provocative opinion A Suggestion for a Convenient New SI Prefix Cherylann Schieber Agricultural Research, Rohm and Haas Company, Spring House, PA 19477 Frederick R. Longo Drexel University, Philadelphia, PA 19104 The angstrom unit (A or 8) is a convenient unit in many branches of science. On this basis, and on the basis of the great scientific contributions of Anders Jonas Angstrom, we wish to present an argument to elevate a term derived from his name to the status of an SI prefix. Anders Jonas Angstrom was born to a lumber mill chaplain on 13 August 1814 in Logdo, Bruk, Sweden. At the age of 25, after receiving his PhD in physics from the University of Uppsala, he joined the faculty and devoted his entire career to studv. teachine. -. and research in the areas of nhvsics. astronomy, and spectroscopy.' In the course of his iesearch h g s t r o m develo~edmethods for the measurement of absolute wavelength'and absolute light intensity; he thereby made spectroscopy a quantitative science. In 1868, using a diffraction grating, Angstrom published the map of the solar spectrum, giving the absolute wavelengths of approximately 1000 lines. Until Angstrom's work, line positions were given in terms of various arbitrary scales; hereported the wavelength in units of 10-'Om, which in 1905 was officially named the angstrom unit. He also developed the most celebrated of pyrheliometers, instruments devised to measure absolute light in tens it^.^ The heart of his pyrheliometer consisted of two identical strips of blackened platinum. One was irradiated while the temperature of the second was increased by passage of a measured electric current. The electrical energy required to hring the second strip to the temperature of the irradiated one was thus equal to the radiant energy absorbed. Hence Angstrom was instrumental in developing apparatus to measure absolute wavelength and absolute intensity and thereby vastly increased the power of the spectroscopic method. In 1862 he reported the spectrographicdetection of hydrogen in the Sun, and soon thereafter he discovered the pres-
1030
Journal of Chemical Education
ence of other elements. Angstrom was elected to the Royal Society in 1870 and received the Rumford Medal in 1872. His work was of Nobel quality but, of course, this prize was initiated after his era, and he did not receive it. I t is not necessary to argue the convenience of the Angstrom unit in chemistry, physics, molecular biology, etc., but this unit does not fit the formalism of the Systeme Internationale, which defines the units and prefixes to be used in quantitative scientific discussions. T o take advantage of this convenience we therefore propose the use of the derived term, angstro, as a prefix meaning one-ten-billionth, 10-'0. Furthermore, although it is not extremely important, we wish to point out that the prefix, angstro, in combination with the terms for various SI units, produces a phonetically acceptable name; for example, there is no awkwardness in angstrometer, 10-lo m; angstrogram, 10-lo g; angstromol, 10-lo mol, etc. In summary, we propose angstro as an SI prefix in order to honor a distinguished scientist and to hring into common, systematicusage a prefix that for the discussion of molecular science and some areas of spectroscopy is more appropriate and convenient than nano or pico. We also suggest that the abbreviation for the prefix angstro continue to he one of the currently used abbreviations for the angstrom unit that is, A or 8; hence angstrometer would be abbreviated as Am or i m , angstromol would he Am01 or Qmol,etc.
'
Asimov, Isaac. Asimov's Biographical Encyclopedia of Science and Technology: Avon: New York, 1976 Biography No. 484. Houston, R. A. A Treatise on Light Longmans, Green: New York. 1921.
