Double-electron ionization driven by inhomogeneous fields

Authors may self-archive the author’s accepted manuscript of their articles on their own websites. Authors may also deposit this version of the article in any repository, provided it is only made publicly available 12 months after official publication or later. He/ she may not use the publisher's version (the final article), which is posted on SpringerLink and other Springer websites, for the purpose of self-archiving or deposit. Furthermore, the author may only post his/her version provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be provided by inserting the DOI number of the article in the following sentence: “The final publication is available at Springer via https://link.springer.com/article/10.1007/s00340-017-6672-4"Electron–electron correlation effects play a crucial role in our understanding of sequential (SDI) and non-sequential double ionization (NSDI) mechanisms. Here, we present a theoretical study of NSDI driven by plasmonic-enhanced spatial inhomogeneous fields. By numerically solving the time-dependent Schrödinger equation for a linear reduced model of He and a double-electron time-evolution probability analysis, we provide evidence for enhancement effects in NSDI showing that the double ionization yield at lower laser peak intensities is increased due to the spatial inhomogeneous character of plasmonic-enhanced field. The change in the emission direction of the double-ion as a function of the field inhomogeneity degree demonstrates that plasmonic-enhanced fields could configure a reliable instrument to control the ion emission. Furthermore, our quantum mechanical model, as well as classical trajectory Monte Carlo simulations, show that inhomogeneous fields are as well as a useful tool for splitting the binary and recoil processes in the rescattering scenario.This work was supported by the project ELI-Extreme Light Infrastructure-phase 2 (Project No. CZ.02.1.01/0.0/0.0/ 15_008/0000162) from European Regional Development Fund, Spanish MINECO (National Plan grants FIS2011-30465-C02-01, FOQUS No. FIS2013-46768-P, FISICATEAMO FIS2016-79508-P and Severo Ochoa Excellence Grant No. SEV-2015-0522), the Generalitat de Catalunya (SGR 874 and CERCA/Program) and Fundació Privada Cellex Barcelona. N.S. was supported by the Erasmus Mundus Doctorate Program Europhotonics (Grant No. 159224-1-2009-1-FR-ERA MUNDUS-EMJD). N.S., A.C., and M.L. acknowledge ERC AdG OSYRIS, EU FETPRO QUIC and National Science Centre, Poland—Symfonia Grant 2016/20/W/ST4/00314. A. S. L. acknowledges Max Planck Center for Attosecond Science (MPC-AS). J. A. P.-H. acknowledges to the Spanish Ministerio de Economía y Competitivi- dad (FURIAM Project No. FIS2013-47741-R and PALMA project FIS2016- 81056-R) and Laserlab-Europe (EU-H2020 654148). L.O. acknowledges valuable input from Andre Staudte. The authors thankfully acknowledge the computer resources at MareNostrum, technical expertise and assistance provided by the Barcelona Supercomputing Center and the Red Española de Supercomputación (RES)Peer ReviewedPostprint (author's final draft

Polar Field Reversal Observations with Hinode

We have been monitoring yearly variation in the Sun's polar magnetic fields with the Solar Optical Telescope aboard {\it Hinode} to record their evolution and expected reversal near the solar maximum. All magnetic patches in the magnetic flux maps are automatically identified to obtain the number density and magnetic flux density as a function of th total magnetic flux per patch. The detected magnetic flux per patch ranges over four orders of magnitude ($10^{15}$ -- $10^{20}$ Mx). The higher end of the magnetic flux in the polar regions is about one order of magnitude larger than that of the quiet Sun, and nearly that of pores. Almost all large patches ($\geq 10^{18}$ Mx) have the same polarity, while smaller patches have a fair balance of both polarities. The polarity of the polar region as a whole is consequently determined only by the large magnetic concentrations. A clear decrease in the net flux of the polar region is detected in the slow rising phase of the current solar cycle. The decrease is more rapid in the north polar region than in the south. The decrease in the net flux is caused by a decrease in the number and size of the large flux concentrations as well as the appearance of patches with opposite polarity at lower latitudes. In contrast, we do not see temporal change in the magnetic flux associated with the smaller patches ($< 10^{18}$ Mx) and that of the horizontal magnetic fields during the years 2008--2012.Comment: 21 pages, 7 figures. Accepted for publication in Ap

Quiet Sun magnetic fields from space-borne observations: simulating Hinode's case

We examine whether or not it is possible to derive the field strength distribution of quiet Sun internetwork regions from very high spatial resolution polarimetric observations in the visible. In particular, we consider the case of the spectropolarimeter attached to the Solar Optical Telescope aboard Hinode. Radiative magneto-convection simulations are used to synthesize the four Stokes profiles of the \ion{Fe}{1} 630.2 nm lines. Once the profiles are degraded to a spatial resolution of 0\farcs32 and added noise, we infer the atmospheric parameters by means of Milne-Eddington inversions. The comparison of the derived values with the real ones indicates that the visible lines yield correct internetwork field strengths and magnetic fluxes, with uncertainties smaller than $\sim$150 G, when a stray light contamination factor is included in the inversion. Contrary to the results of ground-based observations at 1\arcsec, weak fields are retrieved wherever the field is weak in the simulation.Comment: Accepted for publication in ApJ Letter

CNO behaviour in planet-harbouring stars. II. Carbon abundances in stars with and without planets using the CH band

Context. Carbon, oxygen and nitrogen (CNO) are key elements in stellar formation and evolution, and their abundances should also have a significant impact on planetary formation and evolution. Aims. We present a detailed spectroscopic analysis of 1110 solar-type stars, 143 of which are known to have planetary companions. We have determined the carbon abundances of these stars and investigate a possible connection between C and the presence of planetary companions. Methods. We used the HARPS spectrograph to obtain high-resolution optical spectra of our targets. Spectral synthesis of the CH band at 4300\AA was performed with the spectral synthesis codes MOOG and FITTING. Results. We have studied carbon in several reliable spectral windows and have obtained abundances and distributions that show that planet host stars are carbon rich when compared to single stars, a signature caused by the known metal-rich nature of stars with planets. We find no different behaviour when separating the stars by the mass of the planetary companion. Conclusions. We conclude that reliable carbon abundances can be derived for solar-type stars from the CH band at 4300\AA. We confirm two different slope trends for [C/Fe] with [Fe/H] because the behaviour is opposite for stars above and below solar values. We observe a flat distribution of the [C/Fe] ratio for all planetary masses, a finding that apparently excludes any clear connection between the [C/Fe] abundance ratio and planetary mass.Comment: 10 pages, 10 figures. Accepted to A&

C/O vs Mg/Si ratios in solar type stars: The HARPS sample

Aims. We present a detailed study of the Mg/Si and C/O ratios and their importance in determining the mineralogy of planetary companions. Methods. Using 499 solar-like stars from the HARPS sample, we determine C/O and Mg/Si elemental abundance ratios to study the nature of the possible planets formed. We separated the planetary population in low-mass planets ( < 30 $\rm M_{\odot}$) and high-mass planets ( > 30 $\rm M_{\odot}$) to test for possible relation with the mass. Results. We find a diversity of mineralogical ratios that reveal the different kinds of planetary systems that can be formed, most of them dissimilar to our solar system. The different values of the Mg/Si and C/O ratios can determine different composition of planets formed. We found that 100\% of our planetary sample present C/O < 0.8. 86\% of stars with high-mass companions present 0.8 > C/O > 0.4, while 14\% present C/O values lower than 0.4. Regarding Mg/Si, all stars with low-mass planetary companion showed values between 1 and 2, while 85% of the high-mass companion sample does. The other 15\% showed Mg/Si values below 1. No stars with planets were found with Mg/Si > 2. Planet hosts with low-mass companions present C/O and Mg/Si ratios similar to those found in the Sun, whereas stars with high-mass companions have lower C/O.Comment: 9 pages, 12 figues. Accepted in A&

Consumer-brand relationships under the marketing 3.0 paradigm: A literature review

Consumer-brand relationships encompass several dimensions, most of which have attracted growing research attention during the last years. Building these relationships is especially important in the marketing 3.0 era, where it is suggested that customers will choose those brands that satisfy their deepest needs. With these ideas in mind, this article provides a review of two key concepts implied in such relationships: brand love and customer engagement. Although both conceptions focus on different stages of consumer-brand relationships, they actually cover different perspectives on the same process. Moreover, they come from diverse conceptual paradigms: whilst brand love comes from the psychology discipline, engagement derives from diverse areas of the marketing field (e.g., the service-dominant logic perspective). However, their further empirical developments have taken place in marketing. Besides, both terms appear to be applied to different empirical perspectives: brand love is usually linked to the Fast Moving Consumer Goods industry and customer engagement to services