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The National Institute of Standards and Technology (NIST, formerly the National Bureau of Standards or NBS) has produced numerous Standard Reference Materials (SRM) for use in biological and environmental analytical chemistry. The value listed on the “NIST Certificate of Analysis” is the present best estimate of the “true” concentration of that element and is not expected to deviate from that concentration by more than the stated uncertainty. However, NIST does not certify the elemental concentration of every constituent and the number of elements reported in the NIST programs tends to be limited. Numerous analysts have published concentration data on these reference materials. Major journals in analytical chemistry, books, proceedings and “technical reports” have been surveyed to collect these available literature values. A standard statistical approach has been employed to evaluate the compiled data. Our methodology has been developed in a series of previous papers. Some subjective criteria are first used to reject aberrant data. Following these eliminations, an initial arithmetic mean and standard deviation (S.D.) are computed from remaining data for each element. All data now outside two S.D. from the initial mean are dropped and a second mean and S.D. recalculated. These final means and associated S.D. are reported as “consensus values” in our tables. Received: 25 April 1997 / Revised: 24 July 1977 / Accepted: 25 July 1997  相似文献   
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Self-consistent field calculations including the complete overlap matrix have been made to predict the electronic spectra of benzene, napthalene, anthracene and phenanthrene. The results are remarkably similar to those obtained with the neglect of differential overlap.
Zusammenfassung SCF-Rechnungen unter Einschluß der vollständigen Überlappungsmatrix sind zur Bestimmung der Elektronenspektren von Benzol, Naphthalin, Anthracen und Phenanthren unternommen worden. Die Ergebnisse sind den unter Vernachlässigung der differentiellen Überlappung erhaltenen bemerkenswert ähnlich.

Résumé On a fait des calculs SCF avec la matrice complète des recouvrements afin de prédire les spectres électroniques du benzène, du naphtalène, de l'anthracène et du phénanthrène. Les résultats ressemblent remarquablement à ceux obtenus en négligeant le recouvrement différentiel.


Support of the Petroleum Research Fund of the American Chemical Society is gatefully acknowledged. The author has enjoyed the computational assistance of Bell Telephone Laboratories, Murray Hill, N. J.

Porter Ogden Jacokbus Fellow, Princeton University, 1962–63  相似文献   
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