EDX Upgrades Have an EDX system that's running out of steam? • New MCA and Windows based software from $4500. • Complete Electronics - Bias supply, premium 8th order triangular filter pulse processor, 4000 channel (0-20 keV at 5 eV per channel) MCA and full quantitative analysis software from $13,990. Visit our web site: www.ansxray.com for complete details and free demo software. /ANSI American Nuclear Systems, Inc. 1010 Commerce Park Dr., Suite G Oak Ridge, TN 37830 (800) 980-9284 FAX (423) 482-6253 email: sales@ansxray.com www.ansxray.com Value Through Innovation Lightning and the Electron Microscope Lydia Rivaud, Engelhard Corporation The chain of events that led to the invention of the electron microscope is an interesting story by itself. This chain has a common theme, namely electrons, and its first link is a natural phenomenon: lightning, A flash of lightning generates a stream of electrons with a potential energy difference of 100 to 200 megavolts between clouds acting as electrodes, Benjamin Franklin envisioned this as a source of energy and tried to snatch electricity from the skies, but this proved to be too dangerous, At the beginning of the century, lightning was a problem for electrical utilities because it produced surges that disrupted the steady flow of electric- ity along high tension lines. For this reason, in 1929 a high tension laboratory was founded in Germany with the sole aim of finding a way to test electrical transmission lines so as to make them capable of withstanding the lightning surges, The first approach to the problem was to design equipment that could simulate the effect of lightning on transmission lines. The test equipment already existed; cathode ray osciilographs, the precursors to modern commercial oscilloscopes, The cathode ray oscillograph used a beam of electrons in a high voltage chamber, a set-up similar to an electrical transmission line being affected by lightning's high voltage. There was a difference when comparing lightning and transmission lines to oscillographs with their voltage and electron beam. The osciiiograph could maintain a continuous high voltage on its electron beam, while lightning gives a series of voltage discharges on electrical lines lasting a fraction of a second each, The steady voltage in the oscillograph was more suiiable for experimenta- tion than a series of short voltage surges. In addition, the electron beam in the oscillograph could record any induced voltage disturbance affecting it by writing on a fluorescent screen. Cathode ray oscillographs constitute the second link in the chain of events being followed here. The next step was to modify the osciiiograph and its recording media in order to improve the resolution of the output signal recorded by the electron beam. The first modification was to pump the cathode tube chamber to a vacuum. The second modification was to improve the resolution of the electron beam by focusing it to a smaller spot. Max Knoll and Ernst Ruska in the German high tension laboratory then turned to Hans Busch's theory developed in 1929. Busch's theory postu- lated that a current circulating in a coil wrapped around a magnet had the same effect on a collimated beam of electrons as a glass convex lens on a light beam, Busch had, in effect, postulated the electromagnetic lens and Ruska decided to apply it to focusing the electron beam in the oscillograph in order to optimize its recording resolution on the fluorescent screen. The application of Busch's theory to the electron beam focusing in the oscillograph constitutes the third link in the chain of events that led to the invention of the electron microscope, Since Busch postulated that the electromagnetic lens should behave like a convex lens in an optical microscope, Ruska speculated he could apply the theory both to focus the electron beam in the oscillograph to improve the recording of voltage effects on the electron beam, as well as for constructing a magnifying microscope. He designed an arrangement of two electromagnetic lenses that would be capable of focusing the electron beam and in addition giving a magnified image of an object placed in front of the first lens. He placed the lenses in the vacuum inside the oscillograph chamber. Thus Ruska obtained a focused electron beam as well as the first electron microscope. The first three micrographs recorded were from bronze and platinum mesh grids at x4.3,x17.4, and x13 magnifications'. The electromagnetic lenses are the fourth link in the chain of events that started with lightning and led to the invention of the electron microscope, • 1. Martin M, Freundlich, "The History of The Development of The First High-Resolution Electron Microscope", MSA Bulletin, Vol.24, No.1 (1994). Circle Reader Inquiry #15 D o w n lo ad ed fro m h ttp s://w w w .cam b rid g e.o rg /co re . C arn eg ie M ello n U n iversity , o n 06 A p r 2021 at 02:04:50 , su b ject to th e C am b rid g e C o re term s o f u se, availab le at h ttp s://w w w .cam b rid g e.o rg /co re/term s . h ttp s://d o i.o rg /10.1017/S1551929500070358 http://crossmark.crossref.org/dialog?doi=10.1017/S1551929500070358&domain=pdf https://www.cambridge.org/core https://www.cambridge.org/core/terms https://doi.org/10.1017/S1551929500070358 Before Etching and Coating After Etching and Coating Before and after images showing the polished cross-^seclional view of a typical semiconductor device. The sample was etched for 5 minutes at 6 kv and coaled with Au/Pd. In the etched image, \hc detailed grain structure of" the tungsten plugs are plainly visible. PECS PRECISION ETCHING COATING SYSTEM Chemical-free etching and coating in a single unit for SEM and light microscopy The new Precision Etching Coating System (PECS™) provides clean, chemical-free etching and high resolu- tion sputter coating in one compact desktop unit. Chemical free etching. Eliminates hazardous chemicals from your lab and provides precise control over the etching process. Etching/coating in one instrument. Samples can be etched and coated without breaking vacuum, reduc- ing sample handling and contamination or oxidation. Controlled etching and coating. Rock and rotate angles and rocking speed can all be varied to ensure uni- form etching and coating of the sample. Increased sample throughput. Samples can be re- etched and coated as necessary. You can select up to four target materials without breaking vacuum. Dormant targets are fully shielded from sputter conta- mination. The 36-mm stage and sample holder will accept most SEM stubs and metallographic speci- mens. Easy to use With Simple controls. Programmable timer precisely controls the duration of sample etching or coating. Coating rates and thicknesses can lie mea- sured with probe and film-thickness monitor. For more information on the new PECS, contact Gatan or a Gatan representative for mare information. Gatan USA —Pleasanron, Ca tel 510 463 0200 fax 510 463 0204 Gatan USA —Warrendate Pa tel 412 776 5260 fax 412 776 3360 mbH, Germany tel (089)35 23 74 fas (089)35 51 642 Gatan Lrd, UK tel (01536) 743150 fax (01536) 743154 Circle Reader Inquiry #1 Gatan Services Corp., Japan td SI (3)3923 6752 fax 81 (3)3928 6758 Gatan Online www. ga tan. co m infa@gatan.com D o w n lo ad ed fro m h ttp s://w w w .cam b rid g e.o rg /co re . C arn eg ie M ello n U n iversity , o n 06 A p r 2021 at 02:04:50 , su b ject to th e C am b rid g e C o re term s o f u se, availab le at h ttp s://w w w .cam b rid g e.o rg /co re/term s . h ttp s://d o i.o rg /10.1017/S1551929500070358 https://www.cambridge.org/core https://www.cambridge.org/core/terms https://doi.org/10.1017/S1551929500070358