Article
Polymer Science
Martyna Durko-Maciag, Gilles Ulrich, Julien Massue, Jaroslaw Mysliwiec, Konrad Cyprych
Summary: This work demonstrates the successful application of Excited-State Intramolecular Proton Transfer (ESIPT) fluorophores as photoinitiators for microfabrication. The influence of chemical structure on this application was investigated, followed by analysis of two-photon polymerization. The study determined the quality of fabricated structures and polymerization thresholds, with one of the chromophores having an impressively low value of 11 nJ.
EUROPEAN POLYMER JOURNAL
(2023)
Article
Chemistry, Physical
Amanuel M. Berhane, Christopher G. Baldwin, Keri Liang, Mojtaba Moshkani, Christopher Lustri, James E. Downes, Catherine Stampfl, Richard P. Mildren
Summary: The technique of two-photon etching on diamond surfaces allows controlled removal of atomic layers and nano-patterning, but the mechanism and pattern development are not fully understood. Research has shown that polarization and laser pulse duration have significant impacts on the surface patterns formed, leading to rules for predicting pattern type, roughness, and etch rate.
Article
Physics, Particles & Fields
Wei-Liang Qian, Kai Lin, Xiao-Mei Kuang, Bin Wang, Rui-Hong Yue
Summary: In this work, the authors study the black hole light echoes and their connection with the quasinormal modes. They find that the time-domain correlator naturally acquires the echo feature through the analysis of quasinormal modes and characteristic parameters of null geodesics. The dominant contributions to the light echoes come from those in the eikonal limit. Numerical demonstrations are provided for Schwarzschild black holes, and a potential difference between results obtained using geometric-optics approach and black hole perturbation theory is pointed out for Kerr spacetimes. The study has important implications for astrophysics.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Chemistry, Physical
Teng- Yang, Yu-Wen Huang, Prabesh Bista, Chien-Fang Ding, Jeson Chen, Cheng-Tien Chiang, Huan-Cheng Chang
Summary: The study reveals that fluorescent nanodiamonds emit red fluorescence when exposed to specific wavelength lasers. At low power, the emission is mainly due to excitation of electrons from the valence band of diamond to the NV0 centers, while at high power, nonresonant two-photon interband excitation dominates.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Brandon J. Furey, Benjamin J. Stacy, Tushti Shah, Rodrigo M. Barba-Barba, Ramon Carriles, Alan Bernal, Bernardo S. Mendoza, Brian A. Korgel, Michael C. Downer
Summary: Colloidal nanocrystalline silicon quantum dots (nc-SiQDs) excited by two-photon in the near-infrared (NIR) range have potential applications in deep biological imaging. The two-photon absorption (2PA) cross section of colloidal nc-SiQDs is measured, and it is found to be smaller for smaller diameter nanocrystals. The efficiencies of nc-SiQDs for bioimaging using two-photon excited photoluminescence (2PE-PL) are compared to other quantum dots and molecular fluorophores and found to be comparable or superior at greater depths.
Article
Engineering, Electrical & Electronic
Junwen Tang, Shenheng Xu, Fan Yang, Maokun Li
Summary: A reconfigurable transmitarray antenna with continuous 360-degree transmission phase control capability has been designed and experimentally validated. The element uses a unique structure to provide a wide bandwidth and high gain, with good beam steering capability within +/- 60 degrees.
IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Alexei Novikov, Stephen White
Summary: In this work, we introduce MISTR (Multidimensional Intersection Sparse supporT Recovery), an algorithm that utilizes the structure of multi-dimensional signals to recover the support from magnitude-only measurements with the same accuracy as the best one-dimensional algorithms. Theoretical analysis shows that MISTR can correctly recover the support of signals distributed as a Gaussian point process with high probability under certain sparsity constraints, and provides a thresholding scheme for handling noisy measurements. The algorithm's effectiveness is further demonstrated through detailed numerical experiments, showing near-linear time complexity in practice.
IEEE TRANSACTIONS ON SIGNAL PROCESSING
(2021)
Article
Chemistry, Physical
Xinyue Wang, Di Wang, Jia Li, Meixia Zhang, Peng Song
Summary: The theoretical study investigated the photoinduced charge transfer process of D-D-pi-A molecules, showing red shift in absorption spectrum and increased absorption intensity due to donor insertion. Visualization method was used to observe charge transfer in one- and two-photon absorption processes, with the thiazolo[5,4-d]thiazole donor insertion showing the largest TPA cross-section. This work contributes to understanding D-D-pi-A molecules and designing molecules with large cross-section TPA properties.
Article
Optics
Saumya Biswas, S. J. van Enk
Summary: This article introduces a model for describing a type of two-photon detector consisting of one molecule that can detect two photons arriving sequentially in time. The detector model includes a Hamiltonian description for amplifying the microscopic change and converting it into a macroscopic signal.
Article
Engineering, Electrical & Electronic
Yu Xiao, Bin Xi, Meng Xiang, Fan Yang, Zengping Chen
Summary: This study introduces a 1-bit wideband reconfigurable unit cell for transmitarray applications in Ku-band, which is fabricated and tested using a specific waveguide simulator. Experimental results show that the unit cell has low insertion losses and high phase stability.
IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS
(2021)
Article
Chemistry, Multidisciplinary
N. Maximilian Bojanowski, Aleksandra Vranic, Vincent Hahn, Pascal Rietz, Tobias Messer, Julian Brueckel, Christopher Barner-Kowollik, Eva Blasco, Stefan Braese, Martin Wegener
Summary: Recent studies have introduced a new generation of photoinitiators for 3D laser nanoprinting, replacing two-photon absorption with two-step absorption. This can now be achieved using inexpensive blue laser diodes instead of expensive femtosecond laser systems. Additionally, researchers are exploring alternative photoinitiators that can be excited by one-color two-step absorption and be de-excited by a different laser color.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Computer Science, Information Systems
Zonghuan Wu, Junming Zhao, Ke Chen, Yijun Feng
Summary: This paper proposes an active metamaterial absorber loaded with PIN diodes, which achieves broadband absorption at different frequencies by adjusting the bias currents of the diodes. The absorber has excellent performance and tunable absorption frequencies.
Article
Chemistry, Physical
Hailong Yu, Jia Liu, Jun Wang, Jing Liu, Hanqi Xu, Jinyang Yu, Wenzhi Wu
Summary: Lead-based halide perovskite has been extensively studied as a material for solar cells and LEDs. However, improving its optoelectronic characteristics and understanding its photophysical mechanism with laser interaction remains challenging. This study investigates the nonlinear optical absorption and two-photon luminescent properties of FAPbBr3 nanocrystals using various techniques. The results show different effects of 400 nm and 800 nm femtosecond laser excitation on the PL peak position and linewidth, indicating potential applications in multifunctional photonic sources and nanolaser devices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Review
Chemistry, Multidisciplinary
Pavel B. Sorokin, Boris Yakobson
Summary: Two-dimensional diamond, or diamane, is an ultrathin film that combines the physical properties of bulk crystal with nanoscale features. Research is currently focused on theoretical studies and synthesis challenges due to surface effects. Despite the challenges, there are promising prospects for the field of diamane research.
Article
Chemistry, Inorganic & Nuclear
Sandeep Kumar, Jitendra Nath Acharyya, Dipanjan Banerjee, Venugopal Rao Soma, G. Vijaya Prakash, Muniappan Sankar
Summary: A series of new push-pull meso-substituted trans-A(2)BC porphyrins have been synthesized and characterized using various techniques, showing excellent nonlinear optical properties suitable for optical switching applications, particularly due to the polarized push-pull effect of the nitrophenyl-substituted porphyrins.
DALTON TRANSACTIONS
(2021)
Article
Materials Science, Multidisciplinary
Amala Elizabeth, Sudhir K. Sahoo, David Lockhorn, Alexander Timmer, Nabi Aghdassi, Helmut Zacharias, Thomas D. Kuehne, Susanne Siebentritt, Hossein Mirhosseini, Harry Moenig
PHYSICAL REVIEW MATERIALS
(2020)
Article
Chemistry, Medicinal
Paul Valerian Moellers, Selma Ulku, Dilhara Jayarathna, Francesco Tassinari, Daniel Nuerenberg, Ron Naaman, Catalina Achim, Helmut Zacharias
Summary: Monolayers of chiral molecules can act as efficient spin filters, with double-stranded peptide nucleic acid SAMs playing a crucial role in spin selectivity. The introduction of chiral centers may enhance the spin filtering capacity.
Article
Instruments & Instrumentation
V Kaercher, S. Roling, L. Samoylova, A. Buzmakov, U. Zastrau, K. Appel, M. Yurkov, E. Schneidmiller, F. Siewert, H. Zacharias
Summary: The split-and-delay unit (SDU) for the High-Energy-Density (HED) beamline at the SASE2 undulator of the European XFEL enables time-resolved pump/probe experiments with photon energies between 5 keV and 24 keV. Optical layout and simulations were used to study the impact on spatio-temporal properties of the XFEL pulses. The simulations showed that the topographies of the SDU mirrors are sufficient to support X-ray pump/X-ray probe experiments.
JOURNAL OF SYNCHROTRON RADIATION
(2021)
Article
Chemistry, Physical
Tobias Reiker, Zitong Liu, Carsten Winter, Nils Fabian Kleimeier, Deqing Zhang, Helmut Zacharias
Summary: Conjugated polymers based on DPP, combined with different donors, were studied for electronically excited state lifetimes and charge transport properties using time-resolved spectroscopy. After annealing, the ultrafast decay of electrons extended, possibly connected with improved charge transport in the film.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Multidisciplinary Sciences
Thomas Ding, Marc Rebholz, Lennart Aufleger, Maximilian Hartmann, Veit Stooss, Alexander Magunia, Paul Birk, Gergana Dimitrova Borisova, David Wachs, Carina da Costa Castanheira, Patrick Rupprecht, Yonghao Mi, Andrew R. Attar, Thomas Gaumnitz, Zhi-Heng Loh, Sebastian Roling, Marco Butz, Helmut Zacharias, Stefan Duesterer, Rolf Treusch, Arvid Eislage, Stefano M. Cavaletto, Christian Ott, Thomas Pfeifer
Summary: High-intensity ultrashort pulses at extreme ultraviolet (XUV) and x-ray photon energies delivered by state-of-the-art free-electron lasers (FELs) are transforming the field of ultrafast spectroscopy. A technique based on fundamental nonlinear optics has been experimentally demonstrated for the direct measurement of the frequency chirp of extreme-ultraviolet free-electron laser pulses, providing in-situ information on the time-energy structure of the pulses. By utilizing a rate-equation model, the frequency chirp can be directly extracted and quantified from measured data, without relying on an additional external field.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
Marc Rebholz, Thomas Ding, Victor Despre, Lennart Aufleger, Maximilian Hartmann, Kristina Meyer, Veit Stooss, Alexander Magunia, David Wachs, Paul Birk, Yonghao Mi, Gergana Dimitrova Borisova, Carina da Costa Castanheira, Patrick Rupprecht, Georg Schmid, Kirsten Schnorr, Claus Dieter Schroeter, Robert Moshammer, Zhi-Heng Loh, Andrew R. Attar, Stephen R. Leone, Thomas Gaumnitz, Hans Jakob Woerner, Sebastian Roling, Marco Butz, Helmut Zacharias, Stefan Duesterer, Rolf Treusch, Gunter Brenner, Jonas Vester, Alexander Kuleff, Christian Ott, Thomas Pfeifer
Summary: In this study, an extreme-ultraviolet free-electron laser is used to excite a gas-phase di-iodomethane target, allowing for the investigation of molecular dissociation pathways and geometries in a time-resolved manner. The method presented in this work provides a sensitive approach to study excited-state molecular structures and reactions triggered by core-resonance at specific sites.
Article
Chemistry, Physical
Marc Rebholz, Thomas Ding, Lennart Aufleger, Maximilian Hartmann, Kristina Meyer, Veit Stooss, Alexander Magunia, David Wachs, Paul Birk, Yonghao Mi, Gergana Dimitrova Borisova, Carina da Costa Castanheira, Patrick Rupprecht, Maia Magrakvelidze, Uwe Thumm, Sebastian Roling, Marco Butz, Helmut Zacharias, Stefan Duesterer, Rolf Treusch, Guenter Brenner, Christian Ott, Thomas Pfeifer
Summary: In this experiment, a time-resolved spectroscopy study was conducted on the dissociation of oxygen molecules using intense XUV light. Two different dissociation pathways and corresponding time scales were observed, providing insights into the dynamics of molecular dissociation. Future experiments are expected to offer a detailed view of the coupled nuclear and electronic dynamics during this process by tuning pulse frequencies and increasing probe-pulse bandwidth.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Review
Chemistry, Multidisciplinary
Clarice D. Aiello, John M. Abendroth, Muneer Abbas, Andrei Afanasev, Shivang Agarwal, Amartya S. Banerjee, David N. Beratan, Jason N. Belling, Bertrand Berche, Antia Botana, Justin R. Caram, Giuseppe Luca Celardo, Gianaurelio Cuniberti, Aitzol Garcia-Etxarri, Arezoo Dianat, Ismael Diez-Perez, Yuqi Guo, Rafael Gutierrez, Carmen Herrmann, Joshua Hihath, Suneet Kale, Philip Kurian, Ying-Cheng Lai, Tianhan Liu, Alexander Lopez, Ernesto Medina, Vladimiro Mujica, Ron Naaman, Mohammadreza Noormandipour, Julio L. Palma, Yossi Paltiel, William Petuskey, Joao Carlos Ribeiro-Silva, Juan Jose Saenz, Elton J. G. Santos, Maria Solyanik-Gorgone, Volker J. Sorger, Dominik M. Stemer, Jesus M. Ugalde, Ana Valdes-Curiel, Solmar Varela, David H. Waldeck, Michael R. Wasielewski, Paul S. Weiss, Helmut Zacharias, Qing Hua Wang
Summary: This review focuses on the study of chiral degrees of freedom in matter and electromagnetic fields, discussing the recent observations of the chiral-induced spin selectivity effect and the nanophotonic strategies designed to amplify chiral light-matter interactions. The CISS effect offers opportunities for spin control and the design of room-temperature quantum devices, while chiral-optical effects could have advantages in all-optical and quantum information technologies. The review presents a vision for the future roles of chiral-influenced quantum effects in enabling room-temperature quantum technologies.
Article
Chemistry, Multidisciplinary
Paul Moellers, Jimeng Wei, Soma Salamon, Manfred Bartsch, Heiko Wende, David H. Waldeck, Helmut Zacharias
Summary: The chirality-induced spin selectivity (CISS) effect allows for controlling spin-dependent chemical reactions, such as photoinduced water splitting. This effect has been observed in organic chiral molecules, but its emergence in chiral inorganic materials is still not well-understood. In this study, chiral CuO films were deposited on partially UV-transparent gold substrates and subjected to deep-UV laser pulses. The spin polarization of photoelectrons was measured and found to be energy dependent, suggesting a contribution from the CISS effect in addition to intrinsic spin polarization in the CuO film.
Review
Chemistry, Multidisciplinary
Paul Moellers, Benjamin Goehler, Helmut Zacharias
Summary: In this article, we discuss the manifestation of the chirality-induced spin selectivity (CISS) effect in photoelectron spectroscopy experiments. We evaluate various systems and observe high spin polarization values, with the longitudinal spin orientation changing sign with a change of the enantiomeric form. Recent advances allow for distinguishing the contributions of electrons with different kinetic energies to the electron spin polarization, and thus distinguish the CISS effect from bulk contributions to the spin originating from different mechanisms.
ISRAEL JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Physical
Deb Kumar Bhowmick, Adrian Joe Urban, Manfred Bartsch, Bjoern Braunschweig, Helmut Zacharias
Summary: Efficient control of interface chemistry enables better tunability of electronic properties, and a novel near-UV-initiated direct modification method has been demonstrated to form stable organic monolayers on silicon surfaces with high hydrolytic stability.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Optics
Evgeny Schneidmiller, Matthias Dreimann, Marion Kuhlmann, Juliane Roensch-Schulenburg, Helmut Zacharias
Summary: A recently proposed concept allows for obtaining much shorter pulses in Self-Amplified Spontaneous Emission Free Electron Lasers (SASE FELs) by suppressing radiation in the long main undulator while preserving microbunching within a shorter lasing slice. The method of excessive reverse undulator taper is discussed and illustrated numerically in this paper, with first experimental tests performed at the soft X-ray FEL user facility FLASH. The measured pulse duration approaches 1 fs (FWHM) at the wavelength of 5 nm.
Article
Chemistry, Physical
Daniel Nuerenberg, Andrew G. G. Mark, Peer Fischer, Helmut Zacharias
Summary: We investigate the electron emission from 3D chiral silver alloy nanohelices initiated by femtosecond laser pulses. We find hot but thermally distributed electron spectra and a strong anisotropy in the electron yield with left- and right-circularly polarized light excitations, which invert in sign between left- and right-handed helices. Measurements of the reflectance and simulations of the absorbance of the helices based on retarded field calculations are compared to the anisotropy in photoemission.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Marek K. Charyton, Tobias Reiker, Kamil Kotwica, Monika Gora, Helmut Zacharias, Nicolas D. Boscher
Summary: Conjugated polymers based on diketopyrrolopyrrole (DPP) are important high-performance organic semiconductors. N-alkylation is necessary for the solution synthesis of DPP-based CPs, while oxidative chemical vapour deposition (oCVD) provides a solventless and scalable approach for the polymerisation of N-unsubstituted DPP. The oCVD reaction of TDPP yields polymer thin films with H-bonding and conjugated covalent bonds, resulting in higher conductivity and increased lifetime of electronically excited states compared to N-alkylated counterparts.
MATERIALS ADVANCES
(2023)
Article
Chemistry, Physical
Thomas Ding, Marc Rebholz, Lennart Aufleger, Maximilian Hartmann, Veit Stooss, Alexander Magunia, Paul Birk, Gergana Dimitrova Borisova, Carina da Costa Castanheira, Patrick Rupprecht, Yonghao Mi, Thomas Gaumnitz, Zhi-Heng Loh, Sebastian Roling, Marco Butz, Helmut Zacharias, Stefan Duesterer, Rolf Treusch, Christian Ott, Thomas Pfeifer
Summary: The emergence of ultra-intense extreme-ultraviolet (XUV) and X-ray free-electron lasers (FELs) has enabled the experimental realization of non-linear XUV and X-ray spectroscopy techniques. This study demonstrates an experimental setup for all-XUV transient absorption spectroscopy on gas-phase targets at the FEL, providing insights into the dynamics of light-matter interactions in the XUV and X-ray spectral range.
FARADAY DISCUSSIONS
(2021)
