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We report the measurement of ultrafast relaxation dynamics of excited states of the carbon dioxide molecule using time-resolved pump-probe photoelectron spectroscopy. Neutral ground-state carbon dioxide is excited to 𝑛⁢𝑑⁢𝜎𝑔 Henning sharp Rydberg states with an attosecond extreme ultraviolet pulse train. A time-delayed near-infrared probe pulse is used to photoionize these states to their corresponding ionization limit 𝐵⁢2⁢Σ𝑢⁢+. We obtain differential kinetic energy spectrograms and angular distributions for photoionization and autoionization channels. We model the competition between predissociation and autoionization in the Rydberg-state dynamics and analyze the differential photoelectron yield as a function of the time delay to extract autoionization and predissociation lifetimes for three Henning sharp states 𝑛=4,5,6. 

The nuclear structure of the⁹⁸Zr nucleus was studied through theβ⁻decay of⁹⁸Y_g.s.at the TRIUMF-ISAC facility. The use of the 8π γ-ray spectrometer with its ancillary detectors SCEPTAR and PACES enabled γ-γ and γ-e⁻coincidence measurements as well as γ-γ angular correlations. The level spin assignments and transition mixing ratios obtained in this study were in good agreement with previous results. Furthermore, 12 previously unknown states in the low-energy region of⁹⁸Zr were identified, including the 0⁺₅and 0⁺₆levels at 2418 and 2749 keV, respectively. The 2⁺and I=1 natures for multiple newly observed and previously known (but not firmly assigned) states have been established. Additionally, the previously assumed pureE2 character of the 2⁺₂→ 2⁺₁367.8-keV transition was confirmed. 

Abstract Metrology of electron wavepackets is often conducted with the technique of photoelectron interferometry. However, the ultrashort light pulses employed in this method place a limit on the energy resolution. Here, weadvance ultrafast photoelectron interferometry access both high temporal and spectral resolution. The key to our approach lies in stimulating Raman interferences with a probe pulse and while monitoring the modification of the autoionizing electron yield in a separate delayed detection step. As a proof of the principle, we demonstrated this technique to obtain the components of an autoionizing nf′ wavepacket between the spin-orbit split ionization thresholds in argon. We extracted the amplitudes and phases from the interferogram and compared the experimental results with second-order perturbation theory calculations. This high resolution probing and metrology of electron dynamics opens the path for study of molecular wavepackets. 

A model that maps the requisite skills, or knowledge components, to the contents of an online course is necessary to implement many adaptive learning technologies. However, developing a skill model and tagging courseware contents with individual skills can be expensive and error prone. We propose a technology to automatically identify latent skills from instructional text on existing online courseware called Smart (Skill Model mining with Automated detection of Resemblance among Texts). Smart is capable of mining, labeling, and mapping skills without using an existing skill model or student learning (aka response) data. The goal of our proposed approach is to mine latent skills from assessment items included in existing courseware, provide discovered skills with human-friendly labels, and map didactic paragraph texts with skills. This way, mapping between assessment items and paragraph texts is formed. In doing so, automated skill models produced by Smart will reduce the workload of courseware developers while enabling adaptive online content at the launch of the course. In our evaluation study, we applied Smart to two existing authentic online courses. We then compared machine-generated skill models and human-crafted skill models in terms of the accuracy of predicting students’ learning. We also evaluated the similarity between machine-generated and human-crafted skill models. The results show that student models based on Smart-generated skill models were equally predictive of students’ learning as those based on human-crafted skill models— as validated on two OLI (Open Learning Initiative) courses. Also, Smart can generate skill models that are highly similar to human-crafted models as evidenced by the normalized mutual information (NMI) values.