YET IMPLEMENTED) Examine the structure of unlayered graphene in the core of a graphite onion formed in the atmosphere of a red giant star, for clues to precipitation processes in the cool atmosphere of such giant stars.

This is one of several web-based "active mnemonics", designed: (i) to offer complementary perspectives and resources for achieving present day teaching goals among students with a wide range of learning styles; (ii) to do this in the context of emergent topics in modern day science (e.g. nanoscale exploration, information physics, allpaths/action/aging and metric-based anyspeed dynamics), many of which have only begun to work their way into textbooks and curriculum goals; and (iii) to be reliably available for use by individual teachers in class and by students out of class. Nanoworld exploration is especially interesting in this regard since it can offer an open-ended challenge to one's skills at empirical observation and reporting, allowing students to "participate in scientific investigations based on real-life questions that progressively approximate good science". This is, for example, a primary goal of the K-12 Show-Me Standards on scientific inquiry, the basis for Missouri Assessment Program tests. Most classroom challenges instead focus on factual knowledge and skills at theoretical prediction, perhaps since robust empirical challenges have been more difficult to set up.

• The generic storyline for probing student skills and biases for empirical observation might go something like this: "Someone has just prepared a specimen for a closer look in your web microscope. You see it spinning in front of the robot's image when you move your mouse over the picture containing it. By dragging your mouse with a button down, you can rotate or even spin the specimen. By dragging the mouse vertically with the shift key pressed you can move in toward the rotation center for a closer look. Check out the specimen, and report back on what you are able to find out." This of course will not be specific enough for most students, or in fact most teachers. By that same token, with added specifics it might prove useful for students at various levels in topic areas ranging from materials microscopy to gestalt psychology. Revisiting the same model, with a new assignment in a different class, would also reinforce students' corollary awareness of the challenges faced in doing detective work at the nanoscale.
• Thermal physics and uncertainty: Fleas on fleas on fleas... (e.g. in a general studies course on the physical principles underlying "how things work"): "In this exercise at empirical discovery, you will be assessed on your ability to describe what you found and did not find, as well as on the quality of the data you managed to come back with. Basically, so far in this course we've talked of baseballs and tables and other macroscopic objects as just that: Individual objects. In fact, they are composed of tiny building blocks. A key parameter in thermal physics (e.g. the way temperature works) turns out to be uncertainty about the microscopic state of those building blocks. Since detective work on these nanoscales is increasingly important in fields ranging from engineering to medicine, this exercise gives you a feel for detective work on the state of atoms making up a small 3mm disk." Assignment: "Zoom in and around on the tiny disk that you'll find in this web microscope. Feel free to assume the disk diameter is 3mm, and to use the superposed grid to help estimate sizes of smaller things. The field-width estimator can also be used, although this might add additional uncertainty to your measurement. Then do the best you can to determine the spacing between gray atoms in the specimen's disk, a few of which are visible if you zoom in enough to see them. In the panel below then report: (i) your measured value, (ii) an estimate of your uncertainty in your measured value, and (iii) a description of the method you used to come up with it."
• Measuring Size Scales and Densities: Powers of 10... (e.g. as supplement to the opening "measurement" chapter of a standard introductory physics textbook): "Zoom down for a closer look at this 3mm diameter web specimen, to see if you can determine the distance between atoms in it, and/or the number of atoms it contains per cubic centimeter." You might be inclined to let them determine spacings on the superposed grids on their own. Alternatively, you might tell them to assume that the level 2 grid squares are about a micron across, and the level 5 squares about a nanometer across. Advantages to this exercise: It is an experimental challenge (something students often don't get outside of a lab), it offers a visceral feel for the large number of intervening worlds between that of humans and that of atoms, and it facilitates self-discovery about the nature of these concepts in a cutting-edge but practical setting frequented by today's nanoscale explorer.

• How do I measure distances? You can assume that the diameter of the disc is 3mm, and extrapolate all other dimensions from that. The superposed grid lines may be of qualitative, and in some cases quantitative, help. Serious detectives might also try to propagate uncertainties through the extrapolation as well. On the other hand, your teacher may tell you to start with different assumptions, e.g. the distance between atoms in a certain object. The "Estimate Field Width" button may also come in handy, although you might want to avoid taking the manufacturer's estimate blindly at face value. Quantitative comparisons are probably best done between objects whose distance from your vantage point is the same, and thus to set up may require some rotation and zooming on your part.
• How do I measure angles? In some cases the superposed grid lines, or other aspects of the geometry of objects, can be used to determine angles. Another trick for angles at the rotation point might be to note that you can spin an object at a constant rate of speed. If the spin takes you through the two directions of interest, the angle between them is simply 360 degrees multiplied by the time_between_directions divided by the rotation_period. Given that the beta applet also allows you to move the rotation center, in principle any two angles can be measured with arbitrary precision (e.g. using slower rotations) by this means. Lastly, the viewing direction is also roughly specified by values accessible from the Tilt and Rotation angle buttons. For those who enjoy spherical trigonometry, the angle between two different viewing angles (e.g. T1,R1 and T2,R2) is ArcCos[Cos[T1]Cos[T2]+Sin[T1]Sin[T2]Cos[R2-R1]].
• How do I record observations for later analysis, and reports? Although movies of what you see may be difficult to record, still photos of what you see on the screen should be possible to print out using File/Print (some browsers will let you select and print only the applet window), or capture as digital images using any of a number of screen capture utilities (e.g. Paint Shop Pro under Windows) or even with a camera. When saving an image, it's good practice to save relevant data (like field width at the rotation center) along with it. For example, you might append "w6p67n" to the filename of the image if the field width is 6.67 nanometers. When recording images on film, microscopists generally record useful information (along with the number of each negative) in a logbook. This is also recommended here, since not all information corollary to an image can be recorded in its filename. Note: Unlike magnification, field width and scale bar labels are not changed when the image is portrayed on larger or smaller screens. They also allow one to easily determine magnification e.g. by dividing field width into the width of the viewed image.

• Our first link page on variable size-scale adventures.
• More on research highlights and developing stories in our lab.
• Noom's notes on SPM and a virtual TEM interface to this model.
• Notes on a modular web/lab course for future users of nanomicroscopy data.
• Our Adobe Atmosphere anyspeed motion and web-lab simulators.
• Our ancient HTML-based microscope focus and astigmatism simulator.

• Push buttons to estimate the field width (now available), goniometer angles, and working distance.
• A couple of adenovirus particles and perhaps some other stray molecules, hidden elsewhere on the specimen.
• Ability to translate the rotation center in 3D, if desired with a dynamically-regenerated grid overlay and specimen to facilitate navigation plus offer non-trivial atom-scale detail throughout the specimen. This may seem like a modest task until one realizes that this specimen contains something akin to 10^20 atoms, i.e. around 10^12 gigabytes of information encoded in atom positions alone.
• Ability to pass observation parameters back into a calculation engine that can provide the explorer with HREM images, diffraction patterns, X-ray or roughness spectra, etc. of the field of view.

Live3D applet

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