31 research outputs found
Molecular movie of ultrafast coherent rotational dynamics of OCS
Recording molecular movies on ultrafast timescales has been a longstanding goal for unravelling detailed information about molecular dynamics. Here we present the direct experimental recording of very-high-resolution and -fidelity molecular movies over more than one-and-a-half periods of the laser-induced rotational dynamics of carbonylsulfide (OCS) molecules. Utilising the combination of single quantum-state selection and an optimised two-pulse sequence to create a tailored rotational wavepacket, an unprecedented degree of field-free alignment, 〈cos2θ2D〉 = 0.96 (〈cos2θ〉 = 0.94) is achieved, exceeding the theoretical limit for single-pulse alignment. The very rich experimentally observed quantum dynamics is fully recovered by the angular probability distribution obtained from solutions of the time-dependent Schrödinger equation with parameters refined against the experiment. The populations and phases of rotational states in the retrieved time-dependent three-dimensional wavepacket rationalises the observed very high degree of alignment
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Molecular movie of ultrafast coherent rotational dynamics of OCS
Recording molecular movies on ultrafast timescales has been a longstanding goal for unravelling detailed information about molecular dynamics. Here we present the direct experimental recording of very-high-resolution and -fidelity molecular movies over more than one-and-a-half periods of the laser-induced rotational dynamics of carbonylsulfide (OCS) molecules. Utilising the combination of single quantum-state selection and an optimised two-pulse sequence to create a tailored rotational wavepacket, an unprecedented degree of field-free alignment, 〈cos2θ2D〉 = 0.96 (〈cos2θ〉 = 0.94) is achieved, exceeding the theoretical limit for single-pulse alignment. The very rich experimentally observed quantum dynamics is fully recovered by the angular probability distribution obtained from solutions of the time-dependent Schrödinger equation with parameters refined against the experiment. The populations and phases of rotational states in the retrieved time-dependent three-dimensional wavepacket rationalises the observed very high degree of alignment
Atomic-resolution imaging of carbonyl sulfide by laser-induced electron diffraction
Measurements on the strong-field ionization of carbonyl sulfide molecules by short, intense, 2 µm wavelength laser pulses are presented from experiments where angle-resolved photoelectron distributions were recorded with a high-energy velocity map imaging spectrometer, designed to reach a maximum kinetic energy of 500 eV. The laser-field-free elastic-scattering cross section of carbonyl sulfide was extracted from the measurements and is found in good agreement with previous experiments, performed using conventional electron diffraction. By comparing our measurements to the results of calculations, based on the quantitative rescattering theory, the bond lengths and molecular geometry were extracted from the experimental differential cross sections to a precision better than ±5 pm and in agreement with the known values
Future response of global coastal wetlands to sea-level rise.
The response of coastal wetlands to sea-level rise during the twenty-first century remains uncertain. Global-scale projections suggest that between 20 and 90 per cent (for low and high sea-level rise scenarios, respectively) of the present-day coastal wetland area will be lost, which will in turn result in the loss of biodiversity and highly valued ecosystem services1-3. These projections do not necessarily take into account all essential geomorphological4-7 and socio-economic system feedbacks8. Here we present an integrated global modelling approach that considers both the ability of coastal wetlands to build up vertically by sediment accretion, and the accommodation space, namely, the vertical and lateral space available for fine sediments to accumulate and be colonized by wetland vegetation. We use this approach to assess global-scale changes in coastal wetland area in response to global sea-level rise and anthropogenic coastal occupation during the twenty-first century. On the basis of our simulations, we find that, globally, rather than losses, wetland gains of up to 60 per cent of the current area are possible, if more than 37 per cent (our upper estimate for current accommodation space) of coastal wetlands have sufficient accommodation space, and sediment supply remains at present levels. In contrast to previous studies1-3, we project that until 2100, the loss of global coastal wetland area will range between 0 and 30 per cent, assuming no further accommodation space in addition to current levels. Our simulations suggest that the resilience of global wetlands is primarily driven by the availability of accommodation space, which is strongly influenced by the building of anthropogenic infrastructure in the coastal zone and such infrastructure is expected to change over the twenty-first century. Rather than being an inevitable consequence of global sea-level rise, our findings indicate that large-scale loss of coastal wetlands might be avoidable, if sufficient additional accommodation space can be created through careful nature-based adaptation solutions to coastal management.Personal research fellowship of Mark Schuerch (Project Number 272052902) and by the Cambridge Coastal Research Unit (Visiting Scholar Programme). Furthermore, this work has partly been supported by the EU research project RISES-AM- (FP7-ENV-693396)
Asymmetric nucleophilic acylation with metalated aminonitriles : diastereo- and enantioselective synthesis of 2-substituted 3-aroyl-cyclohexanones via tandem Michael addition / -alkylation
CYCLOADDITIONS .31. CHIRAL DIENOPHILES DERIVED FROM MALIC-ACID - SYNTHESIS OF (Z)-(2S)-(TERT-BUTYL)-5-(ETHOXYCARBONYLMETHYLENE)-1,3-DIOXOLAN-4-ONE AND ITS DIELS-ALDER REACTION WITH CYCLOPENTADIENE
KNEER G, Mattay J, RAABE G, KRUGER C, LAUTERWEIN J. CYCLOADDITIONS .31. CHIRAL DIENOPHILES DERIVED FROM MALIC-ACID - SYNTHESIS OF (Z)-(2S)-(TERT-BUTYL)-5-(ETHOXYCARBONYLMETHYLENE)-1,3-DIOXOLAN-4-ONE AND ITS DIELS-ALDER REACTION WITH CYCLOPENTADIENE. Synthesis. 1990;(7):599-603
Conception of a modular load carrier for the transportation of Euro containers for the aircraft production
Euronormbehälter haben sich in vielen Industriezweigen als Standard für den Transport und die Lagerung von Kleinteilen jeglicher Art durchgesetzt. Ein vollständig automatisierter Transport zwischen Lagerplatz und Bauplatz ist in der Regel jedoch nicht möglich und wird zumindest teilweise manuell über Rollcontainer o.ä. umgesetzt. Bisherige Ladungsträgerkonzepte für Euronormbehälter sind allerdings nicht skalierbar und bedingen ein häufiges Umpacken und Verdichten der Euronormbehälter. Dieser Beitrag stellt ein Konzept eines modularen Ladungsträgers für Euronormbehälter vor, welches sich durch koppelbare Ladungsträgermodule, die sich zu größeren Verbunden kombinieren lassen, auszeichnet. Hierdurch werden der Volumennut-zungsgrad und die Flexibilität verbessert und schlankere Logistikprozesse erreicht.Euro containers are established in almost every industry for the transport and storage of small-parts. However, a fully automated transport between storage location and point-of-use is not always possible and instead realized by manual transport with rollable load carriers. State of the art load carrier concepts for con-tainers are not scalable and need to be repacked and densified very often. In order to encounter this problem, this article deals with connectable load carrier modules which can be combined to individual load carrier units. This improves the volume efficiency and flexibility and enables leaner logistics processes