Neuere Ergebnisse der Elektronenbeugung

Early Days of Gas Electron Diffraction Studies in Japan

“…Internal rotation in 1,2-dichloroethane was one of the many key subjects of structural chemistry [8] that had already been taken up in the first GED paper by Mark and Wierl [9]. There they remarked: "Es scheinen zwei Gleichgewichtslagen vorzuliegen, die einer cis-und translage entsprechen."…”

“…Kohlrausch assigned his Raman spectrum of dichloroethane to a mixture of trans and cis forms [13], probably influenced by Wierl's preceding papers of GED [9][10][11].…”

Looking Back and Ahead: Gas-Phase Electron Diffraction at 75

“…The first paper describing gas-phase electron diffraction appeared in 1930; its authors were Herman F. Mark and Raimund Wierl [1]. Mark was a chemist who later became famous for his pioneering polymer studies and Wierl was a physicist, who died young.…”

“…Then Louis de Broglie concluded the wave-particle duality of fast-moving particles, and the experimental verification on solids was given by Davisson and Germer for slow electrons [3] and by Thomson for fast electrons [4]. The very first gas-phase electron diffraction experiment [1] was carried out on carbon tetrachloride vapor; it used 45-kV electrons and an exposure time of a tenth of a second! In a straightforward way, Mark and Wierl determined the C Cl interatomic distance from the electron diffraction pattern, which was orders of magnitude quicker to produce, and it was less diffuse and of higher contrast than the X-ray diffraction patterns [5].…”

“…Numerous references to electron diffraction structure information can be found in Linus Pauling's classic, The Nature of the Chemical Bond indicating the fundamental importance of this information in the development of chemical concepts. Accounts of history can be found, among others, in Mark's Introduction [1] and Jerome Karle's Foreword [6] to a 1988 monograph on gas-phase electron diffraction, in Lawrence Bartell's paper in this issue of Structural Chemistry, [7] and elsewhere.…”