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We present a new mechanism contributing to the detection of photoassociated long-range Rydberg molecules via pulsed-field ionization: ionic products, created by the decay of a long-range Rydberg molecule, modify the excitation spectrum of surrounding ground-state atoms and facilitate the excitation of further atoms into Rydberg states by the photoassociation light. Such an ion-mediated excitation mechanism has been previously called "Coulomb anti-blockade". Pulsed-field ionisation typically doesn't discriminate between the ionization of a long-range Rydberg molecule and an isolated Rydberg atom, and thus the number of atomic ions detected by this mechanism is not proportional to the number of long-range Rydberg molecules present in the probe volume. By combining high-resolution UV and RF spectroscopy of a dense, ultracold gas of cesium atoms, theoretical modeling of the molecular level structures of long-range Rydberg molecules bound below nP_3/2 Rydberg states of cesium, and a rate model of the photoassociation and decay processes, we unambiguously identify the signatures of this detection mechanism in the photoassociation of long-range Rydberg molecules bound below atomic asymptotes with negative Stark shifts., Comment: 8 pages, 7 figures

The mean free paths of low-energy electrons in liquid water are of fundamental importance for modelling radiation damage and many related physico-chemical processes. Neither theoretical predictions nor experimental estimations have so far converged to yield reliable values for these parameters. We therefore introduce a new approach to determine the elastic and inelastic mean free paths (EMFP, IMFP) based on experimental data. We report extensive ab-initio calculations of electron quantum scattering with water clusters, which are brought to convergence with respect to the cluster size. This provides a first-principles approach to condensed-phase scattering that includes both multiple-scattering and condensation effects. The obtained differential cross sections are used in a detailed Monte-Carlo simulation to extract EMFP and IMFP from two recent liquid-microjet experiments that determined the effective attenuation length (EAL) and the photoelectron angular distribution (PAD) following oxygen 1s-ionization of liquid water. For electron kinetic energies from 10 eV to 300 eV, we find that the IMFP is noticeably larger than the EAL. The EMFP is longer than that of gas-phase water and the IMFP is longer compared to the latest theoretical estimations, but both the EMFP and IMFP are much shorter than suggested by experimental results for amorphous ice. The Python module developed for the analysis is available at https://gitlab.com/axelschild/CLstunfti and can be used to further refine our results when new experimental data become available.

We present photodissociation of ultracold long-range Rydberg molecules as a tool to characterize their electronic properties. We photoassociate K2 37P molecules with highly entangled electronic and nuclear spins of the two bound atoms and quantify the entanglement by projection of the molecular state onto non-interacting atoms using radiofrequency photodissociation. By comparison of experimental photodissociation rates with theoretical predictions we further characterize the electronic and nuclear wavefunction of the photoassociated molecules. Based on the complete characterization of the formed long-range Rydberg molecules, we demonstrate a full hyperfine-spin flip of a free ground-state atom through the interaction with a Rydberg atom., 8 pages, 6 figures

Electronic dynamics in liquids are of fundamental importance, but time-resolved experiments have so far remained limited to the femtosecond time scale. We report the extension of attosecond spectroscopy to the liquid phase. We measured time delays of 50 to 70 attoseconds between the photoemission from liquid water and that from gaseous water at photon energies of 21.7 to 31.0 electron volts. These photoemission delays can be decomposed into a photoionization delay sensitive to the local environment and a delay originating from electron transport. In our experiments, the latter contribution is shown to be negligible. By referencing liquid water to gaseous water, we isolated the effect of solvation on the attosecond photoionization dynamics of water molecules. Our methods define an approach to separating bound and unbound electron dynamics from the structural response of the solvent., Science, 369 (6506), ISSN:0036-8075, ISSN:1095-9203

We present the formation of homonuclear Cs2, K2, and heteronuclear CsK long-range Rydberg molecules in a dual-species magneto-optical trap for 39K and 133Cs by one-photon UV photoassociation. The different ground-state-density dependence of homo- and heteronuclear photoassociation rates and the detection of stable molecular ions resulting from auto-ionization provide an unambiguous assignment. We perform bound-bound millimeter-wave spectroscopy of long-range Rydberg molecules to access molecular states not accessible by one-photon photoassociation. Calculations based on the most recent theoretical model and atomic parameters do not reproduce the full set of data from homo- and heteronuclear long-range Rydberg molecules consistently. This shows that photoassociation and millimeter-wave spectroscopy of heteronuclear long-range Rydberg molecules provide a benchmark for the development of theoretical models., (5 pages article + 10 pages appendices, 16 figures)

We propose a new approach to excite ion-pair states of ultracold dimers. The central idea is a two-step process where first long-range Rydberg molecules are formed by photoassociation, which are then driven by stimulated emission towards the ion-pair state, a process bearing features of a photo-induced harpooning reaction. We assess the feasibility of this approach through a detailed experimental and theoretical study on a specific system, p-wave-scattering dominated long-range Rydberg molecules in caesium, and discuss potential applications for the study of strongly correlated plasmas consisting of oppositely charged particles of equal or similar mass., Journal of Physics B: Atomic, Molecular and Optical Physics, 53 (6), ISSN:1361-6455, ISSN:0368-3508, ISSN:0953-4075, ISSN:0022-3700

Physical Review A, 100 (3), ISSN:1094-1622, ISSN:0556-2791, ISSN:1050-2947

We present absolute-frequency measurements in ultracold $^{39}\mathrm{K}$ samples of the transitions from the $4{s}_{1/2}$ ground state to $n{p}_{1/2}$ and $n{p}_{3/2}$ Rydberg states. A global nonlinear regression of the $n{p}_{1/2}$ and $n{p}_{3/2}$ term values yields an improved wave number of 35009.8139710(22)${}_{\mathrm{sys}}{(3)}_{\mathrm{stat}}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ for the first ionization threshold of $^{39}\mathrm{K}$ and the quantum defects of the $n{p}_{1/2}$ and $n{p}_{3/2}$ series. In addition, we report the frequencies of selected one-photon transitions ${n}^{\ensuremath{'}}{s}_{1/2}\ensuremath{\leftarrow}n{p}_{3/2}, {n}^{\ensuremath{'}}{d}_{j}\ensuremath{\leftarrow}n{p}_{3/2}, {n}^{\ensuremath{'}}{f}_{{j}^{\ensuremath{'}}}\ensuremath{\leftarrow}n{d}_{j}$, and ${n}^{\ensuremath{'}}{g}_{{j}^{\ensuremath{'}}}\ensuremath{\leftarrow}n{f}_{j}$ and two-photon transitions $n{f}_{{j}^{\ensuremath{'}}}\ensuremath{\leftarrow}n{p}_{j}$ determined by millimeter-wave spectroscopy, where $j$ is the total angular-momentum quantum number. By combining the results from the laser and millimeter-wave spectroscopic experiments, we obtain improved values for the quantum defects of the ${s}_{1/2}, {d}_{3/2}, {d}_{5/2}, {f}_{j}$, and ${g}_{j}$ states. For the ${d}_{j}$ series, the inverted fine structure was confirmed for $n\ensuremath{\ge}32$. The fine-structure splitting of the $f$ series is less than 100 kHz at $n=31$, significantly smaller than the hydrogenic splitting, and the fine structure of the $g$ series is regular for $n\ensuremath{\ge}30$, with a fine-structure splitting compatible with the hydrogenic prediction. From the measured quantum defects of the $f$ and $g$ series we derive an estimate for the static dipole ${\ensuremath{\alpha}}_{\mathrm{d}}$ and quadrupole ${\ensuremath{\alpha}}_{\mathrm{q}}$ polarizabilities of the ${\mathrm{K}}^{+}$ ion core. Additionally, the hyperfine splitting of the $4{s}_{1/2}$ ground state of $^{39}\mathrm{K}$ was determined to be 461.719700(5) MHz using radio-frequency spectroscopy and Ramsey-type interferometry.

The aim of the study was to investigate DNA double-strand break (DSB) formation and its correlation to the absorbed dose to the blood in patients with surgically treated differentiated thyroid cancer undergoing their first radioiodine therapy for remnant ablation. Methods: Twenty patients were included in this study. At least 7 peripheral blood samples were obtained before and between 0.5 and 120 h after administration of radioiodine. From the time–activity curves of the blood and the whole body, residence times for the blood self-irradiation and the irradiation from the whole body were determined. Peripheral blood lymphocytes were isolated, ethanol-fixed, and subjected to immunofluorescence staining for colocalizing γ-H2AX/53BP1 DSB-marking foci. The average number of DSB foci per cell per patient sample was analyzed as a function of the absorbed dose to the blood and compared with an in vitro calibration curve for 131I and 177Lu established previously in our institution. Results: The average number of radiation-induced foci (RIF) per cell increased over the first 3 h after radionuclide administration and decreased thereafter. A linear fit from 0 to 2 h as a function of the absorbed dose to the blood agreed with our in vitro calibration curve. At later time points, RIF numbers diminished, along with dropping dose rates, indicating progression of DNA repair. Individual patient data were characterized by a linear dose-dependent increase and a biexponential response function describing a fast and a slow repair component. Conclusion: With the experimental results and model calculations presented in this work, a dose–response relationship is demonstrated, and an analytic function describing the time course of the in vivo damage response after internal irradiation of patients with 131I is established.

Normally-on wide bandgap power semiconductor devices such as SiC JFET or GaN HFET demonstrate great promise for future power electronics applications, but suffer from power bus shoot-through concerns. This paper investigates new gate drive techniques to make the normally-on WBG devices inherently safe against potential power bus shoot-through failures. A fast-acting startup lockup protection circuit is proposed to derive power directly from the DC bus and generate a negative voltage to hold the WBG device in OFF mode. Simulation and experiment results show that the startup lockup source could generate −12V voltage within a few μs.

Research library structures have grown in size and complexity over the past several decades. There is no single template for how to organize a library in the 21st century, but it is unclear how much variance in structure truly exists between libraries. This study sought to identify the essential features and characteristics of these structures through the collection and analysis of organization charts. Specifically, this study analyzes the roles and position of senior leaders (e.g. Associate University Librarians, Associate Deans, etc.) as well as how scholarly communications activities are positioned within research libraries. Findings indicate wide variance in the structure of senior leadership roles as well as how a relatively recent library function fits with other units.