Strong-field control of the dissociative ionization of N2O with near-single-cycle pulses

The dissociative ionization of N2O by near-single-cycle laser pulses is studied using phase-tagged ion-ion coincidence momentum imaging. Carrier-envelope phase (CEP) dependences are observed in the absolute ion yields and the emission direction of nearly all ionization and dissociation pathways of the triatomic molecule. We find that laser-field-driven electron recollision has a significant impact on the dissociative ionization dynamics and results in pronounced CEP modulations in the dication yields, which are observed in the product ion yields after dissociation. The results indicate that the directional emission of coincident N+ and NO+ ions in the denitrogenation of the dication can be explained by selective ionization of oriented molecules. The deoxygenation of the dication with the formation of coincident N-2(+) + O+ ions exhibits an additional shift in its CEP dependence, suggesting that this channel is further influenced by laser interaction with the dissociating dication. The experimental results demonstrate how few-femtosecond dynamics can drive and steer molecular reactions taking place on (much) longer time scales

Topological Order in the Projected Entangled-Pair States Formalism: Transfer Operator and Boundary Hamiltonians

We study the structure of topological phases and their boundaries in the projected entangled-pair states (PEPS) formalism. We show how topological order in a system can be identified from the structure of the PEPS transfer operator and subsequently use these findings to analyze the structure of the boundary Hamiltonian, acting on the bond variables, which reflects the entanglement properties of the system. We find that in a topological phase, the boundary Hamiltonian consists of two parts: A universal nonlocal part which encodes the nature of the topological phase and a nonuniversal part which is local and inherits the symmetries of the topological model, which helps to infer the structure of the boundary Hamiltonian and thus possibly of the physical edge modes

Tabletop nonlinear optics in the 100-eV spectral region

Nonlinear light-matter interactions in the extreme ultraviolet (XUV) are a prerequisite to perform XUV-pump/XUV-probe spectroscopy of core electrons. Such interactions are now routinely investigated at free-electron laser (FEL) facilities. Yet, electron dynamics are often too fast to be captured with the femtosecond resolution of state-of-the-art FELs. Attosecond pulses from laser-driven XUV-sources offer the necessary temporal resolution. However, intense attosecond pulses supporting nonlinear processes have only been available for photon energy below 50 eV, precluding XUV-pump/XUV-probe investigation of typical inner-shell processes. Here, we surpass this limitation by demonstrating two-photon absorption from inner electronic shells of xenon at photon energies around 93 eV and 115 eV. This advance opens the door for attosecond real-time observation of nonlinear electron dynamics deep inside atoms

Adaptive strong-field control of chemical dynamics guided by three-dimensional momentum imaging.

Shaping ultrafast laser pulses using adaptive feedback can manipulate dynamics in molecular systems, but extracting information from the optimized pulse remains difficult. Experimental time constraints often limit feedback to a single observable, complicating efforts to decipher the underlying mechanisms and parameterize the search process. Here we show, using two strong-field examples, that by rapidly inverting velocity map images of ions to recover the three-dimensional photofragment momentum distribution and incorporating that feedback into the control loop, the specificity of the control objective is markedly increased. First, the complex angular distribution of fragment ions from the nω+C2D4→C2D3++D interaction is manipulated. Second, isomerization of acetylene (nω+C2H2→C2H22+→CH2++C+) is controlled via a barrier-suppression mechanism, a result that is validated by model calculations. Collectively, these experiments comprise a significant advance towards the fundamental goal of actively guiding population to a specified quantum state of a molecule

Subfemtosecond steering of hydrocarbon deprotonation through superposition of vibrational modes

Subfemtosecond control of the breaking and making of chemical bonds in polyatomic molecules is poised to open new pathways for the laser-driven synthesis of chemical products. The break-up of the C-H bond in hydrocarbons is an ubiquitous process during laser-induced dissociation. While the yield of the deprotonation of hydrocarbons has been successfully manipulated in recent studies, full control of the reaction would also require a directional control (that is, which C-H bond is broken). Here, we demonstrate steering of deprotonation from symmetric acetylene molecules on subfemtosecond timescales before the break-up of the molecular dication. On the basis of quantum mechanical calculations, the experimental results are interpreted in terms of a novel subfemtosecond control mechanism involving non-resonant excitation and superposition of vibrational degrees of freedom. This mechanism permits control over the directionality of chemical reactions via vibrational excitation on timescales defined by the subcycle evolution of the laser waveform

PROK1, biomarqueur de l’implantation embryonnaire ?

International audienceIn spite of improvements in assisted reproductive technology (ART) during the last 30 years, the rate of pregnancy remains constrained, as only about 25 % of embryo transfer lead to successful pregnancies, even with an average of two embryos replaced. Embryo selection is currently based on the establishment of morphokinetic scores, a method that obviously exhibits limitations. Therefore, the assessment of embryo development potency by criteria of higher predictive value is mandatory in order to increase the rates of pregnancy. Nowadays, there is increasing evidence that angiogenic factors might contribute to the success of the implantation and to the pregnancy outcome. Among these factors, prokineticin 1 (PROK1) and its receptors (PROKRs) constitute new targets that showed over the last ten years strong biological features directly linked to ovarian physiology, endometrial receptivity, embryo implantation and thus successful pregnancies. In ART, the rates of circulating PROK1 were reported in 2012 as significantly linked to the quality of embryonic cohort, as well as to the rates of pregnancy. Our preliminary data suggest a high potential of this cytokine in the success of implantation and pregnancy, and strongly overtones the emergency to investigate the value of its measurement in conditioned media of oocytes and embryo cultures in ART

PROK1, biomarqueur de l’implantation embryonnaire ?

International audienceIn spite of improvements in assisted reproductive technology (ART) during the last 30 years, the rate of pregnancy remains constrained, as only about 25 % of embryo transfer lead to successful pregnancies, even with an average of two embryos replaced. Embryo selection is currently based on the establishment of morphokinetic scores, a method that obviously exhibits limitations. Therefore, the assessment of embryo development potency by criteria of higher predictive value is mandatory in order to increase the rates of pregnancy. Nowadays, there is increasing evidence that angiogenic factors might contribute to the success of the implantation and to the pregnancy outcome. Among these factors, prokineticin 1 (PROK1) and its receptors (PROKRs) constitute new targets that showed over the last ten years strong biological features directly linked to ovarian physiology, endometrial receptivity, embryo implantation and thus successful pregnancies. In ART, the rates of circulating PROK1 were reported in 2012 as significantly linked to the quality of embryonic cohort, as well as to the rates of pregnancy. Our preliminary data suggest a high potential of this cytokine in the success of implantation and pregnancy, and strongly overtones the emergency to investigate the value of its measurement in conditioned media of oocytes and embryo cultures in ART