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The interplay between electronic and nuclear motions in molecules is a central concept in molecular science. To what extent it influences attosecond photoionization delays is an important, still unresolved question. Here, we apply attosecond electron-ion coincidence spectroscopy and advanced calculations that include both electronic and nuclear motions to study the photoionization dynamics of CH 4 and CD 4 molecules. These molecules are known to feature some of the fastest nuclear dynamics following photoionization. Remarkably, we find no measurable delay between the photoionization of CH 4 and CD 4 , neither experimentally nor theoretically. However, we measure and calculate delays of up to 20 as between the dissociative and non-dissociative photoionization of the highest-occupied molecular orbitals of both molecules. Experiment and theory are in quantitative agreement. These results show that, in the absence of resonances, even the fastest nuclear motion does not substantially influence photoionization delays, but identify a previously unknown signature of nuclear motion in dissociative-ionization channels. These findings have important consequences for the design and interpretation of attosecond chronoscopy in molecules, clusters, and liquids. The role of nuclear motion on photoionization delays is an interesting open question. Here the authors study photoionization delays in dissociative and non-dissociative ionization of a polyatomic molecule and explore the effect of isotopic substitution.

An attosecond molecular interferometer is proposed by using a XUV–XUV pump-probe scheme. The interferograms resulting in the photoelectron distributions enable the full reconstruction of the molecular wave packet associated to excited states using a quantum state holographic approach that, to our knowledge, has only been proposed for simple atomic targets combining attosecond XUV pulses with IR light. In contrast with existing works, we investigate schemes where one- and two-photon absorption paths contribute to ionize the hydrogen molecule and show that it is possible to retrieve the excitation dynamics even when imprinted in a minority channel. Furthermore, we provide a systematic analysis of the time-frequency maps that reveal the distinct, but tightly coupled, motion of electrons and nuclei.

High harmonic light sources make it possible to access attosecond timescales, thus opening up the prospect of manipulating electronic wave packets for steering molecular dynamics. However, two decades after the birth of attosecond physics, the concept of attosecond chemistry has not yet been realized; this is because excitation and manipulation of molecular orbitals requires precisely controlled attosecond waveforms in the deep UV, which have not yet been synthesized. Here, we present a unique approach using attosecond vacuum UV pulse-trains to coherently excite and control the outcome of a simple chemical reaction in a deuterium molecule in a non-Born–Oppenheimer regime. By controlling the interfering pathways of electron wave packets in the excited neutral and singly ionized molecule, we unambiguously show that we can switch the excited electronic state on attosecond timescales, coherently guide the nuclear wave packets to dictate the way a neutral molecule vibrates, and steer and manipulate the ionization and dissociation channels. Furthermore, through advanced theory, we succeed in rigorously modeling multiscale electron and nuclear quantum control in a molecule. The observed richness and complexity of the dynamics, even in this very simplest of molecules, is both remarkable and daunting, and presents intriguing new possibilities for bridging the gap between attosecond physics and attochemistry.

Understanding the coupled electronic and nuclear dynamics in molecules by using pump—probe schemes requires not only the use of short enough laser pulses but also wavelengths and intensities that do not modify the intrinsic behavior of the system. In this respect, extreme UV pulses of few-femtosecond and attosecond durations have been recognized as the ideal tool because their short wavelengths ensure a negligible distortion of the molecular potential. In this work, we propose the use of two twin extreme UV pulses to create a molecular interferometer from direct and sequential two-photon ionization processes that leave the molecule in the same final state. We theoretically demonstrate that such a scheme allows for a complete identification of both electronic and nuclear phases in the wave packet generated by the pump pulse. We also show that although total ionization yields reveal entangled electronic and nuclear dynamics in the bound states, doubly differential yields (differential in both electronic and nuclear energies) exhibit in addition the dynamics of autoionization, i.e., of electron correlation in the ionization continuum. Visualization of such dynamics is possible by varying the time delay between the pump and the probe pulses.

Forest aboveground biomass (AGB) estimation over large extents and high temporal resolution is crucial in managing Mediterranean forest ecosystems, which have been predicted to be very sensitive to climate change effects. Although many modeling procedures have been tested to assess forest AGB, most of them cover small areas and attain high accuracy in evaluations that are difficult to update and extrapolate without large uncertainties. In this study, focusing on the Region of Murcia in Spain (11,313 km2), we integrated forest AGB estimations, obtained from high-precision airborne laser scanning (ALS) data calibrated with plot-level ground-based measures and bio-geophysical spectral variables (eight different indices derived from MODIS computed at different temporal resolutions), as well as topographic factors as predictors. We used a quantile regression forest (QRF) to spatially predict biomass and the associated uncertainty. The fitted model produced a satisfactory performance (R2 0.71 and RMSE 9.99 t·ha−1) with the normalized difference vegetation index (NDVI) as the main vegetation index, in combination with topographic variables as environmental drivers. An independent validation carried out over the final predicted biomass map showed a satisfactory statistically-robust model (R2 0.70 and RMSE 10.25 t·ha−1), confirming its applicability at coarser resolutions.

A single chirped few-femtosecond pulse can be used to control and image coupled electron-nuclear dynamics. Using full ab initio simulations of the simplest molecule, H 2 + , as a prototype target, we show that for intermediate values of the chirp, interference between sequential and direct contributions enables significant control over ionization yields, even when taking into account the effective decoherence introduced by nuclear motion and the presence of an electronic continuum. For larger values of the chirp, the single chirped pulse reproduces a classical pump-probe setup, with the chirp parameter mapping an effective time delay between the pumping and probing frequencies of the pulse. After demonstrating this numerically, we present a full analytical solution for the two-photon ionization amplitudes that provides an intuitive analogy between the molecular dynamics induced by a single chirped pulse and a traditional pump-probe setup.

Effective use of virtual simulations in the science classroom improves comprehension of concepts and models, increases motivation, and promotes acquisition of scientific competences. Despite these benefits, their use in secondary teaching is not widespread. This work analyses the factors that influence use of virtual simulations by science teachers in secondary education. To do this, a mixed study with 609 STEM teachers was performed. The results showed limited use of virtual simulations, significant demand for training in them, and three principal problems that hinder their use: logistics in schools; availability of simulations; and teachers’ time constraints and need for training in how to use them. Accordingly, there is a need to implement educational policies and training programmes that take into account teachers’ problems in searching for simulations and integrating them in the classroom.

Virtual simulations in science classes are not used as often as might be expected if we consider the demonstrated improvement in students’ conceptual learning, the development of their skills, and their acquisition of positive emotions. This makes it necessary to identify teachers’ attitudes and perceptions to the use of these tools. The aim of this work is to construct and validate an instrument for measuring the attitudes of secondary education teachers towards the use of virtual simulations in STEM fields. Based on an in-depth theoretical review, we developed an initial questionnaire that was subjected to a process of expert validation and a pilot study. A questionnaire comprising 27 items was obtained, which was applied to 783 secondary school teachers in Spain. After carrying out confirmatory factor analysis, a scale comprising five factors was obtained. The psychometric analyses displayed satisfactory fit indices that prove the discriminant and convergent validity of the model. The result is a useful instrument for determining the principal factors that discourage teachers from habitually using simulations. This enables the design of training proposals that take teachers’ prior attitudes into account.

The five members of the family of tumor suppressors ING contain a Plant Homeodomain (PHD) that specifically recognizes histone H3 trimethylated at lysine 4 (H3K4me3) with an affinity in the low micromolar range. Here, we use NMR to show that in the presence of 15% Ficoll 70, an inert macromolecular crowding agent, the mode of binding does not change but the affinity increases by one order of magnitude. The affinity increases also for unmethylated histone H3 tail, but the difference with H3K4me3 is larger in the presence of Ficoll. These results indicate that in the cellular milieu, the affinity of the ING proteins for their chromatin target is larger than previously thought.

The aim of this research is to determine the impact of perceived Teachers’ Digital Competence (TDC) on how well math teachers prepare the educational videos needed to put the flipped classroom model into practice. In preparing the videos, the teachers had to select pre-existing audiovisual material and then edit the content to adapt it to the flipped classroom. Described here is a non-experimental study of a sample of 50 teachers pursuing a Master’s degree in Secondary School Math Education in Spain. This is a preliminary univariate descriptive study of the relationship between TDC and the quality of videos prepared. Possible correlations between these two variables and between the characteristics of the sample are also explored. In general, the teachers had an intermediate level of TDC and prepared satisfactory videos. Nevertheless, the videos were deficient in the sections related to their pedagogical and math instructional components. No correlation was observed between TDC and the quality of the videos prepared. These results indicate that the integration of technological, pedagogical, and math instructional components is more important for developing quality instructional videos than the technological component alone. Teacher training should incorporate elements which emphasize the application of technology to the pedagogical process of math instruction.