arXiv subjects

Sean Jackson

Publications and source records attributed to Sean Jackson.

3 recordsLinked to original sources

arXiv2026

Rotational spectra and de-perturbation analysis for ground state ytterbium oxide, YbO

A combination difference analysis of Fourier transform microwave spectroscopy (FTMW) measurements of $^{174}$YbO combined with earlier near-infrared chemiluminescence data have resulted in much improved YbO rotational and centrifugal distortion constants. These have been confirmed in a multi-isotopologue analysis of further FTMW measurements of $^{172}$YbO and $^{176}$YbO and an analysis of nuclear-size-dependent Born-Oppenheimer breakdown effects in the molecule. Multiple excited electronic states overlap with low-lying excited vibrational levels of the electronic ground state leading to irregularities in its vibrational spacings and other previously observed electronic manifolds. This has been modeled with a matrix of the vibrational levels of the ground and multiple interacting states assuming Morse potentials and including electronic Hamiltonian matrix elements mixing the states. Vibrational level overlaps were calculated numerically assuming Morse vibrational wavefunctions. The resulting de-perturbed potentials for the states inform continuing experimental and theoretical work on this and other ytterbium-containing molecules.

physics.chem-ph↗

arXiv2026

Sticky Help, Bounded Effects: Session-by-Session Analytics of Teacher Interventions in K-12 Classrooms

Teachers' in-the-moment support is a limited resource in technology-supported classrooms, and teachers must decide whom to help and when during ongoing student work. However, less is known about how students' prior help history (whether they were helped earlier) and their engagement states (e.g., idle, struggle) shape teachers' decisions, and whether observed learning benefits associated with teacher help extend beyond the current class session. To address these questions, we first conducted interviews with nine K-12 mathematics teachers to identify candidate decision factors for teacher help. We then analyzed 1.4 million student-system interactions from 339 students across 14 classes in the MATHia intelligent tutoring system by linking teacher-logged help events with fine-grained engagement states. Mixed-effects models show that students who received help earlier were more likely to receive additional help later, even after accounting for current engagement state. Cross-lagged panel analyses further show that teacher help recurred across sessions, whereas idle behavior did not receive sustained attention over time. Finally, help coincided with immediate learning within sessions, but did not predict skill acquisition in later sessions, as estimated by additive factor modeling. These findings suggest that teacher help is "sticky" in that it recurs for previously supported students, while its measurable learning benefits in our data are largely session-bound. We discuss implications for designing real-time analytics that track attention coverage and highlight under-visited students to support a more equitable and effective allocation of teacher attention.

cs.CY↗

arXiv2024

Rotational and Near-IR Spectra of PbF: Characterization of the Coupled $X_1\,^2\Pi_{1/2}$ and $X_2\,^2\Pi_{3/2}$ States

Observations of the rotational spectrum of lead monofluoride, PbF, have been extended up to transitions in the \textit{v} = 7 level for $^{208}$PbF in the lowest $X_1\,^2\Pi_{1/2}$ state of the radical and \textit{v} = 5 for the $^{207}$Pb and $^{206}$Pb isotopologues. The data also include a few measurements for $^{204}$PbF in \textit{v} = 0. These new measurements have been combined with existing near-IR measurements of the $X_2 - X_1$ fine-structure transition and a simultaneous multi-isotope fit of the data to an effective isotope-independent ro-vibronic Hamiltonian has been carried out. The resulting parameters fully characterize the vibrational, rotational and hyperfine structure of the combined $X_1 \, / \, X_2$ state of the radical. A pair of opposite parity levels with total angular momentum quantum number, $F=1/2$, in the lowest rotational level, $J=1/2$ of \PbF \,are close in energy and their spacing decreases with vibrational excitation. The experimental results show the spacing decreases to less than 20 MHz at $v=7$ and 8. The experimental work is complemented by new \textit{ab initio} calculations which support the results and allow predictions outside the experimental data range. The calculated radiative lifetimes of the relevant vibrationally excited states are of the order of 50 ms. This work was motivated by interest in using \PbF\, as a vehicle for future probes of the standard model of physics such as placing limits on the electron's electric dipole moment (\eEDM), molecular charge-parity non-conservation and Born-Oppenheimer breakdown effects for example.

physics.chem-ph↗