Articles de revues : « Laser-Molecules interaction »

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Oreshkin, A. I., D. A. Muzychenko, S. I. Oreshkin, V. I. Panov, V. O. Surov, N. S. Maslova et M. N. Petukhov. « Quantum traps for coupling of fluorofullerene molecules ». Laser Physics Letters 20, n^o 1 (1 décembre 2022) : 015202. http://dx.doi.org/10.1088/1612-202x/aca4ce.

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Abstract The interaction of fluorine atoms with Cu(111) surface has been analyzed by means of scanning tunneling microscopy and x-ray photoelectron spectroscopy (XPS). A submonolayer coverage of fluorinated fullerene C60F18 has been chosen to provide a well controllable arrival of fluorine atoms on copper surface. The appearance of F-induced surface structures on the Cu(111) surface caused by defluorination of C60F18 molecules adsorbed on the surface was shown. XPS measurements unambiguously indicate the existence of chemical state of fluorine not typical for CuF2 formation. Superstructure of well ordered metastable clusters consisting of fluorofullerene molecules are formed on the Cu(111) surface as a result of the balance of two interactions: the dipole-dipole interaction between fluorofullerene molecules and the interaction of C60F18 molecules with the two-dimensional gas phase, emerging above the copper surface. Regular surface structure formed by fullerene molecules interacting through collective vibrational mode can be used for entanglement formation between two qubits each associated with ground and excited electronic states of the molecule by applying two coherent laser pulses.

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Bauer, Dieter. « Molecules and Clusters in Intense Laser Fields ». Laser and Particle Beams 20, n^o 3 (juillet 2002) : 541–42. http://dx.doi.org/10.1017/s0263034602002318.

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The interaction of intense laser light with molecules and clusters is a rapidly evolving research area. Its attraction lies in both the underlying fundamental physics and the prospects for applications. The interaction of intense laser light with rare-gas clusters, for instance, leads to megaelectron volt electrons, multikiloelectron volt ions, and bright X-ray emission. In laser-irradiated D2 clusters, thermonuclear fusion has been achieved.

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Yang, Jinghui, Cuiying Huang et Xinping Zhang. « Femtosecond Optical Annealing Induced Polymer Melting and Formation of Solid Droplets ». Polymers 11, n^o 1 (13 janvier 2019) : 128. http://dx.doi.org/10.3390/polym11010128.

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Interaction between femtosecond laser pulses with polymeric thin films induced transient optical annealing of the polymer molecules. Melting of the polymer films took place during the transient annealing process, so that a solid-liquid-solid phase transition process was observed. Ultrafast cooling of the melting polymer produced solidified droplets. Microscopic and spectroscopic characterization revealed that the polymer molecules were rearranged with preferable H-aggregation to reach the lowest formation energy during the melting process. Intermolecular coupling was enhanced due to the modified molecular arrangement. This observation of melting of polymeric semiconductors due to the interaction with femtosecond light pulses is potentially important for better understanding laser-matter interactions and for exploring organic optoelectronic devices through special material processing.

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Ponomarev, Yu N., et S. R. Uogintas. « Nonresonant interaction of femtosecond laser pulse with centrosymmetric molecules ». Optics Communications 283, n^o 4 (février 2010) : 591–94. http://dx.doi.org/10.1016/j.optcom.2009.10.090.

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Zhang, Bin, et Zengxiu Zhao. « SLIMP : Strong laser interaction model package for atoms and molecules ». Computer Physics Communications 192 (juillet 2015) : 330–41. http://dx.doi.org/10.1016/j.cpc.2015.02.031.

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De Moor, Roeland Jozef Gentil, Jeroen Verheyen, Peter Verheyen, Andrii Diachuk, Maarten August Meire, Peter Jozef De Coster, Mieke De Bruyne et Filip Keulemans. « Laser Teeth Bleaching : Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo ». Scientific World Journal 2015 (2015) : 1–12. http://dx.doi.org/10.1155/2015/835405.

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Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength.

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E. Prieto, L. X. Hallado, A. Guerrero, I. Álvarez et C. Cisneros. « Effect of Laser Radiation on Biomolecules ». Journal of Nuclear Physics, Material Sciences, Radiation and Applications 7, n^o 2 (28 février 2020) : 123–28. http://dx.doi.org/10.15415/jnp.2020.72015.

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Time of flight laser photoionization has been used to study the response of some molecules of biological interest under laser radiation. One of the questions of great interest today is the effect of radiation on DNA and RNA molecules. Damage to these molecules can be caused directly by radiation or indirectly by secondary electrons created by radiation. As response of the radiation field fragmentation process can occur producing different ions with kinetic energies of a few electron volts. In this paper we present the results of the interaction of 355nm laser with the nitrogen bases adenine(A) and uracil(U) using time-of-flight spectrometry and the comparison of experimental results on the effects of laser radiation in (A) and (U) belonging to two different ring groups, purines and pyrimidines respectively,which are linked to form the AU pair of the RNA.

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Shirakawa, Masayuki, Takayoshi Kobayashi et Eiji Tokunaga. « Solvent Effects in Highly Efficient Light-Induced Molecular Aggregation ». Applied Sciences 9, n^o 24 (9 décembre 2019) : 5381. http://dx.doi.org/10.3390/app9245381.

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It has been reported that when irradiated with laser light non-resonant with the main absorption peaks, porphyrin molecules (4-[10,15,20-tris(4-sulfophenyl)-21,24-dihydroporphyrin-5-yl]benzenesulfonic acid, TPPS) in an aqueous solution become 10,000 to 100,000 times more efficient in light-induced molecular aggregation than expected from the ratio of gradient force potential to the thermal energy of molecules at room temperature. To determine the mechanism of this phenomenon, experiments on the light-induced aggregation of TPPS in alcohol solutions (methanol, ethanol, and butanol) were performed. In these alcohol solutions, the absorbance change was orders of magnitude smaller than in the aqueous solution. Furthermore, it was found that the absorbance change in the aqueous solution tended to be saturated with the increase of the irradiation intensity, but in the ethanol solution, the absorbance change increased linearly. These results can be qualitatively explained by the model in which intermolecular light-induced interactions between molecules within a close distance among randomly distributed molecules in the laser irradiation volume are highly relevant to the signal intensity. However, conventional dipole–dipole interactions, such as the Keesom interaction, are not quantitatively consistent with the results.

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Muraviev, Dmitri, Natalya V. Drozdova, Nina B. Dolgina et Aleksandr A. Karabutov. « Potentiometric and Laser-Acoustic Study of Aminecarboxylate Interaction of Amino Acid Molecules ». Langmuir 14, n^o 7 (mars 1998) : 1822–28. http://dx.doi.org/10.1021/la971145v.

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Bedurke, Florian, Tillmann Klamroth et Peter Saalfrank. « Many-electron dynamics in laser-driven molecules : wavefunction theory vs. density functional theory ». Physical Chemistry Chemical Physics 23, n^o 24 (2021) : 13544–60. http://dx.doi.org/10.1039/d1cp01100f.

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Molecules excited by laser pulses give rise to High Harmonic Generation and other responses. These are computed here with time-dependent configuration interaction and density functional theories, two popular many-electron methods.

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Kautz, E. J., P. J. Skrodzki, M. Burger, B. E. Bernacki, I. Jovanovic, M. C. Phillips et S. S. Harilal. « Time-resolved imaging of atoms and molecules in laser-produced uranium plasmas ». Journal of Analytical Atomic Spectrometry 34, n^o 11 (2019) : 2236–43. http://dx.doi.org/10.1039/c9ja00228f.

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Ponomarev, Yu N. « Photo-acoustic investigation of the interaction of laser radiation with molecules and inter-molecular interactions in gases ». Infrared Physics 32 (janvier 1991) : 377–84. http://dx.doi.org/10.1016/0020-0891(91)90126-z.

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Sanny, A. I., W. M. Edmund Loh, C. J. Wong et Naser M. Ahmed. « Experimental investigation of unique color-changing property of multicolored sparkling of microbubbles formed due to femtosecond laser–water interaction ». Modern Physics Letters B 33, n^o 18 (26 juin 2019) : 1950208. http://dx.doi.org/10.1142/s0217984919502087.

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We present an experimental study on the interaction between femtosecond laser and water. When a beam of femtosecond laser is focused at a single point inside water, nonlinear interaction between the laser and water molecules gives rise to several interesting optical phenomena, starting with filamentation, supercontinuum white light generation and then the formation of cavitation microbubbles near the laser focus region. We observe drifting of the laser focus region and cavitation bubbles against the direction of laser propagation with increasing laser power. Due to conical emission, geometric scattering of white light on the bubble surface manifests itself as multicolored sparkling at the edge of the bubbles. Careful analysis of the video footage of the geometric scattering event reveals a unique color-changing property which occurs only within a tiny fraction of a second. This property can be explained as due to the hydrodynamical flow of the laser-induced plasma strings that leads to instability in the frequency of the emitted light.

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Qi, Pengfei, Wenqi Qian, Lanjun Guo, Jiayun Xue, Nan Zhang, Yuezheng Wang, Zhi Zhang et al. « Sensing with Femtosecond Laser Filamentation ». Sensors 22, n^o 18 (19 septembre 2022) : 7076. http://dx.doi.org/10.3390/s22187076.

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Femtosecond laser filamentation is a unique nonlinear optical phenomenon when high-power ultrafast laser propagation in all transparent optical media. During filamentation in the atmosphere, the ultrastrong field of 1013–1014 W/cm2 with a large distance ranging from meter to kilometers can effectively ionize, break, and excite the molecules and fragments, resulting in characteristic fingerprint emissions, which provide a great opportunity for investigating strong-field molecules interaction in complicated environments, especially remote sensing. Additionally, the ultrastrong intensity inside the filament can damage almost all the detectors and ignite various intricate higher order nonlinear optical effects. These extreme physical conditions and complicated phenomena make the sensing and controlling of filamentation challenging. This paper mainly focuses on recent research advances in sensing with femtosecond laser filamentation, including fundamental physics, sensing and manipulating methods, typical filament-based sensing techniques and application scenarios, opportunities, and challenges toward the filament-based remote sensing under different complicated conditions.

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YAO, DUANZHENG, et GUIGUANG XIONG. « THEORETICAL STUDIES ON NONLINEAR INTERACTION BETWEEN LASER AND BIO-MOLECULES IN OPTICAL TOMOGRAPHY ». Modern Physics Letters B 18, n^o 15 (20 juin 2004) : 749–55. http://dx.doi.org/10.1142/s0217984904007232.

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The nonlinear interaction between laser and bio-molecule has been studied by the theory of molecular nonlinear polarization. The expressions of operators of Hamiltonian, the moment of dipole and the electric susceptibility with different orders have been evaluated. The contributions of electrons and nuclei to the molecular polarization have been analyzed. A SHG tomography induced by third-order nonlinear optical effect has also been proposed.

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SCHMIDT, M., P. D'OLIVEIRA, P. MEYNADIER, D. NORMAND et C. CORNAGGIA. « STRONG LASER FIELD INTERACTION WITH DIATOMIC MOLECULES : FROM THE ULTRA-SHORT TO LONG-PULSE REGIME ». Journal of Nonlinear Optical Physics & ; Materials 04, n^o 04 (octobre 1995) : 817–29. http://dx.doi.org/10.1142/s0218863595000367.

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In the present paper, we compare novel MEDI results on iodine obtained with 30 ps laser pulses to those obtained in the femtosecond regime. The results indicate laser-induced trapping of the molecules not only in the ultra-short pulse regime, but also for the long pulses, since the fragment kinetic energy releases are essentially the same, although the pulse duration is varied over more than two orders of magnitude. Most interestingly, with 30 ps pulses significant post-dissociation ionization of the In+-fragments observed for the first time, proving that near-Coulomb energies and post-dissociation ionization can be observed simultaneously. A femtosecond double-pulse experiment confirms our recent hypothesis of molecular stabilization governing the MEDI interaction.

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GRAHAM, P., X. FANG, K. W. D. LEDINGHAM, R. P. SINGHAL, T. McCANNY, D. J. SMITH, C. KOSMIDIS, P. TZALLAS, A. J. LANGLEY et P. F. TADAY. « Unusual fragmentation patterns from the dissociation of some small molecules ». Laser and Particle Beams 18, n^o 3 (juillet 2000) : 417–32. http://dx.doi.org/10.1017/s0263034600183107.

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The nonlinear interaction of molecular matter with the intense field of a linearly-polarized laser beam, allows the study of not only the ionization dynamics of the parent molecule, but also the angular distribution of the exploding fragments. This is carried out by rotating the polarization vector of the laser with respect to the laboratory reference frame. The angular distributions for the CS2, CO2, N2O, H2S, and CH3I molecular ions, at intensities of about 1016 W cm−2, are presented. The distributions seem to be dependent on the molecule under consideration, but common features are that the peripheral atoms of the molecule are ejected along the ToF-axis, and the central atom perpendicularly to it, whenever the polarization vector and ToF-axis are collinear. It would seem that the distributions for the lighter of the molecules are partly due to alignment via dipole moments induced by the laser, as the distributions narrow as their charge-state increases. This is indicative of a larger torque acting on the higher-charged precursor molecular ion, via the interaction of the field with the laser-induced dipole moment. On the other hand, the angular dependence of the heavier molecules studied, are thought to originate from a dependence of the ionization/dissociation probability of the molecular ion on the initial angle made between the molecular axis and the polarization vector, that is, a preferential ionization/dissociation process. Spatial alignment in the laser pulse, in this case, is not thought to occur since the peaks do not narrow as the ionic charge increases. Finally, the results for H2S and also N2O are particularly interesting, since distributions for up to S7+ are presented, while the N-distributions show both a parallel and perpendicular component of the distribution. Neither of these results has, to the author's knowledge, been previously observed.

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Zamfir, V., K. Tanaka et C. Ur. « Extreme light infrastructure nuclear physics (ELI-NP) ». Europhysics News 50, n^o 2 (mars 2019) : 23–25. http://dx.doi.org/10.1051/epn/2019204.

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ELI - Extreme Light Infrastructure, a project to build an international research infrastructure “dedicated to the investigation and applications of laser matter interaction at the highest intensity level” is one of the 35 projects in the first Roadmap, in 2006, of the European Strategy Forum on Research Infrastructures (ESFRI) [1]. “ELI will comprise three branches: ultra high field science that will explore laser matter interaction up to the nonlinear QED limit including the investigation of pair creation and vacuum structure; attosecond laser science designed to conduct temporal investigation at the attosecond scale of electron dynamics in atoms, molecules, plasmas, and solids; lastly, the highenergy beam facility devoted to the development of dedicated beam lines of ultra short pulses of high energy radiation and particles up to 100GeV for users.”

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Rosanov, Nikolay N., Sergey V. Fedorov, Leonid A. Nesterov et Nikolay A. Veretenov. « Extreme and Topological Dissipative Solitons with Structured Matter and Structured Light ». Nanomaterials 9, n^o 6 (31 mai 2019) : 826. http://dx.doi.org/10.3390/nano9060826.

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Structuring of matter with nanoobjects allows one to generate soliton-like light bundles with extreme characteristics—temporal duration and spatial dimensions. On the other hand, structuring of light gives the possibility to form light bundles with complicated internal structure; their topology could be used for information coding similar to that in self-replicating RNA molecules carrying genetic code. Here we review the both variants of structuring. In the first variant, we consider a linear molecular chain and organic film interacting resonantly with laser radiation. Demonstrated are optical bistability, switching waves, and dissipative solitons, whose sizes for molecular J-aggregates can reach the nanometer range. We also discuss some theoretical approaches to take into account multi-particle interaction and correlations between molecules. In the second variant, light structuring in large-size laser medium with saturable amplification and absorption is achieved by preparation of the initial field distribution with a number of closed and unclosed vortex lines where the field vanishes. Various types of topological solitons, parameter domains of their stability, and transformation of the solitons with slow variation of the scheme parameters are presented.

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BAUER, D., et F. CECCHERINI. « A numerical ab initio study of harmonic generation from a ring-shaped model molecule in laser fields ». Laser and Particle Beams 19, n^o 1 (janvier 2001) : 85–90. http://dx.doi.org/10.1017/s0263034601191135.

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When a laser pulse impinges on a molecule which is invariant under certain symmetry operations selection rules for harmonic generation (HG) arise. In other words, symmetry controls which channels are open for the deposition and emission of laser energy—with the possible application of filtering or amplification. We review the derivation of HG selection rules and study numerically the interaction of laser pulses with an effectively one-dimensional ring-shaped model molecule. The harmonic yields obtained from that model and their dependence on laser frequency and intensity are discussed. In a real experiment obvious candidates for such molecules are benzene, other aromatic compounds, or even nanotubes.

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Xu, Mei, Dong-Sheng Li, Bin Li, Chao Wang, Yu-Peng Zhu, Wen-Ping Lv et Bi-Jun Xie. « Comparative Study on Molecular Weight of Konjac Glucomannan by Gel Permeation Chromatography-Laser Light Scattering-Refractive Index and Laser Light-Scattering Methods ». Journal of Spectroscopy 2013 (2013) : 1–4. http://dx.doi.org/10.1155/2013/685698.

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The gel permeation chromatography, combined with laser light scattering and refractive index (GPC-LLS-RI) online method and laser light scattering (LLS) single method, researched the weight-average molecular weight (Mw) of konjac glucomannan (KGM) in this paper. The results show that the determination results of molecular weight of KGM are similar by two method, the molecular weight of KGM is2.476×105 g/mol by online method measured, and it is2.508×105 g/mol by single method measured, compared with only 1.3% difference between the two methods. At the same time, the molecular weight distributions of KGM and conformation index were analyzed by online method, while the second virial coefficient (A2) that characterizes the interaction between KGM molecules and solvent molecules was acquired by single method, which can provide reliable foundation for the molecular chain morphology research of KGM.

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Artemov, V. G., P. O. Kapralov, D. M. Kurmasheva, V. I. Tikhonov et A. A. Volkov. « A laser analyzer of the kinetics of interaction of water molecules with an adsorbent ». Instruments and Experimental Techniques 56, n^o 5 (septembre 2013) : 602–6. http://dx.doi.org/10.1134/s0020441213040143.

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Fernández-Menchero, L., T. Kirchner et P. E. Blöchl. « Theoretical study of interaction of laser with diatomic molecules using the Basis Generator Method ». Journal of Physics : Conference Series 194, n^o 3 (1 novembre 2009) : 032052. http://dx.doi.org/10.1088/1742-6596/194/3/032052.

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Park, Daniel J., Jessie C. Ku, Lin Sun, Clotilde M. Lethiec, Nathaniel P. Stern, George C. Schatz et Chad A. Mirkin. « Directional emission from dye-functionalized plasmonic DNA superlattice microcavities ». Proceedings of the National Academy of Sciences 114, n^o 3 (4 janvier 2017) : 457–61. http://dx.doi.org/10.1073/pnas.1619802114.

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Three-dimensional plasmonic superlattice microcavities, made from programmable atom equivalents comprising gold nanoparticles functionalized with DNA, are used as a testbed to study directional light emission. DNA-guided nanoparticle colloidal crystallization allows for the formation of micrometer-scale single-crystal body-centered cubic gold nanoparticle superlattices, with dye molecules coupled to the DNA strands that link the particles together, in the form of a rhombic dodecahedron. Encapsulation in silica allows one to create robust architectures with the plasmonically active particles and dye molecules fixed in space. At the micrometer scale, the anisotropic rhombic dodecahedron crystal habit couples with photonic modes to give directional light emission. At the nanoscale, the interaction between the dye dipoles and surface plasmons can be finely tuned by coupling the dye molecules to specific sites of the DNA particle-linker strands, thereby modulating dye–nanoparticle distance (three different positions are studied). The ability to control dye position with subnanometer precision allows one to systematically tune plasmon–excition interaction strength and decay lifetime, the results of which have been supported by electrodynamics calculations that span length scales from nanometers to micrometers. The unique ability to control surface plasmon/exciton interactions within such superlattice microcavities will catalyze studies involving quantum optics, plasmon laser physics, strong coupling, and nonlinear phenomena.

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Li, Jiajun, Yunyun Mu, Miao Liu et Xinping Zhang. « Direct Laser Writing of SERS Hollow Fibers ». Nanomaterials 12, n^o 16 (18 août 2022) : 2843. http://dx.doi.org/10.3390/nano12162843.

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We report the direct laser writing (DLW) of surface-enhanced Raman scattering (SERS) structures on the inner wall of a hollow fiber. Colloidal gold–silver alloy nanoparticles (Au–Ag ANPs) are firstly coated onto the inner wall of a hollow fiber. A green laser beam is focused through the outer surface of the hollow fiber to interact with colloidal Au–Ag ANPs so that they become melted and aggregated on the surface of the inner wall with strong adhesion. Such randomly distributed plasmonic nanostructures with high density and small gaps favor the SERS detection of low-concentration molecules in liquids flowing through the hollow fiber. Such a SERS device also supplies a three-dimensional microcavity for the interaction between excitation laser and the target molecules. The DLW system consists mainly of the flexible connection between the motor shaft and the hollow fiber, the program-controlled translation of the hollow fiber along its symmetric axis and rotation about the axis, as well as the mechanical design and the computer control system. This DLW technique enables high production, high stability, high reproducibility, high precision, and a high-flexibility fabrication of the hollow fiber SERS device. The resultant microcavity SERS scheme enables the high-sensitivity detection of R6G molecules in ethanol with a concentration of 10−7 mol/L.

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Brown, Alex, et William J. Meath. « On the effects of absolute laser phase on the interaction of a pulsed laser with polar versus nonpolar molecules ». Journal of Chemical Physics 109, n^o 21 (décembre 1998) : 9351–65. http://dx.doi.org/10.1063/1.477596.

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ZHANG, GUILAN, DONG XIAO, CHUNLIU ZHAO, GUOQING TANG et WENJU CHEN. « EFFECT OF SOLVENT ON NONLINEAR REFRACTION INDEX OF 7-HYDROXYQUINOLINE ». Journal of Nonlinear Optical Physics & ; Materials 10, n^o 03 (septembre 2001) : 305–9. http://dx.doi.org/10.1142/s0218863501000656.

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Nonlinear refraction index n2 of 7-hydroxyquinoline in different solvents was measured using Z-scan techniques with picosecond laser pulse. The effect of solvent on the nonlinear refraction index n2 of 7-hydroxyquinoline was investigated. The origination of this effect was due to the interaction between 7-hydroxyquinoline and the solvent molecules via H-bond.

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Filipiak, Piotr, Katarzyna Grzyb, Monika Borkowska et Tomasz Pedzinski. « Unveiling the Triplet-State Interaction Mechanism Between 4-Carboxybenzophenone and 2-Naphthalene Sulfonate—A Laser Flash Photolysis Study ». Photochem 5, n^o 1 (24 janvier 2025) : 4. https://doi.org/10.3390/photochem5010004.

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This communication aims to comprehensively elucidate the intricate mechanism governing the interaction between the excited triplet state of 4-Carboxybenzophenone (CB*) and the anionic form of 2-Naphthalene Sulfonate (NpSO3−), employing the 337 nm Nanosecond Laser Flash Photolysis technique for this investigation. When the CB is selectively excited by a 337 nm laser, two primary processes become possible: (i) energy transfer from 3CB* to NpSO3− and (ii) electron transfer from NpSO3− to 3CB*. The dynamics of these interactions are explored through experimental observations of transient absorption spectra and the analysis of respective kinetic traces. The primary process dominating in the 3(CB...NpSO3−)* system is identified as triplet energy transfer from excited 3CB* to 3(NpSO3−), as demonstrated by characteristic spectral features observed at 410–420 nm. Comparisons are made with a similar system studied by Yamaji and co-workers, 3(BP•−...NpO•)*, revealing differences in the priority of primary process occurrences. These findings contribute to a deeper understanding of the intricate interactions between excited molecules and ground-state donors, aiding in the comprehension of mechanisms governing these reactions.

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Truffert, Jean-Christophe, Ulysse Asseline, Nguyen T. Thuong et Andre Brack. « Synthesis, Characterization and Binding Properties of Peptide-Oligonucleotide Conjugates Containing the Spkk Peptide Motif ». Protein & ; Peptide Letters 2, n^o 3 (décembre 1995) : 419–24. http://dx.doi.org/10.2174/092986650203220601164632.

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Peptide-oligonucleotide hybrid molecules 6 and 7 have been synthesized by on-line solid phase synthesis using allyloxycarbonyl (Alloc) side chain protection for serine. The conjugates have been characterized by ma.trix-assisted laser desorption ionization time-of-flight mass spectrometry. The interaction of conjugates 6 and 7 with a complementary sequence has been studied by absorption spectroscopy.

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Truffert, Jean-Christophe, Ulysse Asseline, Nguyen T. Thuong et Andre Brack. « Synthesis, Characterization and Binding Properties of Peptide-Oligonucleotide Conjugates Containing the Spkk Peptide Motif ». Protein & ; Peptide Letters 2, n^o 3 (décembre 1995) : 419–24. http://dx.doi.org/10.2174/092986650203220601164632.

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Peptide-oligonucleotide hybrid molecules 6 and 7 have been synthesized by on-line solid phase synthesis using allyloxycarbonyl (Alloc) side chain protection for serine. The conjugates have been characterized by ma.trix-assisted laser desorption ionization time-of-flight mass spectrometry. The interaction of conjugates 6 and 7 with a complementary sequence has been studied by absorption spectroscopy.

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Wakabayashi, Tomonari, Urszula Szczepaniak, Kaito Tanaka, Satomi Saito, Keisuke Fukumoto, Riku Ohnishi, Kazunori Ozaki et al. « Phosphorescence of Hydrogen-Capped Linear Polyyne Molecules C8H2, C10H2 and C12H2 in Solid Hexane Matrices at 20 K ». Photochem 2, n^o 1 (28 février 2022) : 181–201. http://dx.doi.org/10.3390/photochem2010014.

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Laser-ablated polyyne molecules, H(C≡C)nH, were separated by size in solutions and co-condensed with excess hexane molecules at a cryogenic temperature of 20 K in a vacuum system. The solid matrix samples containing C8H2, C10H2, and C12H2 molecules were irradiated with UV laser pulses and the phosphorescence 0–0 band was observed at 532, 605, and 659 nm, respectively. Vibrational progression was observed for the symmetric stretching mode of the carbon chain in the ground state with increments of ~2190 cm−1 for C8H2, ~2120 cm−1 for C10H2, and ~2090 cm−1 for C12H2. Temporal decay analysis of the phosphorescence intensity revealed the lifetimes of the triplet state as ~30 ms for C8H2, ~8 ms for C10H2, and ~4 ms for C12H2. The phosphorescence excitation spectrum reproduces UV absorption spectra in the hexane solution and in the gas phase at ambient temperature, although the excitation energy was redshifted. The symmetry-forbidden vibronic transitions were observed for C10H2 by lower excitation energies of 25,500–31,000 cm−1 (320–390 nm). Detailed phosphorescence excitation patterns are discussed along the interaction of the polyyne molecule and solvent molecules of hexane.

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Hoerner, Paul, Wen Li et H. Bernhard Schlegel. « Sequential double ionization of molecules by strong laser fields simulated with time-dependent configuration interaction ». Journal of Chemical Physics 155, n^o 11 (21 septembre 2021) : 114103. http://dx.doi.org/10.1063/5.0060365.

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Ternovsky, E., A. Glushkov, A. Svinarenko et Yu Bunyakova. « Spectroscopy and kinetics of IR laser interaction with atmospheric molecules : Effects of cooling and chaos ». Journal of Physics : Conference Series 1412 (janvier 2020) : 132050. http://dx.doi.org/10.1088/1742-6596/1412/13/132050.

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Lutoshkin, V. I. « Analysis of the interaction between molecules and IR-laser radiation using one-dimensional lie groups ». Theoretical and Experimental Chemistry 31, n^o 4 (juillet 1995) : 189–95. http://dx.doi.org/10.1007/bf01195925.

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Nagaev, Egor I., Ilya V. Baimler, Alexey S. Baryshev, Veronika E. Reut et Maxim E. Astashev. « Interaction of Nd:YAG Laser Radiation with Bovine Serum Albumin Solution ». BIO Web of Conferences 57 (2023) : 02006. http://dx.doi.org/10.1051/bioconf/20235702006.

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In this paper, the effect of Nd:YAG laser radiation on the properties of the BSA protein is investigated. A solution with a protein concentration of 5 mg/ml was irradiated for 30 minutes. After a 5-minute and 30-minute exposure, absorption spectra were taken, the particle size in the solution was determined by dynamic light scattering (DLS), the refractive index was determined, and fluorescent maps were taken. Raman spectroscopy of proteins was also performed. The results showed that after irradiation, the absorption of the protein solution decreases in the spectral range corresponding to amino acid residues. In DLS experiments, it was shown that the peak corresponding to protein molecules decreases, and the peaks corresponding to large aggregates (>100 nm) grow. Raman spectroscopy has shown that there is a decrease in intensity at a wavelength of 1570 cm-1. There were no significant changes in the refractive indices and the shape of the fluorescent maps. The data suggest that partial denaturation of proteins took place.

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Litvinov, Rustem I., Oleg V. Gorkun, Scott F. Owen, Henry Shuman et John W. Weisel. « Binding Site Specificity, Mechanics, and Kinetics of Bimolecular Interactions Underlying Fibrin Polymerization. » Blood 106, n^o 11 (16 novembre 2005) : 1955. http://dx.doi.org/10.1182/blood.v106.11.1955.1955.

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Abstract Using laser tweezers-based force spectroscopy, we studied the rupture force profile of complementary interactions between individual fibrin(ogen) molecules and their fragments bearing variable sets of exposed binding sites. The technique of optically trapping and manipulating small particles using a focused laser beam, named laser tweezers, can measure external forces applied to the particle with extremely high resolution and is accurate at the lower end of the force spectrum (0–200 pN), which is suitable to quantify non-covalent intermolecular binding. Accordingly, we have developed an oscillating trap-based model system to study statistical distributions of rupture forces reflecting the whole variety of protein-protein interactions during repeated intermittent contact of surface-bound molecules. Based on several criteria that have been proposed to test whether the observed ruptures were due to the attachments of single or multiple pairs of molecules (PNAS2002, 99:7426; J. Biol. Chem. 2003, 278:51285), our data indicate that under the experimental conditions studied the rupture events are due to single bimolecular attachments. Fibrinogen and fibrinogen fragment D were used as the source of a- and b-holes, and fibrin monomer and fibrin monomer fragment N-DSK (N-terminal disulfide knot) were the source of A- and B-knobs. To distinguish between specific and non-specific binding, two types of control experiments were performed in which the specific interactions were suppressed by either replacing one of the interacting molecules with an inert protein or adding the peptide GPRPam, an inhibitor of fibrin polymerization. Exposure of A-knobs in desA-fibrin or its N-DSK fragment from the central part of the molecule resulted in strong interactions with fibrinogen or fragment D (containing only a- and b-holes), producing a binding strength of ~125–130 pN. The interactions were not present in the absence of either knobs or holes and were abrogated by a specific inhibitor of fibrin polymerization, a peptide mimic of the A-knob (GPRPam). Exposure of both the A- and B-knobs in desAB-fibrin or desAB-NDSK did not change the rupture force spectra compared to the desA-molecules, and their interactions with fibrinogen remained highly sensitive to GPRPam but not to GHRPam (B-knob), suggesting that neither A-b nor B-b nor B-a contacts contributed significantly to binding strength in addition to A-a contacts. Using recombinant fibrinogen mutants with impaired a-sites (γD364H, γD364A) or b-sites (BβD398A) confirmed this conclusion, however, revealed additional weak intermolecular interaction not related to knobs and holes. The A-a interactions had a relatively small zero-force off-rate of ~10−4 s−1 and tight knob-hole contacts characterized by a transition state distance of ~0.3 nm. The results demonstrate that the knob-to-hole binding during thrombin-induced fibrin polymerization is driven by strong, stable, and highly specific A-a bonding, while A-b, B-b, or B-a interactions were not detected. These data provide the molecular mechanisms for mechanical strength and thermodynamic stability of fibrin fibers enabling the accomplishment of physiological functions of a fibrin clot.

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Matic, Milan, Bogosav Lazetic, Mirjana Poljacki, Verica Djuran et Milana Ivkov-Simic. « Low level laser therapy and its effects on reparatory processes of the skin ». Medical review 56, n^o 3-4 (2003) : 137–41. http://dx.doi.org/10.2298/mpns0304137m.

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Introduction Application of laser beams for therapeutic purposes is of relatively recent date, but today there is no field of medicine where lasers cannot be used. Physical characteristics of laser radiation Laser radiation is a type of electromagnetic radiation with some specific characteristics such as coherence, monochromaticity and parallelity. Types of laser devices Nowadays, there are many laser devices on the market used in medicine and dentistry. According to the type of their active medium, lasers can be classified as solid, gas, semiconductor and liquid. Effects of low level laser therapy on biological systems The exact mechanism of action of low level laser therapy is still not completely understood. Its basic feature is to modulate cell behaviour, without causing significant temperature increase. During irradiation of a tissue with a laser beam, an interaction between cells and photons takes place - photochemical reaction. After a cell absorbs the photon, the photon stops existing, and its energy is incorporated into the molecule which has absorbed it. Once this energy is transferred to different bio-molecules, it can be transferred to other molecules as well. The energy transferred to the molecule can increase its kinetic energy, and activate or deactivate enzymes or alter physical or chemical properties of main macromolecules. Effects of low level laser therapy on wound healing Effects of low level laser therapy on wound healing process is one of the most fully studied aspects of this type of therapy. It affects all phases of this very complex process. This paper offers a more detailed analysis of these aspects.

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Friedrich, Břetislav, Manish Gupta et Dudley Herschbach. « Probing Weakly-Bound Species with Nonresonant Light : Dissociation of He2Induced by Rotational Hybridization ». Collection of Czechoslovak Chemical Communications 63, n^o 8 (1998) : 1089–93. http://dx.doi.org/10.1135/cccc19981089.

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A field-dependent value of angular momentum can be imparted to a 4He2 cluster by the interaction of its anisotropic polarizability with a nonresonant laser field. In this way a centrifugal term is introduced that can be tuned to a critical value sufficient to overcome the potential that binds the dimer. Due to its dependence on the internuclear distance and laser intensity, the critical angular momentum for dissociation is attained at different internuclear separations for different pulsed-laser intensities. As a result, the dependence of the dissociation probability on the laser intensity offers a means to map the potential and/or the polarizability anisotropy. A comparison with experiment thus could provide a test of either. The technique is applicable to other molecules in bound states close to the dissociation limit.

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Gylmiyarova, F. N., V. M. Radomskaya, O. A. Gusyakova, E. A. Ryskina, N. A. Kolotyeva, E. A. Shahnovich, N. S. Nefedova et al. « Modeling role of pyruvate in the processes of protein-protein interaction ». Biomeditsinskaya Khimiya 61, n^o 1 (janvier 2015) : 132–40. http://dx.doi.org/10.18097/pbmc20156101132.

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Using the ABO antibody-antigen model the influence of natural metabolite pyruvate on the antibody interaction with of erythrocyte antigens, defining their group specificity has been investigated. Before agglutination reaction erythrocytes of A(II)-AB(IV) blood groups, monoclonal anti-A and anti-B antibodies were incubated with sodium pyruvate. Visualization of agglutinates was performed by means of flow cytometry and laser scanning confocal microscopy. Computer-aided prediction of the spectrum of biological activity of pyruvate by a PASS program proposed major regulatory pathways, in which pyruvate may be involved. It has been demonstrated that pyruvate can regulate the intensity of antigen-antibody interaction. These results suggest the possibility of using small molecules, for example pyruvate, as molecular probes and prospects of the use of erythrocytes with antigenic determinants of the ABO system expressed on their membranes for studies of protein-protein interactions due to convenient visualization and possibility of quantitative evaluation of this process.

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Zavatski, Sergey, Nadia Khinevich, Kseniya Girel, Sergey Redko, Nikolai Kovalchuk, Ivan Komissarov, Vladimir Lukashevich et al. « Surface Enhanced Raman Spectroscopy of Lactoferrin Adsorbed on Silvered Porous Silicon Covered with Graphene ». Biosensors 9, n^o 1 (28 février 2019) : 34. http://dx.doi.org/10.3390/bios9010034.

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We registered surface enhanced Raman scattering (SERS) spectra of the human lactoferrin molecules adsorbed on a silvered porous silicon (por-Si) from 10−6–10−18 M solutions. It was found that the por-Si template causes a negative surface potential of silver particles and their chemical resistivity to oxidation. These properties provided to attract positively charged lactoferrin molecules and prevent their interaction with metallic particles upon 473 nm laser excitation. The SERS spectra of lactoferrin adsorbed from 10−6 M solution were rather weak but a decrease of the concentration to 10−10 M led to an enormous growth of the SERS signal. This effect took place as oligomers of lactoferrin were broken down to monomeric units while its concentration was reduced. Oligomers are too large for a uniform overlap with electromagnetic field from silver particles. They cannot provide an intensive SERS signal from the top part of the molecules in contrast to monomers that can be completely covered by the electromagnetic field. The SERS spectra of lactoferrin at the 10−14 and 10−16 M concentrations were less intensive and started to change due to increasing contribution from the laser burned molecules. To prevent overheating the analyte molecules on the silvered por-Si were protected with graphene, which allowed the detection of lactoferrin adsorbed from the 10−18 M solution.

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Plancque, Gabriel, Yoann Maurice, Valérie Moulin, Pierre Toulhoat et Christophe Moulin. « On the Use of Spectroscopic Techniques for Interaction Studies, Part I : Complexation between Europium and Small Organic Ligands ». Applied Spectroscopy 59, n^o 4 (avril 2005) : 432–41. http://dx.doi.org/10.1366/0003702053641540.

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In the framework of environmental studies, it is important to understand the interaction of humic substances with cations (heavy metals, radionuclides) and to determine their complexation constants in order to evaluate their potential impact on their fate. For this purpose, two techniques have been used: electrospray ionization mass spectrometry, a newly used technique in speciation studies, and time-resolved laser-induced fluorescence spectrometry, a well-known technique for such studies. As a first step, for simplification purposes and to compare both techniques, simple molecules having functional groups present in humic substances have been selected, such as acetic, glycolic, and 4-hydroxyphenylacetic acids. Both techniques have been used to obtain stoichiometries and complexation constants between these simple molecules and europium (III).

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PEI, PEI, CHONG LI et HE-SHAN SONG. « ENTANGLEMENT DYNAMICS IN ROVIBRATIONAL MOLECULES DRIVEN BY INFRARED PULSES ». International Journal of Quantum Information 08, n^o 06 (septembre 2010) : 937–45. http://dx.doi.org/10.1142/s0219749910006654.

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We studied the dynamics of entanglement in ultra-cold heteronuclear diatomic rovibrational molecules driven by an infrared laser field. Environment-induced spontaneous emission is considered. Numerical results show that the resonant external field and damping processes can bring into equilibrium and the disentanglement can be suppressed evidently. Appropriate intensity of far detuned pulses can also suppress disentanglement and produce some entanglement if there is initially separable state, but damping processes and interaction via polarizability dominate the disentanglement, leading to the vanishing of entanglement after a long time.

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Hayat, Zain, et Abdel El Abed. « First Experimental Evidence of Anti-Stokes Laser-Induced Fluorescence Emission in Microdroplets and Microfluidic Systems Driven by Low Thermal Conductivity of Fluorocarbon Carrier Oil ». Micromachines 14, n^o 4 (29 mars 2023) : 765. http://dx.doi.org/10.3390/mi14040765.

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With the advent of many optofluidic and droplet microfluidic applications using laser-induced fluorescence (LIF), the need for a better understanding of the heating effect induced by pump laser excitation sources and good monitoring of temperature inside such confined microsystems started to emerge. We developed a broadband highly sensitive optofluidic detection system, which enabled us to show for the first time that Rhodamine-B dye molecules can exhibit standard photoluminescence as well as blue-shifted photoluminescence. We demonstrate that this phenomenon originates from the interaction between the pump laser beam and dye molecules when surrounded by the low thermal conductive fluorocarbon oil, generally used as a carrier medium in droplet microfluidics. We also show that when the temperature is increased, both Stokes and anti-Stokes fluorescence intensities remain practically constant until a temperature transition is reached, above which the fluorescence intensity starts to decrease linearly with a thermal sensitivity of about −0.4%/°C for Stokes emission or −0.2%/°C for anti-Stokes emission. For an excitation power of 3.5 mW, the temperature transition was found to be about 25 °C, whereas for a smaller excitation power (0.5 mW), the transition temperature was found to be about 36 °C.

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Kemp, Terence J., Anthony W. Parker et Peter Wardman. « Interaction of triplet-state nucleic acid bases with electroaffinic molecules in solution by laser flash photolysis ». Journal of the Chemical Society, Perkin Transactions 2, n^o 3 (1987) : 397. http://dx.doi.org/10.1039/p29870000397.

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Häger, J. « Laser investigation of the dynamics of molecule–surface interaction : Rotational and translational energy of scattered molecules ». Journal of Vacuum Science & ; Technology B : Microelectronics and Nanometer Structures 3, n^o 5 (septembre 1985) : 1490. http://dx.doi.org/10.1116/1.582973.

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Watt, Lewis G., Sam Crawshaw, Sun-Ju Rhee, Alex M. Murphy, Tomás Canto et John P. Carr. « The cucumber mosaic virus 1a protein regulates interactions between the 2b protein and ARGONAUTE 1 while maintaining the silencing suppressor activity of the 2b protein ». PLOS Pathogens 16, n^o 12 (3 décembre 2020) : e1009125. http://dx.doi.org/10.1371/journal.ppat.1009125.

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The cucumber mosaic virus (CMV) 2b viral suppressor of RNA silencing (VSR) is a potent counter-defense and pathogenicity factor that inhibits antiviral silencing by titration of short double-stranded RNAs. It also disrupts microRNA-mediated regulation of host gene expression by binding ARGONAUTE 1 (AGO1). But in Arabidopsis thaliana complete inhibition of AGO1 is counterproductive to CMV since this triggers another layer of antiviral silencing mediated by AGO2, de-represses strong resistance against aphids (the insect vectors of CMV), and exacerbates symptoms. Using confocal laser scanning microscopy, bimolecular fluorescence complementation, and co-immunoprecipitation assays we found that the CMV 1a protein, a component of the viral replicase complex, regulates the 2b-AGO1 interaction. By binding 2b protein molecules and sequestering them in P-bodies, the 1a protein limits the proportion of 2b protein molecules available to bind AGO1, which ameliorates 2b-induced disease symptoms, and moderates induction of resistance to CMV and to its aphid vector. However, the 1a protein-2b protein interaction does not inhibit the ability of the 2b protein to inhibit silencing of reporter gene expression in agroinfiltration assays. The interaction between the CMV 1a and 2b proteins represents a novel regulatory system in which specific functions of a VSR are selectively modulated by another viral protein. The finding also provides a mechanism that explains how CMV, and possibly other viruses, modulates symptom induction and manipulates host-vector interactions.

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Longtin, J. P., et C. L. Tien. « Saturable Absorption During High-Intensity Laser Heating of Liquids ». Journal of Heat Transfer 118, n^o 4 (1 novembre 1996) : 924–30. http://dx.doi.org/10.1115/1.2822590.

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The interaction of high-intensity, short-pulse laser radiation with liquids is fundamental to many contemporary technologies. At low laser intensities, the classical model of absorption and heating applies, which assumes a constant absorption coefficient and no dependence on intensity. As the intensity increases, however, many molecules are promoted to excited states, whose absorption properties differ from those of the ground state, and the absorption of the bulk liquid is altered. This phenomenon, called saturable absorption, results in intensity-dependent absorption, heating, and temperature distributions that can deviate significantly from classical absorption. This work investigates the thermal aspects of saturable absorption during laser heating of liquids. A microscopically based model of the radiation absorption and heating processes is presented. Model solutions are discussed and compared with experiment for a contemporary saturable absorbing liquid. Simple engineering criteria and relevant applications are then discussed.

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Pan, Shengzhe, Chenxi Hu, Zhaohan Zhang, Peifen Lu, Chenxu Lu, Lianrong Zhou, Jiawei Wang et al. « Low-Energy Protons in Strong-Field Dissociation of H₂⁺ via Dipole-Transitions at Large Bond Lengths ». Ultrafast Science 2022 (5 mai 2022) : 1–9. http://dx.doi.org/10.34133/2022/9863548.

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More than ten years ago, the observation of the low-energy structure in the photoelectron energy spectrum, regarded as an “ionization surprise,” has overthrown our understanding of strong-field physics. However, the similar low-energy nuclear fragment generation from dissociating molecules upon the photon energy absorption, one of the well-observed phenomena in light-molecule interaction, still lacks an unambiguous mechanism and remains mysterious. Here, we introduce a time-energy-resolved manner using a multicycle near-infrared femtosecond laser pulse to identify the physical origin of the light-induced ultrafast dynamics of molecules. By simultaneously measuring the bond-stretching times and photon numbers involved in the dissociation of H2+ driven by a polarization-skewed laser pulse, we reveal that the low-energy protons (below 0.7 eV) are produced via dipole-transitions at large bond lengths. The observed low-energy protons originate from strong-field dissociation of high vibrational states rather than the low ones of H2+ cation, which is distinct from the well-accepted bond-softening picture. Further numerical simulation of the time-dependent Schrödinger equation unveils that the electronic states are periodically distorted by the strong laser field, and the energy gap between the field-dressed transient electronic states may favor the one- or three-photon transitions at the internuclear distance larger than 5 a.u. The time-dependent scenario and our time-energy-resolved approach presented here can be extended to other molecules to understand the complex ultrafast dynamics.

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Salam, A. « Electric Octupole-Dependent Contributions to Optical Binding Energy ». Physics 6, n^o 1 (6 mars 2024) : 376–93. http://dx.doi.org/10.3390/physics6010025.

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Contributions to the radiation-induced dispersion energy shift between two interacting particles dependent on the electric octupole moment are calculated using a physical picture in which moments induced by applied fluctuating electromagnetic fields are coupled via retarded interaction tensors. The specific potentials evaluated include those found between an electric dipole-polarisable molecule and either a mixed electric dipole–octupole- or purely octupole-polarisable molecule, and those between two mixed electric dipole–octupole-polarisable molecules. Interaction energies are obtained for molecular and pair orientationally averaged situations. Terms dependent on the octupole weight-1 moment may be viewed as higher-order corrections to the leading dipole–dipole interaction energy as also found in energy transfer and dispersion forces. A comprehensive polarisation analysis is carried out for linearly and circularly polarised laser light incident parallel and perpendicular to the inter-particle axis. Contributions to the optical binding energy arising when one of the pair is polar and characterised by either a permanent electric dipole or octupole moment are also evaluated. Neither of these energy shifts survive orientational averaging.

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Nilar, Shahul H., Ajit J. Thakkar, Anne E. Kondo et William J. Meath. « Electronic energies, dipole moment matrix elements, and static polarizabilities and hyperpolarizabilities for some diphenyl molecules ». Canadian Journal of Chemistry 71, n^o 10 (1 octobre 1993) : 1663–71. http://dx.doi.org/10.1139/v93-207.

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The "giant dipole" molecules, NR1R2—C6H4—(C≡C)n—C6H4—NO2n = 0, 1, 2, are studied theoretically for three sets of substituents: R1 = R2 = H, R1 = H, R2 = CH3, and R1 = R2 = CH3. For each of these nine molecules, the energies, and permanent and transition dipole moments for the 20 lowest electronic states are calculated using the intermediate neglect of differential overlap (INDO) approximation at the configuration interaction with single excitations (CIS) level. Static polarizabilities and hyperpolarizabilities for the ground states are reported for these "push–pull" molecules. The changes in the physical properties of interest due to increase in conjugation length and the inductive effect of substituents on the donor group attached to the rings are discussed. The energies and permanent and transition dipole moments for the ten lowest electronic states are tabulated for use in future studies of the spectral and dynamical effects of permanent dipoie moments on laser-induced one- and multi-photon electronic transitions in realistic models for many-level giant dipole molecules.

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