Zobrazeno 1 - 10
of 200
pro vyhledávání: '"Klaus Reimann"'
Publikováno v:
Structural Dynamics, Vol 9, Iss 2, Pp 024501-024501-10 (2022)
Soft modes in crystals are lattice vibrations with frequencies that decrease and eventually vanish as the temperature approaches a critical point, e.g., a structural change due to a phase transition. In ionic para- or ferroelectric materials, the fre
Externí odkaz:
https://doaj.org/article/9d8534c3deee4776b6bbce7a46444952
Publikováno v:
New Journal of Physics, Vol 16, Iss 4, p 045016 (2014)
Resulting from the availability of improved sources, research in the terahertz (THz) spectral range has increased dramatically over the last decade, leading essentially to the disappearance of the so-called ‘THz gap’. While most work to date has
Externí odkaz:
https://doaj.org/article/8f0c62da2292448ebd666097f27daced
Publikováno v:
New Journal of Physics, Vol 15, Iss 2, p 025039 (2013)
Recent experimental progress has allowed for the implementation of nonlinear two-dimensional (2D) terahertz (THz) spectroscopy in the ultrafast time domain. We discuss the principles of this technique based on multiple phase-locked electric field tra
Externí odkaz:
https://doaj.org/article/671c802cacd344439c6ec5f1467b16f7
Autor:
Thomas Schmid, Torvid Feiler, Max Rautenberg, Ahmed Ghalgaoui, Franziska Emmerling, Dorothee Silbernagl, Beate Paulus, Adam A. L. Michalchuk, Heinz Sturm, Klaus Reimann, Biswajit Bhattacharya
Publikováno v:
Angewandte Chemie. 132:5602-5607
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::2d31e68575e25b0365cc3bb4080765a2
https://doi.org/10.1002/ange.201914798
https://doi.org/10.1002/ange.201914798
Autor:
Taehee Kang, Jia Zhang, Achintya Kundu, Klaus Reimann, Michael Woerner, Thomas Elsaesser, Bernard Gil, Guillaume Cassabois, Christos Flytzanis, Giorgia Fugallo, Michele Lazzeri, Ryan Page, Debdeep Jena
Publikováno v:
Conference on Lasers and Electro-Optics.
Nonequilibrium dynamics of transverse optical (TO) phonons in few-layer hexagonal boron nitride is studied in mid-infrared pump-probe experiments. TO phonons display a 1.2 ps lifetime and a transient redshift due to anharmonic coupling with low-frequ
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::cdcebd57b6698e8899fe0933c21f4fb7
https://doi.org/10.1364/cleo_qels.2022.fm1a.7
https://doi.org/10.1364/cleo_qels.2022.fm1a.7
Publikováno v:
Conference on Lasers and Electro-Optics.
We present ultrafast x-ray diffraction experiments of the underdamped soft mode in paraelectric KDP. Charge density maps derived from the x-ray data reveal oscillatory electronic charge relocations over interatomic distances, much larger than the sub
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::f32f7cc480418b2fd0ec22c4acbb9ce5
https://doi.org/10.1364/cleo_qels.2022.ftu4b.6
https://doi.org/10.1364/cleo_qels.2022.ftu4b.6
Autor:
Michael Woerner, Shekhar Priyadarshi, Isabel Gonzalez-Vallejo, Christoph Hauf, Klaus Reimann, Thomas Elsaesser
Publikováno v:
The International Conference on Ultrafast Phenomena (UP) 2022.
Femtosecond x-ray powder diffraction reveals the impact of zone-edge TA-phonon excitations on the valence-charge distribution in cubic BN. Transient charge-density maps show a spatial transfer of valence charge from the interstitial region onto boron
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_________::6c1c4dc29ef65fc40569fb87a2ad1179
https://doi.org/10.1364/up.2022.th2b.4
https://doi.org/10.1364/up.2022.th2b.4
Autor:
Debdeep Jena, Ryan Page, Bernard Gil, Giorgia Fugallo, Michael Woerner, Jia Zhang, Christos Flytzanis, Thomas Elsaesser, Taehee Kang, Klaus Reimann, Achintya Kundu, Michele Lazzeri, Guillaume Cassabois
Publikováno v:
Physical Review B: Condensed Matter (1978-1997)
Physical Review B: Condensed Matter (1978-1997), American Physical Society, 2021, 104 (14), pp.L140302. ⟨10.1103/PhysRevB.104.L140302⟩
Physical Review B
Physical Review B, 2021, 104 (14), pp.L140302. ⟨10.1103/PhysRevB.104.L140302⟩
Physical Review B: Condensed Matter (1978-1997), American Physical Society, 2021, 104 (14), pp.L140302. ⟨10.1103/PhysRevB.104.L140302⟩
Physical Review B
Physical Review B, 2021, 104 (14), pp.L140302. ⟨10.1103/PhysRevB.104.L140302⟩
International audience; Nonequilibrium dynamics of TO phonons and low-frequency interlayer shear modes are mapped in femtosecond mid-infrared pump-probe experiments. Time-resolved changes of TO phonon absorption reveal a TO phonon lifetime of 1.2 ps,
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::831c6d723d10f45e17c11432860260b8
https://doi.org/10.1103/physrevb.104.l140302
https://doi.org/10.1103/physrevb.104.l140302
Phonon-Induced Relocation of Valence Charge in Boron Nitride Observed by Ultrafast X-Ray Diffraction
Autor:
Shekhar Priyadarshi, Isabel Gonzalez-Vallejo, Christoph Hauf, Klaus Reimann, Michael Woerner, Thomas Elsaesser
Publikováno v:
Physical review letters. 128(13)
The impact of coherent phonon excitations on the valence charge distribution in cubic boron nitride is mapped by femtosecond x-ray powder diffraction. Zone-edge transverse acoustic (TA) two-phonon excitations generated by an impulsive Raman process i
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::23d3c254d77c8dc6c85d2028421b6944
https://pubmed.ncbi.nlm.nih.gov/35426722
https://pubmed.ncbi.nlm.nih.gov/35426722
Terahertz (THz) radiation with frequencies between 100 GHz and 30 THz has numerous applications in basic science, materials characterization, imaging, sensor technologies, and telecommunications. Recent progress in THz generation has provided ultrash
