| 1. |
- Busto, David, et al.
(författare)
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Fano's Propensity Rule in Angle-Resolved Attosecond Pump-Probe Photoionization
- 2019
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 123:13
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Tidskriftsartikel (refereegranskat)abstract
- In a seminal article, Fano predicts that absorption of light occurs preferably with increase of angular momentum. We generalize Fano's propensity rule to laser-assisted photoionization, consisting of absorption of an extreme-ultraviolet photon followed by absorption or emission of an infrared photon. The predicted asymmetry between absorption and emission leads to incomplete quantum interference in attosecond photoelectron interferometry. It explains both the angular dependence of the photoionization time delays and the delay dependence of the photoelectron angular distributions. Our theory is verified by experimental results in Ar in the 20-40 eV range.
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| 2. |
- Petersson, C. L.M., et al.
(författare)
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Anisotropic photoemission time delays close to a Fano resonance
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Electron correlation and multielectron effects are fundamental interactions that govern many physical and chemical processes in atomic, molecular and solid state systems. The process of autoionization, induced by resonant excitation of electrons into discrete states present in the spectral continuum of atomic and molecular targets, is mediated by electron correlation. Here we investigate the attosecond photoemission dynamics in argon in the 20-40 eV spectral range, in the vicinity of the 3s(-1)np autoionizing resonances. We present measurements of the differential photoionization cross section and extract energy and angle-dependent atomic time delays with an attosecond interferometric method. With the support of a theoretical model, we are able to attribute a large part of the measured time delay anisotropy to the presence of autoionizing resonances, which not only distort the phase of the emitted photoelectron wave packet but also introduce an angular dependence.
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| 3. |
- Zhong, Shiyang, et al.
(författare)
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Attosecond electron–spin dynamics in Xe 4d photoionization
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- The photoionization of xenon atoms in the 70–100 eV range reveals several fascinating physical phenomena such as a giant resonance induced by the dynamic rearrangement of the electron cloud after photon absorption, an anomalous branching ratio between intermediate Xe+ states separated by the spin-orbit interaction and multiple Auger decay processes. These phenomena have been studied in the past, using in particular synchrotron radiation, but without access to real-time dynamics. Here, we study the dynamics of Xe 4d photoionization on its natural time scale combining attosecond interferometry and coincidence spectroscopy. A time-frequency analysis of the involved transitions allows us to identify two interfering ionization mechanisms: the broad giant dipole resonance with a fast decay time less than 50 as, and a narrow resonance at threshold induced by spin-flip transitions, with much longer decay times of several hundred as. Our results provide insight into the complex electron-spin dynamics of photo-induced phenomena.
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| 4. |
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| 5. |
- Bertolino, Mattias, et al.
(författare)
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Multiphoton interaction phase shifts in attosecond science
- 2021
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Ingår i: Physical Review Research. - 2643-1564. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio simulations of a range of interferometric experiments are used to identify a strong dependence on multiphoton phase shifts in above-threshold ionization (ATI). A simple rule of thumb for interaction phase shifts is derived to explain both the conservation of photoelectron yield and its absolute CEP dependence. For instance, it is found that interferometric (ATI) experiments are shifted by π/4 relative to RABBIT experiments, and that there is no RABBIT term in a laser-assisted photoionization experiment with odd and even harmonics. Thus, our work helps to resolve the issues of interpretation of quantum dynamics in attosecond and free-electron laser sciences.
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| 6. |
- Bertolino, Mattias, et al.
(författare)
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Propensity rules and interference effects in laser-Assisted photoionization of helium and neon
- 2020
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 53:14
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the angle-resolved photoelectron spectra from laser-Assisted photoionization for helium and neon atoms using an ab initio method based on time-dependent surface flux and configuration interaction singles. We find that the shape of the distributions can be interpreted using a propensity rule, an intrinsic difference in the absorption and the emission processes, as well as interference effects between multiple paths to the final angular momentum state. The difference between absorption and emission is hidden in the first sideband in neon due to the multiple competing m channels, while in the second sideband a qualitative difference between absorption and emission is observed. In the m-resolved case, a clear difference is observed already in the first sideband, as exemplified in helium and m-resolved neon.
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| 7. |
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| 8. |
- Bertolino, Mattias, et al.
(författare)
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Thomas-Reiche-Kuhn correction for truncated configuration-interaction spaces : Case of laser-assisted dynamical interference
- 2022
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 106:4
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Tidskriftsartikel (refereegranskat)abstract
- The Thomas-Reiche-Kuhn sum rule is used to form an effective potential that is added to the time-dependent configuration-interaction singles (TDCIS) equations of motion in velocity gauge. The purpose of the effective potential is to include virtual coupling from singles to doubles, which is required for size-consistent velocity-gauge TDCIS results. The proposed method is compared to length-gauge TDCIS results for laser-assisted photoionization. Finally, a dynamical interference effect controlled by two-color fields is predicted for atomic targets.
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| 9. |
- Braunschweig, Frieder, et al.
(författare)
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New York Heart Association functional class, QRS duration, and survival in heart failure with reduced ejection fraction : implications for cardiac resychronization therapy.
- 2017
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Ingår i: European Journal of Heart Failure. - : Wiley-Blackwell. - 1388-9842 .- 1879-0844. ; 19:3, s. 366-376
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Symptom severity assessed by NYHA functional class and QRS duration are essential criteria for selection of heart failure (HF) patients for CRT. This study assessed the relationship between NYHA class, QRS duration, and survival in a nationwide HF registry.METHODS AND RESULTS: We studied 13 423 patients with HF in NYHA class II-IV and LVEF <40% in the Swedish Heart Failure Registry. Survival was followed via the Swedish Population Registry. Of 12 534 patients without CRT (age 71 ± 12 years, 29% women), 51% and 49% were in NYHA class II and III-IV, respectively. Patients in NYHA class II compared with class III-IV were younger (69 vs. 73 years), and had a better systolic function (49% vs. 58% with LVEF <30%), P <0.001 for all, and a favourable co-morbidity profile. QRS duration was 116 ± 29 ms in NYHA class II and 119 ± 29 ms in NYHA class III-IV with QRS ≥120 ms found in 37% vs. 44%, and an LBBB in 23% vs. 28% (P < 0.001 for all). Upon multivariable Cox regression adjusting for 40 clinically relevant variables, mortality risk was higher in NYHA class III-IV vs. class II, with a hazard ratio (HR) of 1.31, 95% confidence interval (CI) 1.23-1.40. Mortality was also higher with QRS prolongation ≥120 ms vs. narrow QRS. The HR in NYHA class II patients with non-LBBB was 1.19 (95% CI 1.05 - 1.36) and in those with LBBB it was 1.16 (95% CI 1.03-1.41). The corresponding HRs in NYHA class III-IV were 1.33 (95% CI 1.21-1.47) and 1.12 (95% CI 1.02-1.22). There was no significant interaction between the effects of NYHA class and QRS duration or morphology on mortality. Applying different scenarios to estimate guideline adherence, fewer patients with NYHA class II (range 14.4-42.6%) compared with NYHA class III-IV (18.0-45.4%) had received a CRT device when indicated.CONCLUSIONS: In HF with reduced LVEF, QRS prolongation is common and independently linked to worse survival. The increase in mortality risk associated with QRS prolongation of both LBBB and non-LBBB morphology is similar in NYHA class II and III-IV.
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| 10. |
- Brizuela, Fernando, et al.
(författare)
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Efficient high order harmonic generation boosted by below threshold harmonics
- 2013
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3
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Tidskriftsartikel (refereegranskat)abstract
- High-order harmonic generation (HHG) in gases has been established as an important technique for the generation of coherent extreme ultraviolet (XUV) pulses at ultrashort time scales. Its main drawback, however, is the low conversion efficiency, setting limits for many applications, such as ultrafast coherent imaging, nonlinear processes in the XUV range, or seeded free electron lasers. Here we introduce a novel scheme based on using below-threshold harmonics, generated in a seeding cell, to boost the HHG process in a generation cell, placed further downstream in the focused laser beam. By modifying the fundamental driving field, these low-order harmonics alter the ionization step of the nonlinear HHG process. Our dual-cell scheme enhances the conversion efficiency of HHG, opening the path for the realization of robust intense attosecond XUV sources.
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