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Université de Fribourg

Signatures of bosonic excitations in high-harmonic spectra of Mott insulators

Lysne, Markus ; Murakami, Yuta ; Werner, Philipp

In: Physical Review B, 2020, vol. 101, no. 19, p. 195139

The high-harmonic spectrum of the Mott insulating Hubbard model has recently been shown to exhibit plateau structures with cutoff energies determined by nth-nearest- neighbor doublon-holon recombination processes. The spectrum thus allows one to extract the on-site repulsion U. Here, we consider generalizations of the single-band Hubbard model and discuss the signatures of bosonic excitations...

Université de Fribourg

Adsorption-induced kondo effect in metal-free phthalocyanine on Ag(111)

Granet, J. ; Sicot, M. ; Gerber, I. C. ; Kremer, Geoffroy ; Pierron, T. ; Kierren, B. ; Moreau, L. ; Fagot-Revurat, Y. ; Lamare, S. ; Chérioux, F. ; Malterre, D.

In: The Journal of Physical Chemistry C, 2020, vol. 124, no. 19, p. 10441–10452

We report on the formation of a two-dimensional supramolecular Kondo lattice made of organic molecules comprising only C, N, and H atoms, namely metal-free phthalocyanines 2HPc (C32H18N8), adsorbed on a Ag(111) surface. Low-temperature scanning tunneling microscopy/spectroscopy (LT-STM/STS), ultraviolet photoemission spectroscopy (UPS), and density functional theory (DFT) are used to...

Université de Fribourg

A new species of Palaeopython (Serpentes) and other extinct squamates from the Eocene of Dielsdorf (Zurich, Switzerland)

Georgalis, Georgios L. ; Scheyer, Torsten M.

In: Swiss Journal of Geosciences, 2019, vol. 112, no. 2, p. 383–417

The lizard and snake fauna from the late middle–late Eocene (MP 16–MP 20) of Dielsdorf, near Zurich, Switzerland, is described comprehensively in this paper. Detailed comparisons of the Dielsdorf material with other extinct taxa allow us to establish a new species of the large “booid” genus Palaeopython, i.e., Palaeopython helveticus sp. nov., characterized by a unique combination of...

Université de Fribourg

Coupling of electronic and nuclear motion in a negative ion resonance: Experimental and theoretical study of benzene

Allan, Michael ; Čurík, Roman ; Čársky, Petr

In: The Journal of Chemical Physics, 2019, vol. 151, no. 6, p. 064119

We present calculated and measured elastic and vibrational excitation cross sections in benzene with the objective to assess the reliability of the theoretical method and to shed more light on how the electronic motion of the incoming electron is coupled with the nuclear motion of the vibrations. The calculation employed the discrete momentum representation method which involves solving the...

Université de Fribourg

High-harmonic generation in quantum spin systems

Takayoshi, Shintaro ; Murakami, Yuta ; Werner, Philipp

In: Physical Review B, 2019, vol. 99, no. 18, p. 184303

We theoretically study the high-harmonic generation (HHG) in one-dimensional spin systems. While in electronic systems the driving by ac electric fields produces radiation from the dynamics of excited charges, we consider here the situation where spin systems excited by a magnetic field pulse generate radiation via a time- dependent magnetization. Specifically, we study the magnetic dipole...

Université de Fribourg

Sympatric diploid and tetraploid cytotypes of Centaurea stoebe s.l. do not differ in arbuscular mycorrhizal communities and mycorrhizal growth response

Sudová, Radka ; Kohout, Petr ; Kolaříková, Zuzana ; Rydlová, Jana ; Voříšková, Jana ; Suda, Jan ; Španiel, Stanislav ; Müller-Schärer, Heinz ; Mráz, Patrik

In: American Journal of Botany, 2018, vol. 105, no. 12, p. 1995–2007

Genome duplication is associated with multiple changes at different levels, including interactions with pollinators and herbivores. Yet little is known whether polyploidy may also shape belowground interactions.Methods: To elucidate potential ploidy‐specific interactions with arbuscular mycorrhizal fungi (AMF), we compared mycorrhizal colonization and assembly of AMF communities in roots of...

Université de Fribourg

Dissociative electron attachment and electronic excitation in Fe(CO)5

Allan, Michael ; Lacko, M. ; Papp, P. ; Matejčík, Š. ; Zlatar, Matija ; Fabrikant, Ilya I. ; Kočišek, J. ; Fedor, Juraj

In: Physical Chemistry Chemical Physics, 2018, vol. 20, no. 17, p. 11692–11701

In a combined experimental and theoretical study we characterize dissociative electron attachment (DEA) to, and electronically excited states of, Fe(CO)5. Both are relevant for electron-induced degradation of Fe(CO)5. The strongest DEA channel is cleavage of one metal–ligand bond that leads to production of Fe(CO)4−. High- resolution spectra of Fe(CO)4− reveal fine structures at the...