DUNN Associates, Inc. - Analytical Chemistry (ACS Publications)

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DUNN

Associates, Inc. P.O. Box 2047 Silver Spring, Md. 20942 Telephone: (301) 942-2127 Circle No. 105 on Readers' Service Card 84 A

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ANALYTICAL CHEMISTRY

INSTRUMENTATION

Werner Centennial

2536.519 A but has to be wary of V, Fe, Rli, Bi, P, Ta. Indeed, a P t line only 1/20 the intensity of the Hg line has a wavelength of 2536.49 Â. The other neighbors differ by only 1 or 2 tenths of an Â. Anyone who wishes to plug these values into Ve — hv can note the minute potential differences in V associated with these transitions. Also, the Auger electrons representing a nonradiating transition are unique because the resources of optical spectroscopy are fruitless. Our interest and present excitement over the recent developments goes back to more than 40 years. Our postdoctoral studies at the Institute of the late James Franck at Gottingen were at a time when he was concerned with other important problems and hardly liked to be reminded of the simple but epochmaking experiment which he and Gustav Hertz had made in 1914. I n bombarding mercury vapor with electrons of controlled velocity, they had noted the inelastic impact at 4.9 volts and properly identified as the excitation energy leading to the emission of the first resonance line of Hg at 2537 À. This was the first experimental demonstration of the validity of quantized energy levels in the atom as postulated by Bohr a year earlier. Although Franck and Hertz jointly and singly determined many other critical impact values, the subject soon became of great interest and, in the hands of Bergen Davis, Foote, Mohler, and K. T. Compton, was soon established as a firm relationship between electrical excitation and optically established energy values, leaving no apparent extensions of further profit. It soon became accepted that real precision was to be gained from the spectroscopic data and not from electrical measurements. The superb achievements of modern spectroscopy from the X-ray region out to microwaves can well be regarded as a fait accompli. What more could be asked for certainty and precision? We have continued to ask, and bore our friends, with the question, "What more can be learned electrically about flames, arcs, sparks, and luminous gases?" The unquestioned advantage of optical methods may be put bluntly, "Seeing is believing." To do these things electrically is obviously doing it the hard way, but now genius has prevailed and we have a potent challenge to conventional spectroscopy. I t should convince the most doubtful that the phenomenological studies are still useful and all progress does not depend upon computers. Once more, it confirms the dictum of the inventor and designer, "Never let well enough alone."

ADVANCES

IN

CHEMISTRY SERIES

62

WERNER CENTENNIAL ADVANCES IN CHEMISTRY SERIES NO. 62 F o r t y - t w o papers survey the w o r k of A l f r e d W e r n e r , founder and systematizer of c o o r d i n a t i o n chemistry, evaluate progress since his time, and report current research in this active

field. •

Personal Werner

recollections

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The W e r n e r - J ^ r g e n s e n versy

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W e r n e r and cobalt complexes

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Nomenclature compounds

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C o o r d i n a t i o n in the second sphere

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Masking of ligand reactivity

of

of

Alfred contro-

coordination

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Linkage isomerism

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Chemistry of cyclobutadiene-iron tricarbonyl and many other topics.

661 pages with index Cloth bound (1967) $15.00 postpaid in U.S. and Canada; plus 20 cents foreign and PUAS. Sel of L. C. cards free with library orders.

Order from: Dept. Β

SPECIAL ISSUES SALES A M E R I C A N CHEMICAL SOCIETY 1155 SIXTEENTH ST., N.W. W A S H I N G T O N , D. C. 20036