| 1. |
- Aziz, Emad F., et al.
(författare)
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Photoinduced formation of N-2 molecules in ammonium compounds
- 2007
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 111:39, s. 9662-9669
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Tidskriftsartikel (refereegranskat)abstract
- Via fluorescence yield (FY) and resonant inelastic scattering spectroscopy in the soft X-ray range we find that soft X-rays induce formation of N-2 molecules in solid NH4Cl and in related compounds. The nitrogen molecules form weak bonds in NH4Cl, so that a substantial fraction of the molecules remains in the sample. From measurements of the FY as a function of exposure and temperature, the rates for the photochemical processes are estimated. At elevated temperatures (363 K), several nitrogen atoms are removed from the sample per incoming photon. At lower temperatures (233 K), the rate is reduced to around 0.02 nitrogen atoms for each incoming photon. Virtually all these atoms form N-2 molecules which are bound in the sample. The generality and implications of these results are briefly discussed.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Jana, Somnath, et al.
(författare)
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Analysis of the linear relationship between asymmetry and magnetic moment at the M edge of 3d transition metals
- 2020
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Ingår i: Physical Review Research. - : American Physical Society. - 2643-1564. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- The magneto-optical response of Fe and Ni during ultrafast demagnetization is studied experimentally and theoretically. We have performed pump-probe experiments in the transverse magneto-optical Kerr effect (T-MOKE) geometry using photon energies that cover the M absorption edges of Fe and Ni between 40 and 72 eV. The magnetic asymmetry was obtained by forming the difference of reflected intensities obtained for two opposite orientations of the sample magnetization. Density functional theory (DFT) was used to calculate the magneto-optical response of different magnetic configurations, representing different types of excitations: long wavelength magnons, short wavelength magnons, and Stoner excitations. In the case of Fe, we find that the calculated asymmetry is strongly dependent on the specific type of magnetic excitation. Our modeling also reveals that during remagnetization Fe is, to a reasonable approximation, described by magnons, even though small nonlinear contributions could indicate some degree of Stoner excitations as well. In contrast, we find that the calculated asymmetry in Ni is rather insensitive to the type of magnetic excitations. However, there is a weak nonlinearity in the relation between asymmetry and the off-diagonal component of the dielectric tensor, which does not originate from the modifications of the electronic structure. Our experimental and theoretical results thus emphasize the need to consider a coupling between asymmetry and magnetization that may be more complex than a simple linear relationship. This insight is crucial for the microscopic interpretation of ultrafast magnetization experiments.
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| 6. |
- Jana, Somnath, et al.
(författare)
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Atom-specific magnon driven ultrafast spin dynamics in Fe1-xNix alloys
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- By employing element specific ultrafast spectroscopy in Fe1-xNix alloys alloys, we find a composition dependent effect in the demagnetization that we relate to changes in electron-magnon scattering. In all six measured alloys of different composition, the demagnetization of Ni compared to Fe exhibits a delay, an effect which we find is inherent in alloys but not in elemental Fe and Ni. Using a model based on electron-magnon scattering, we extract a spin-wave stiffness from all alloys that show excellent agreement with values obtained from other techniques. The result establishes the atom-specific sd-exchange induced magnon generation as an underlying mechanism during ultrafast demagnetization in Fe1-xNix alloys
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| 7. |
- Jana, Somnath, et al.
(författare)
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Atom-specific magnon-driven ultrafast spin dynamics in Fe1-xNix alloys
- 2023
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 107:18
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Tidskriftsartikel (refereegranskat)abstract
- By employing element-specific spectroscopy in the ultrafast time scale in Fe1-xNix alloys, we find a composition-dependent effect in the demagnetization that we relate to electron-magnon scattering and changes in the spin-wave stiffness. In all six measured alloys of different composition, the demagnetization of Ni compared to Fe exhibits a delay, an effect which we find is inherent in alloys but not in elemental Fe and Ni. Using a model based on electron-magnon scattering, we extract a spin-wave stiffness from all alloys that show excellent agreement with values obtained from other techniques.
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| 8. |
- Locht, Inka L. M., 1986-, et al.
(författare)
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Magnetic asymmetry around the 3p absorption edge in Fe and Ni
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This work is a joint theoretical and experimental study of the relation between the magneto- optical response of a material in the sub-picosecond timescale and its instantaneous magnetisation. We perform pump-probe experiments in the transverse magneto-optical Kerr effect (T-MOKE) geometry. We measure the magnetic asymmetry of elemental Fe and Ni before and after the laser pulse. The observed differences between the magnetic asymmetry curves for various photon energies suggest that the relation between asymmetry and sample magnetization is more complex than a simple proportionality. Further insight is obtained by means of theoretical simulations based on density-functional theory. Our calculations show that non-linear effects in the asymmetry are most prominent at energies corresponding to the absorption edge and that the proportionality is recovered outside of this region. In conclusion, our experimental and theoretical results emphasize the need of including the complex relation between asymmetry and magnetization in the interpretation of ultrafast magnetization experiments in terms of microscopic properties.
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| 9. |
- Rubensson, Jan-Erik, et al.
(författare)
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Rydberg-Resolved Resonant Inelastic Soft X-Ray Scattering: Dynamics at Core Ionization Thresholds
- 2015
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 114:13
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Tidskriftsartikel (refereegranskat)abstract
- Resonant inelastic x-ray scattering spectra excited in the immediate vicinity of the core-level ionization thresholds of N-2 have been recorded. Final states of well-resolved symmetry-selected Rydberg series converging to valence-level ionization thresholds with vibrational excitations are observed. The results are well described by a quasi-two-step model which assumes that the excited electron is unaffected by the radiative decay. This threshold dynamics simplifies the interpretation of resonant inelastic x-ray scattering spectra considerably and facilitates characterization of low-energy excited final states in molecular systems.
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| 10. |
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| 11. |
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| 12. |
- Wasenius, Niko S, et al.
(författare)
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Low-cost exercise interventions improve long-term cardiometabolic health independently of a family history of type 2 diabetes : a randomized parallel group trial
- 2020
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Ingår i: BMJ open diabetes research & care. - : BMJ. - 2052-4897. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: To investigate the effect of an exercise prescription and a 1-year supervised exercise intervention, and the modifying effect of the family history of type 2 diabetes (FH), on long-term cardiometabolic health.RESEARCH DESIGN AND METHODS: For this prospective randomized trial, we recruited non-diabetic participants with poor fitness (n=1072, 30-70 years). Participants were randomly assigned with stratification for FH either in the exercise prescription group (PG, n=144) or the supervised exercise group (EG, n=146) group and compared with a matched control group from the same population study (CON, n=782). The PG and EG received exercise prescriptions. In addition, the EG attended supervised exercise sessions two times a week for 60 min for 12 months. Cardiometabolic risk factors were measured at baseline, 1 year, 5 years, and 6 years. The CON group received no intervention and was measured at baseline and 6 years.RESULTS: The EG reduced their body weight, waist circumference, diastolic blood pressure, and low-density lipoprotein-cholesterol (LDL-C) but not physical fitness (p=0.074) or insulin or glucose regulation (p>0.1) compared with the PG at 1 year and 5 years (p≤0.011). The observed differences were attenuated at 6 years; however, participants in the both intervention groups significantly improved their blood pressure, high-density lipoprotein-cholesterol, and insulin sensitivity compared with the population controls (p≤0.003). FH modified LDL-C and waist circumference responses to exercise at 1 year and 5 years.CONCLUSIONS: Low-cost physical activity programs have long-term beneficial effects on cardiometabolic health regardless of the FH of diabetes. Given the feasibility and low cost of these programs, they should be advocated to promote cardiometabolic health.TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier NCT02131701.
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| 13. |
- Zackrisson, Björn, et al.
(författare)
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Mature results from a Swedish comparison study of conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma - The ARTSCAN trial
- 2015
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 117:1, s. 99-105
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: This report contains the mature five-year data from the Swedish ARTSCAN trial including information on the influence of p16 positivity (p16+) for oropharyngeal cancers. Material and methods: Patients with previously untreated squamous cell carcinoma without distant metastases of the oral cavity, oropharynx, larynx (except T1-2, NO glottic cancers) and hypopharynx were included. Patients were randomised between accelerated fractionation (AF) (1.1 Gy + 2 Gy per day, 5 days/week for 4.5 weeks, total dose 68 Gy) and conventional fractionation (CF) (2 Gy per day, 5 days/week for 7 weeks, total dose 68 Gy). Human papillomavirus (HPV)-associated p16-expression was assessed retrospectively in tumour tissues from patients with oropharyngeal carcinoma. Results: There was no significant difference in loco-regional control (LRC) between AF and CF (log-rank test p = 0.75). LRC at 5 years was 65.5% for AF and 64.9% for CF. Overall survival (OS) was similar in both arms (p = 0.99). The estimated cancer specific survival (CSS) at 5 years was 62.2% (AF) and 63.3% (CF) (p = 0.99). 206 specimens were analysed for p16 with 153 specimens (74%) identified as p16+. P16 status did not discriminate for response to AF vs. CF with regard to LRC, OS or CSS. Patients with p16+ tumours had a statistically significant better overall prognosis compared with p16 tumours. Conclusion: This update confirms the results of the 2-year report. We failed to identify a positive effect resulting from AF with regards to LRC, OS and CSS. The addition of information on the HPV-associated p16 overexpression did not explain this lack of effect.
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| 14. |
- Agåker, Marcus, et al.
(författare)
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Resonant inelastic soft x-ray scattering at double core excitations in solid LiCl
- 2006
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:24
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Tidskriftsartikel (refereegranskat)abstract
- Inelastic soft x-ray scattering in LiCl, resonantly enhanced at states with two Li 1s vacancies, is investigated. States in which both excited electrons are localized during the double core hole lifetime, in which one of the electrons delocalize, as well as triply excited states in which the double core excitation is accompanied by a valence-to-conduction band excitation, contribute to the scattering. The angular momentum symmetry of the involved states and the vibronic coupling during the scattering process are reflected in the angular anisotropy. The effect on the local electronic structure of multiple core holes is theoretically studied by means of supercell band calculations.
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| 15. |
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| 16. |
- Akkoyun, S., et al.
(författare)
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AGATA - Advanced GAmma Tracking Array
- 2012
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 0167-5087 .- 1872-9576. ; 668, s. 26-58
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Tidskriftsartikel (refereegranskat)abstract
- The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector- response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer. © 2011 Elsevier B.V. All rights reserved.
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| 17. |
- Alagia, M, et al.
(författare)
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Angular effects in autoionization of 3 P doubly excited states in He
- 2009
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Ingår i: Journal of Physics: Conference Series. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- The first members of dipole allowed 3 P o doubly excited series in helium have been observed in resonant photoexcitation of 1 s 2 s 3 S e metastable atoms. A good agreement measured relative photoionization cross sections is achieved when theory includes the radiation damping and, also important, the effects of spin-orbit multiplet splitting on electron angular distribution.
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| 18. |
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| 19. |
- Alagia, M., et al.
(författare)
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Excitation of 1S and 3S Metastable Helium Atoms to Doubly Excited States
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:15, s. 153001-
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Tidskriftsartikel (refereegranskat)abstract
- We present spectra of triplet and singlet metastable helium atoms resonantly photoexcited to doubly excited states. The first members of three dipole-allowed 1,3Po series have been observed and their relative photoionization cross sections determined, both in the triplet (from 1s2s 3Se) and singlet (from 1s2s 1Se) manifolds. The intensity ratios are drastically different with respect to transitions from the ground state. When radiation damping is included the results for the singlets are in agreement with theory, while for triplets spin-orbit interaction must also be taken into account.
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| 20. |
- Backes, Carl, et al.
(författare)
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Outcomes Following a Comprehensive versus a Selective Approach for Infants Born at 22 Weeks of Gestation.
- 2019
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Ingår i: Journal of Perinatology. - : Springer Science and Business Media LLC. - 0743-8346 .- 1476-5543. ; 39:1, s. 39-47
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To examine outcomes at two institutions with different approaches to care among infants born at 22 weeks of gestation.Study design: Retrospective, cohort study (2006–2015). Enrollment was limited to mother–infant dyads at 22 weeks of gestation. Proactive care was defined as provision of antenatal corticosteroids and neonatal resuscitation and intensive care. One center (Uppsala, Sweden; UUCH) provided proactive care to all mother–infant dyads (comprehensive center); the other center (Nationwide Children’s Hospital, USA; NCH) initiated or withheld treatment based on physician and family preferences (selective center). Differences in outcomes between the two centers were evaluated.Result: Among 112 live-born infants at 22 weeks of gestation, those treated at UUCH had in-hospital survival rates higher than those at NCH (21/40, 53% vs. 6/72, 8%; P < 0.01). Among the subgroup of infants receiving proactive care (UUCH: 40/40, 100%; NCH: 16/72, 22%) survival was higher at UUCH than at NCH (21/40, 53% vs. 3/16, 19%; P < 0.05).Conclusion: Even when mother–infant dyads were provided proactive care at NCH (selective center), survival was lower than infants provided proactive care at UUCH (comprehensive center). Differences between the approaches to care at the two centers at 22 weeks of gestation merits further investigation.
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| 21. |
- Backlund, Sandra
(författare)
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Efficient improvement of energy efficiency in small and medium- sized Swedish firms
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This is a dissertation about efficient implementation of energy efficiency measures in small and medium-sized Swedish firms. The aim is to investigate the potential for economically efficient implementation of energy efficiency improvement measures in small and medium-sized firms. The thesis contains five papers that analyse different aspects that have been put forth in policy documents and academic debate as methods to improve energy efficiency in non-energy intensive sectors.By reading policy documents, interviewing representatives of small and medium- sized firms and energy auditors as well as analysing data from the Swedish energy audit program, different aspects of energy management practices, energy services and energy audits are considered. The thesis is the product of an interdisciplinary context but economic theory is at the foundation of the analysis and has helped formulate questions and hypotheses that have been tested and explored with the data.The results show that while the potential for improving energy efficiency in the small and medium- sized sector in Sweden is large there are challenges to realizing it in each individual firm. There is potential for improving energy efficiency in the sector and not just for investments in new technology but also for adjusting existing machinery and changing behaviour, but costs for investigating the potential and implementing the measures are large relative to the improvement potential in each company. Energy management practices in this sector are lacking and energy services will only be demanded if reduction in production cost is estimated larger than transaction costs of the service. The Swedish energy audit program has led to the implementation of energy efficiency improvements in the participating firms but compared to other policy instruments it has been a less cost-efficient way to improve energy efficiency in Sweden.
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| 22. |
- Berholts, Marta, et al.
(författare)
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Quantum watch and its intrinsic proof of accuracy
- 2022
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Ingår i: Physical Review Research. - : American Physical Society. - 2643-1564. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the rich dynamics of complex wave packets composed of multiple high-lying Rydbergstates in He. A quantitative agreement is found between theory and time-resolved photoelectron spectroscopyexperiments. We show that the intricate time dependence of such wave packets can be used for investigatingquantum defects and performing artifact-free timekeeping. The latter relies on the unique fingerprint that iscreated by the time-dependent photoionization of these complex wave packets. These fingerprints determinehow much time has passed since the wave packet was formed and provide an assurance that the measured time iscorrect. Unlike any other clock, this quantum watch does not utilize a counter and is fully quantum mechanicalin its nature. The quantum watch has the potential to become an invaluable tool in pump-probe spectroscopy dueto its simplicity, assurance of accuracy, and ability to provide an absolute timestamp, i.e., there is no need to findtime zero.
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| 23. |
- Björneholm, Olle, et al.
(författare)
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Deeper Insight into Depth-Profiling of Aqueous Solutions Using Photoelectron Spectroscopy
- 2014
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:50, s. 29333-29339
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Tidskriftsartikel (refereegranskat)abstract
- X-ray photoelectron spectroscopy (XPS) is widely used to probe properties such as molecular stoichiometry, microscopic distributions relative to the surface by so-called depth-profiling, and molecular orientation. Such studies usually rely on the core-level photoionization cross sections being independent of molecular composition. The validity of this assumption has recently been questioned, as a number of gas-phase molecules have been shown to exhibit photon-energy-dependent nonstochiometric intensity oscillations arising from EXAFS-like modulations of the photoionization cross section. We have studied this phenomenon in trichloroethanol in both gas phase and dissolved in water. The gas-phase species exhibits pronounced intensity oscillations, similar to the ones observed for other gas-phase molecules. These oscillations are also observed for the dissolved species, implying that the effect has to be taken into account when performing depth-profiling experiments of solutions and other condensed matter systems. The similarity between the intensity oscillations for gas phase and dissolved species allows us to determine the photoelectron kinetic energy of maximum surface sensitivity, approximate to 100 eV, which lies in the range of pronounced intensity oscillations.
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| 24. |
- Boutachkov, P., et al.
(författare)
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High-spin isomers in 96Ag : excitations across the Z=38 and Z=50, N=50 closed shells
- 2011
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 84:4
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Tidskriftsartikel (refereegranskat)abstract
- Excited states in (96)Ag were populated in fragmentation of an 850-MeV/u (124)Xe beam on a 4-g/cm(2) Be target. Three new high-spin isomers were identified and the structure of the populated states was investigated. The level scheme of (96)Ag was established, and a spin parity of (13(-)), (15(+)), and (19(+)) was assigned to the new isomeric states. Shell-model calculations were performed in various model spaces, including pi nu(p(1/2), g(9/2), f(5/2), p(3/2)) and the large-scale shell-model space pi nu(gds), to account for the observed parity changing M2 and E3 transitions from the (13(-)) isomer and the E2 and E4 transitions from the (19(+)) core-excited isomer, respectively. The calculated level schemes and reduced transition strengths are found to be in very good agreement with the experiment.
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| 25. |
- Boutachkov, P., et al.
(författare)
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Isomer and Beta-decay Spectroscopy of Tz=1 Isotopes Below the N=Z=50 Shell Gap
- 2011
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 312:9
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Tidskriftsartikel (refereegranskat)abstract
- The RISING setup at the GSI-FRS facility was used to investigate the isomer and beta decays in N~Z~50 Cd, Ag and Pd isotopes. A preliminary analysis of the data has revealed new results on the Tz=1, 94Pd, 96Ag and 98Cd isotopes. In 94Pd a new high-spin isomer was observed, whilst in 96Ag 3 new isomeric states were identified, including core-excited states. In 98Cd a new high-energy isomeric γ-ray transition is observed, thus enabling us to confirm the previous spin assignment for the core-excited 12+ isomer.
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