Measurement of Time Dependent Product Branching Ratios Indicates Two-State Reactivity in Metal Mediated Chemical Reactions

For several decades, the influence of Two State Reactivity (TSR) has been implicated in a host of reactions, but has lacked a stand-alone, definitive experimental kinetic signature identifying its occurrence....

Molecular synthesis in ices triggered by dissociative electron attachment to carbon monoxide

Chemical reactions in mixed molecular ices as relevant in the context of astrochemistry can be initiated by electron-molecule interactions. Dissociative electron attachment (DEA) as initiating step is identified from the enhancement of product yields upon irradiation at particular electron energies. Herein, we show that DEA to CO leads to the formation of HCN in mixed CO/$$\hbox {NH}_{{3}}$$ NH 3 ice at electron energies around 11 eV and 16 eV. We propose that this reaction proceeds via insertion of the neutral C fragment into a N–H bond. In the case of CO/$$\hbox {H}_{{2}}$$ H 2 O and CO/$$\hbox {CH}_{{3}}$$ CH 3 OH ices, a resonant enhancement of the yields of HCOOH and $$\hbox {CH}_{{3}}$$ CH 3 OCHO, respectively, is observed around 10 eV. In both ices, both molecular constituents exhibit DEA processes in this energy range so that the energy-dependent product yield alone does not uniquely identify the relevant DEA channel. However, we demonstrate by comparing with earlier results on mixed ices where CO is replaced by $$\hbox {C}_{{2}}\hbox {H}_{{4}}$$ C 2 H 4 that DEA to CO is again responsible for the enhanced product formation. In this case, $$\hbox {O}^{\cdot -}$$ O · - activates $$\hbox {H}_{{2}}$$ H 2 O or $$\hbox {CH}_{{3}}$$ CH 3 OH which leads to the formation of larger products. We thus show that DEA to CO plays an important role in electron-induced syntheses in molecular ices. Graphical abstract

Killing Ambition

This chapter seeks to account for the nearly complete absence of warfare from medieval Iceland and its sagas. It argues that a single logic dictated both the embrace of feud as a socially constructive idea and the rejection of war as an abomination. Drawing on anthropological examples and analyses, war is defined by contrasting it with feud; the bond between war and state-formation is emphasized. War presupposes political centralization and differentiation, which Icelanders, committed to the reciprocal logic of feuding, resisted. According to the sagas, ideological opposition to war manifested itself in abortive attempts at political consolidation within Iceland, in confusion and substitution in the face of war elsewhere (in Norway, England, and North America), and in failure to contend with burgeoning warlike activity in thirteenth-century Iceland. Tensions between state-centric warfare and state-resistant feuding existed in historical reality, however, not only in saga accounts of this history; and in reality, tensions could not always be resolved. Uchronia provided a tool for creative, retrospective textual resolution of problems that could not be overcome in practice. As demonstrated by the Icelandic law code, Grágás, the past thus became the path-dependent product of the future. Uchronic ideology worked to emend any perceived historical ‘errors’: any symptoms of war that could not be suppressed in reality were, instead, overwritten and repressed in text

Evaluation of the Pr + O → PrO+ + e− chemi-ionization reaction enthalpy and praseodymium oxide, carbide, dioxide, and carbonyl cation bond energies

Guided ion beam tandem mass spectrometry was used to measure the kinetic energy dependent product ion cross sections for reactions of the lanthanide metal praseodymium cation (Pr+) with O2, CO2, and CO and reactions of PrO+ with CO, O2, and Xe.