摘要:

AbstractOne hundred and twenty‐five years ago, on November 11th, 1867, the German Chemical Society of Berlin held its inaugural meeting. The main purpose of the Society was to unite pure and applied chemistry and to foster cooperation between academic research and the chemical industry. And, indeed, it soon became the major forum of German and even European chemistry. Its program clearly bears the hallmark of a single individual: August Wilhelm Hofmann, the Society's first president, who died 100 years ago. For his contemporaries, Hofmann represented a new type of chemistry professor. At no time since have professional chemists felt as abundantly endowed with potential for the future and with public esteem. Hofmann's portrait was monumental even then, and still today it would belong in any gallery devoted to our distinguished forebears.Anniversaries provide an opportunity to direct our attention toward the past—and thus to ourselves as well. We are, after all, heirs to that period from which the modern world derives its profile. Questions from our own time lead us to reacquaint ourselves with one of the founders of modern chemistry, but we may also benefit from a fresh look at an epoch which, beneath the surface of prosperity and progress, was as contradictory as our own, an epoch struggling to understand the role of science in the new industrial

ISSN:0570-0833    

DOI:10.1002/anie.199212653

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIn the GALLium Experiment, GALLEX, low‐energy solar neutrinos produced in the main hydrogen fusion reaction inside the Sun are being counted for the first time in a radiochemical gallium detector. In this way, the theories about stellar structure may be verified and the question of the existence of a neutrino rest mass be brought closer to a solution. The experiment is being carried out with international collaboration at the Gran Sasso underground laboratory (LNGS) in the Abruzzi mountains in Italy. In this paper we survey the planning, construction and initial experimental operation of the gallium detector, paying special attention to the chemical aspects of the experiment. The chemical problem to be solved is the separation of very few71Ge atoms from 100 metric tons of a highly concentrated GaCl3solution acidified with hydrochloric acid. In addition, these Ge atoms must be isolated and converted into germane, GeH4, for low‐level counting of71Ge in a gas proportional counter. After extensive preparatory work to meet the extreme requirements of the experiment, the first results have now become availa

ISSN:0570-0833    

DOI:10.1002/anie.199212831

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractWhen Kekulé awoke from dreams of snakes biting their own tails, he didn't have the benefit of a scanning tunneling microscope (STM) image to confirm that his vision of benzene as a cyclic molecule was accurate. References to STM in the chemical literature increase steadily, although the technique was perhaps oversold in its early days of the 1980s, with such promises as DNA sequencing and tailored bi‐molecular chemical reactions (literally, two molecules). Publications alternate between attempting to explain the process by which images of traditional insulators are obtained and simply presenting the end images themselves as stunning views of atoms and molecules. While imaging mechanisms are still being debated, these instruments' ability to “see” single molecules has been established, albeit at the fringes of our expectations. For example, whereas STM studies at present might not be able to answer the question of why adsorption of CO doubles the density of platinum atoms on the surface of a single crystal of the metal, the images go far in illustrating that thisisa process which platinum undergoes. As with any emerging analytical tool, these scanning, very localized microscopic methods are undergoing the growing pains of irreproducible results and mis‐marketed artifacts. Nonetheless, we assemble here, primarily for the uninitiated, a collection of careful and credible studies to mark the progress of scanning tunneling microscopy and atomic force microscopy into chemistry, and to encourage a healthy blend of idealism and skepticism toward fut

ISSN:0570-0833    

DOI:10.1002/anie.199212981

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213291

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213321

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213351

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213361

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213381

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213391

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY

ISSN:0570-0833    

DOI:10.1002/anie.199213411

出版商:Hüthig&Wepf Verlag    

年代:1992

数据来源: WILEY