NetNotes
I used several years ago. Can anyone provide a detailed protocol for the preparation? Josif Mircheski
jmircheski@us.es Tu Jul 21 I usually just dump a bunch of sodium hydroxide pellets into a
glass Schott-style bottle and then add about 50–100 mL of ethanol to it. You want a saturated solution so if all the pellets dissolve, add more. You could use a stir bar to speed equilibration but I usually do it a couple of days beforehand and give the bottle a swirl once or twice a day and that is enough. It is obviously a caustic solution so be careful. Wear gloves and I usually require my students to wear safety glasses when using it. I simply carefully decant off the solution when I want to use it. Many anecdotal comments I have read on line over the years suggest it gets stronger the longer you let the solution sit. When I want to etch the sections, I use this procedure: (1) Pour about 40–50 mL of sodium ethoxide solution into a glass Coplin jar. Tis solution is very caustic—use gloves and eye protection! (2) Etch number and circle sections on the slides using a diamond pen. Rinse the slides with dH2O. (3) Carefully insert slides into the caustic sodium ethoxide solution using a forceps. Leave in etching solution for 1 hour. (4) Fill 3 Coplin jars with 95% ethanol, 70% ethanol, and dH2O. (5) Using a forceps, transfer the slides from the etching solution into the 95% ethanol for 10 min. (6) Using a forceps, transfer the slides from the 95% solution into the 70% ethanol for 10 min. (7) Using a forceps, transfer the slides to the distilled water Coplin jar. Transfer the Coplin jar to the sink and slowly run distilled water into the jar for 10 min. (8) Let the slides dry. Tom Phillips phillipst@
missouri.edu Tu Jul 21
Microscopy: errors in terminology Te latest Microscopy Today just bounced on my doorstep and
I have to say I am 100% with Charles Lyman’s editorial comment! And, whilst we are at it, what about destroying the other errors in understanding that have made their home in our subject? Most errors seem to crop up in SEM terminology. Take objective lens as a name for the third condenser, it does not follow microscopy parlance in that the does not produce the image, it simply acts as a third condenser. In truth it is the instrument’s electronics that produces the image. Ten there is depth of field when what people are talking about is depth of focus. How does the position of an imaging surface explain the way we visualize depth in an image? Please, please let us sort out depth of field and depth of focus too! Microscopy has an amazing history, so abusing names that were part of that history does seem so wrong! Steve Chapman
protrain@emcourses.com Fri Jul 22 I agree that the terms “depth of field” and “depth of focus” are
too frequently interchanged, but I feel that you, too, have fallen into the same trap. Tese two terms are well-documented and describe two quite different features in an imaging system. You got it correct in your 1986 book: Working with the Scanning Electron Microscope (page 22). Depth of field relates to the object space and depth of focus relates to the image space. Some microscopists use “depth of focus” when they really mean “depth of field”; the confusion seems to come from the fact that as the focus control is adjusted, different parts of the specimen (in the z-direction) go in and out of focus. So, when photographers (who first coined the terms) and light and electron microscopists use the term “depth of field” they are correct if they are talking about how much of the subject or specimen is in acceptable focus. Depth of focus is used to describe the how much a camera can be moved from the film /detector plane before the image becomes unacceptably out of focus. Depth of focus is usually a fixed distance that cannot be changed because it is unusual for the microscopist to be able to move the film or detector plane away from the imaging/
56
projection lens. For digital imaging in an SEM, depth of focus is a redundant term because there is no camera, so a microscopist shouldn’t even need to think about this term nowadays. Microscopy does have an amazing history and the two terms are well-established and easily understood, so any attempt to change their meaning will result in even more confusion. I hope that the depth of field and depth of focus is now sorted! Gary Nichols
gary.nichols@
pfizer.com Mon Jul 25 Tank you for pointing out a misunderstanding I may have
portrayed. When using the term “imaging surface” I was referring to the “film plane.” For those whom I may have confused, I think the TEM portrays depth of field and depth of focus very clearly. It is easy to see how small a depth of field the operator has (just microns) and it is clear the depth of focus is almost limitless with an image in focus on a digital camera both above and below the screen! Steve Chapman
protrain@emcourses.com Mon Jul 25 “Microns” of depth of field was a long time before aberration
correctors became popular. I think this discussion of depth of field will become more and more important as correctors allow larger convergence angles and subsequently severely reduce the depth of field. Furthermore the effect of sample thickness, convergence angle and also channeling will become more and more important especially due to the popular pass-time of analyzing at the atomic level directly down a zone-axis. In terms of systems with probe correctors, the depth of field goes to a number in the nanometer range. Well perhaps a few tens of nanometers. Jan Ringnalda jan.
ringnalda@fei.com Mon Jul 25 Tis is of course very interesting. But I have a totally different
experience that was and has been exasperating. Filing the Patent and Trademark Office Form VA for copyright registration of SEM, LM and TEM pictures, the application was rejected . . . . not once but several times. VA is visual arts—photographs. Well, the examiner rejected the application the first time because an image from a SEM or TEM was not a photograph. In his view, it was the product of a method of producing images and hence, was a patent issue. Sigh. Tere was no optical glass lens. Tere was no film (for SEM) but a negative for TEM. Te explanation I gave about how a TEM and SEM “images” were formed based on scanned or transmitted electrons did not connect with visual arts. Too technical of an explanation of how SEMs and TEMs work—oops. Electron optics was a deal killer. Re-submitted and hope to get a different person. Nope. OK. Change the submission title. Re-submit. Now waiting for several months. Patents are backed-up too as I hear. An objective lens made from copper wire? Tat did not fly. No shutter or flap mirror. No viewing prism. Registration denied. Finally, sanity should prevail. Gary Gaugler
gary@gaugler.com Wed Jul 27
Instrumentation: sputter coater I am attempting to remedy an issue with a Conductavac IV sputter
coater by SeeVac. Recently, it was observed that the ammeter needle was wavering considerably during the sputter coating process. Te needle would be at 0 mA and with a slight twist of the Current Adjust Knob the needle would be up near 40 mA (~ half way up ammeter). I assumed there might be a short somewhere in the system and aſter checking all the connections and making sure all junctions were snug no obvious problems were observed. Another sputter coating run was attempted but to no avail. However, the needle now moves with more fluidity. Control of the needle has been regained though the needle currently maxes out (100 mA) where the needle would typically be at 30 mA (proper amps for general sputter coating). Why the rapid increase in amps? I have also
www.microscopy-today.com • 2011 November
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76