Quantum-Chemical Approach to Nuclear Magnetic Resonance of Paramagnetic Systems

Nuclear magnetic resonance (NMR) is a central method for investigating the microscopic structure and dynamics of molecules and materials, with numerous applications in science, technology, and medicine. Computational modelling is indispensable in NMR research due to the indirect nature of NMR information and the rich physical phenomenology behind its observables. While NMR is conventionally used to study diamagnetic systems, paramagnetic NMR (pNMR) of electronically open-shell systems is rapidly gaining importance. This inaugural article concerns the methodology and application of computational molecular science to the observables pNMR, including current challenges and outlook for the future.Nuclear magnetic resonance (NMR) is a central method for investigating the microscopic structure and dynamics of molecules and materials, with numerous applications in science, technology, and medicine. Computational modelling is indispensable in NMR research due to the indirect nature of NMR information and the rich physical phenomenology behind its observables. While NMR is conventionally used to study diamagnetic systems, paramagnetic NMR (pNMR) of electronically open-shell systems is rapidly gaining importance. This inaugural article concerns the methodology and application of computational molecular science to the observables pNMR, including current challenges and outlook for the future

Observation of optical chemical shift by precision nuclear spin optical rotation measurements and calculations

Nuclear spin optical rotation (NSOR) is a recently developed technique for detection of nuclear magnetic resonance via rotation of light polarization, instead of the usual long-range magnetic fields. NSOR signals depend on hyperfine interactions with virtual optical excitations, giving new information about the nuclear chemical environment. We use a multi-pass optical cell to perform first precision measurements of NSOR signals for a range of organic liquids and find clear distinction between proton signals for different compounds, in agreement with our earlier predictions. Detailed first principles quantum-mechanical NSOR calculations are found to be in good agreement with the measurements.Comment: 4 page

Taking historical embeddedness seriously : Three historical approaches to advance strategy process and practice research

International audienceDespite the proliferation of strategy process and practice research, we lack understanding of the historical embeddedness of strategic processes and practices. In this paper, we present three historical approaches with the potential to remedy this deficiency. First, realist history can contribute to a better understanding of the historical embeddedness of strategic processes; in particular, comparative historical analysis can explicate the historical conditions, mechanisms, and causality in strategic processes. Second, interpretative history can add to our knowledge of the historical embeddedness of strategic practices, and microhistory can specifically help to understand the construction and enactment of these practices in historical contexts. Third, poststructuralist history can elucidate the historical embeddedness of strategic discourses, and genealogy can in particular increase our understanding of the evolution and transformation of strategic discourses and their power effects. Thus, this paper demonstrates how in their specific ways historical approaches and methods can add to our understanding of different forms and variations of strategic processes and practices, the historical construction of organizational strategies, and historically constituted strategic agency.<br/

NMR tensors in planar hydrocarbons of increasing size

Peer reviewe

nuclear spin circular dichroism in fullerenes a computational study

Chemically different carbons in C70 give distinct signals in nuclear spin circular dichroism spectroscopy, a novel candidate for high-resolution identification of chemical compounds

Taking historical embeddedness seriously:three approaches to advance strategy process and practice research

Despite the proliferation of strategy process and practice research, we lack understanding of the historical embeddedness of strategic processes and practices. In this paper, we present three historical approaches with the potential to remedy this deficiency. First, realist history can contribute to a better understanding of the historical embeddedness of strategic processes; in particular, comparative historical analysis can explicate the historical conditions, mechanisms, and causality in strategic processes. Second, interpretative history can add to our knowledge of the historical embeddedness of strategic practices, and microhistory can specifically help to understand the construction and enactment of these practices in historical contexts. Third, poststructuralist history can elucidate the historical embeddedness of strategic discourses, and genealogy can in particular increase our understanding of the evolution and transformation of strategic discourses and their power effects. Thus, this paper demonstrates how in their specific ways historical approaches and methods can add to our understanding of different forms and variations of strategic processes and practices, the historical construction of organizational strategies, and historically constituted strategic agency

Relation between molecular electronic structure and nuclear spin-induced circular dichroism

The recently theoretically described nuclear spin-induced circular dichroism (NSCD) is a promising method for the optical detection of nuclear magnetization. NSCD involves both optical excitations of the molecule and hyperfine interactions and, thus, it offers a means to realize a spectroscopy with spatially localized, high-resolution information. To survey the factors relating the molecular and electronic structure to the NSCD signal, we theoretically investigate NSCD of twenty structures of the four most common nucleic acid bases (adenine, guanine, thymine, cytosine). The NSCD signal correlates with the spatial distribution of the excited states and couplings between them, reflecting changes in molecular structure and conformation. This constitutes a marked difference to the nuclear magnetic resonance (NMR) chemical shift, which only reflects the local molecular structure in the ground electronic state. The calculated NSCD spectra are rationalized by means of changes in the electronic density and by a sum-over-states approach, which allows to identify the contributions of the individual excited states. Two separate contributions to NSCD are identified and their physical origins and relative magnitudes are discussed. The results underline NSCD spectroscopy as a plausible tool with a power for the identification of not only different molecules, but their specific structures as well.Peer reviewe

Laser-induced splittings in the nuclear magnetic resonance spectra of the rare gases

Circularly polarized laser field causes a shift in the nuclear magnetic resonance (NMR) spectra of all substances. The shift is proportional to the intensity of the laser beam and yields oppositely signed values for left- and right-circularly polarized light, CPL -/+, respectively. Rapid switching -- in the NMR time scale -- between CPL+ and CPL- gives rise to a splitting of the NMR resonance lines. We present uncorrelated and correlated quadratic response calculations of the splitting per unit of beam intensity in the NMR spectra of $^{21}$Ne, $^{83}$Kr, and $^{129}$Xe. We study both the regions far away from and near to optical resonance and predict off-resonance shifts of the order 0.01, 0.1, and $1\times 10^{-6}$ Hz for $^{21}$Ne, $^{83}$Kr, and $^{129}$Xe, respectively, for a beam intensity of 10 W/cm$^2$. Enhancement by several orders of magnitude is predicted as the beam frequency approaches resonance. Only then can the effect on guest $^{129}$Xe atoms be potentially useful as a probe of the properties of the host material.Comment: 5 pages, 1 figur

Magneettikuvauksen ABC: T1, T2, fat sat, DWI ynnä muut : radiologin salakieli auki kirjoitettuna

Vertaisarvioitu. Näin tutkin.Magneettikuvien tulkinta edellyttää magneettifysiikan perusteiden ymmärtämistä. Magneettikuvaussekvenssejä voidaan painottaa eri tavoin, jolloin kudokset erottuvat erilaisina. Kuvauksissa erilaiset sekvenssit täydentävät toisiaan ja tuovat kukin lisää informaatiota, jolloin syntyy kokonaiskäsitys kuvatusta kohteesta. Käytettävät sekvenssit ovat eri kysymyksenasettelujen yhteydessä erilaisia, ja paikalliset käytännöt voivat vaihdella. Kaikki potilaat eivät kaikissa tilanteissa sovellu magneettikuvaukseen, johon voi liittyä myös turvallisuusriskejä esimerkiksi kehonsisäisten vierasesineiden vuoksi. Radiologin lausunto sisältää kliinikkoa varten tehdyn tulkinnan lisäksi radiologiset perustelut siitä, miten tulkintaan on päädytty. Radiologiset termit helpottavat radiologien keskinäistä kommunikaatiota seurantakuvauksissa, mutta saattavat hämmentää kliinikkoa. Kokoustoiminta tukee perehtymistä oman alan kuvantamiseen sekä edistää kliinikoiden ja radiologien välistä yhteistyötä