Radio age research, manufacturing, communications, broadcasting, television (1941)

DEVICE IDENTIFIES ATOMS Electron Micrc-aimlyzer Deoehped by Dr. Hillier in RCA Laboratories Reveals Chemical Composition of Ultra-microscopic Matter. IDENTIFICATION of atoms in ultra-microscopic particles of matter no larger than 1/100,000 of an inch in diameter can be accom- plished quickly and accurately for the first time by a revolutionary new tool of science—the electron Tnicro-analyzer — developed experi- mentally by Dr. James Hillier of RCA Laboratories. Revealed by Dr. Hillier in a letter published in the current issue of the magazine Physical Review, the new instrument — like the RCA Electron Microscope-—promises to go far toward overcoming one of the great barriers to the accumu- lation of knowledge about the infini- tesimally small particles of matter of which all things are made. In- formation vital to the solution of many practical problems in the physical, chemical, and biological sciences, according to Dr. Hillier, can be obtained. "The chemical elements constitut- ing such unimaginably tiny objects as the head or tail of a bacterium or virus," he said in an interview today, "can be identified within a few minutes by this new instru- ment." Supplementing the electron mi- croscope, the micro-analyzer comes ever closer to observing the build- ing blocks of nature, Dr. Hillier ex- plained. Scientists in recent years have been turning up invaluable in- formation as to the size, shape, and internal structure of microscopic particles of matter, and now they can identify the atoms of which they are made. "The vital question: "Of what particular atoms, or chemical ele- ments, are these different particles of matter constructed?' can be an- swered by the electron micro-analy- zer," he continued. "For the first time, the scientist, using this new instrument, will be able to deter- mine the chemical constituents of a particle weighing only 10"^^, or 1/1,000,000,000,000,000, grams. And, more imi)ortant still, he will be able to see the relationship of the particles to the rest of the speci- men under examination." In operation, the micro-analyzer uses an "electron needle" of ex- traordinary fine focus to knock other electrons loose from their parent atoms in the specimen, meas- ures the amount rf energy lost by Iili. JAMES HILI.IKK (LEFT) ANDDK. V. K. ZWORYKIN DEMONSTRATE THE NEW ELECTRON MICRO-ANALYZER. DR. HIL- LIER PREPARES TO INSERT A SPECIMEN, WHILE DR. ZWORYKIN HOLDS THE PHO- TOGRAPHIC PLATE. tile incident electrons in the proc- ess, and thereby reveals the speci- men's chemical content. "With the new instrument, the image of the specimen may be ob- served by means of an electron mi- croscope, which is incorporated as a part of the micro-analyzer, and a selection made by the exact portion to be analyzed," Dr. Hillier said. "Then by manipulation of a few controls, a photographic exposure is made of what we call the 'elec- tron velocity distribution.' "This results in a series of small marks on the photographic plate, each one of which indicates by its position the presence of a chemical element in the specimen. Thus, with one exposure, information is ob- tained that would have required weeks or months to obtain by pres- ent indirect methods, which too often result in failure." In explaining how the instrument works. Dr. Hillier pointed out that in the table of chemical elements each atom, or element, is differen- tiated from another by the number of electrons surrounding the atom's nucleus. The electrons are arranged around the nucleus in "shells," he added, and it is known how much energy, or voltage, is required to knock holes in the shells of different atoms. "In the micro-analyzer," he con- tinued, "the electi'ons of the 'needle' that strike the selected area of the specimen are all moving with the same velocity, say 50,000 volts. After they have passed through the specimen area, some of the elec- trons—the ones that struck atoms —are traveling with less velocity, or energy. "The next thing of importance in micro-analysis is the fact that the energy loss suffered by the speed- ing electron is different for each chemical elements. What's more, the differences are large enough to be easily distinguished by a method of measuring electron velocities. If, [RADIO AGE 13]