Статті в журналах: "Probing Exciton Dynamics"

1

Pan, Jie. "Computationally probing exciton dynamics." Nature Computational Science 1, no. 4 (April 2021): 246. http://dx.doi.org/10.1038/s43588-021-00065-4.

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2

Zhao, Siqi, Dawei He, Jiaqi He, Xinwu Zhang, Lixin Yi, Yongsheng Wang, and Hui Zhao. "Probing excitons in transition metal dichalcogenides by Drude-like exciton intraband absorption." Nanoscale 10, no. 20 (2018): 9538–46. http://dx.doi.org/10.1039/c8nr03135e.

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3

Tikhomirov, S. A. "Ultrafast dynamics and mechanisms of non-stationary absorption in thin gallium selenide samples." Proceedings of the National Academy of Sciences of Belarus. Physics and Mathematics Series 57, no. 1 (April 2, 2021): 99–107. http://dx.doi.org/10.29235/1561-2430-2021-57-1-99-107.

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Herein, the dynamics and mechanisms of induced absorption in thin samples of gallium selenide under various excitation conditions are studied using femtosecond kinetic spectroscopy. We have registered several types of induced changes including induced absorption on free charge carriers (“hot” and thermalized electrons), bleaching and absorption due to the population of near-edge trap or exciton states, as well as rapid changes in the absorption of probing radiation in the region of the overlap of the exciting and probing pulses due to two-quantum two-frequency interband transitions. The time ranges of the relaxation processes are estimated. It is shown that when using relatively low-intensity long-wave excitation (790 nm), the resonant excitation of the near-edge states occurs mainly due to two-quantum two-frequency transitions followed by the formation of the dynamic equilibrium between bound and free electrons in the time range up to 5 ps. When electrons are excited deeply into the conduction band with the formation of hot free electrons and their subsequent thermalization to the bottom of the conduction band in the time range up to 1 ps, the population of the near-edge states and the establishment of the dynamic equilibrium between bound and free electrons is realized in the same time range (5 ps) as when they are excited “from below”.

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4

Somoza Márquez, Alejandro, Lipeng Chen, Kewei Sun, and Yang Zhao. "Probing ultrafast excitation energy transfer of the chlorosome with exciton–phonon variational dynamics." Physical Chemistry Chemical Physics 18, no. 30 (2016): 20298–311. http://dx.doi.org/10.1039/c5cp06491k.

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5

Bock, A. M., D. Schmid, and C. Kryschi. "Femtosecond probing of singlet exciton dynamics in polybithiophene films." Radiation Effects and Defects in Solids 155, no. 1-4 (November 2001): 299–303. http://dx.doi.org/10.1080/10420150108214128.

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6

Gdor, I., H. Sachs, A. Roitblat, D. Strasfeld, M. G. Bawendi, and S. Ruhman. "Hyperspectral Probing of Exciton dynamics and Multiplication in PbSe Nanocrystals." EPJ Web of Conferences 41 (2013): 04037. http://dx.doi.org/10.1051/epjconf/20134104037.

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7

Yan, Tengfei, Hongyi Yu, Ke Xiao, Wang Yao, and Xiaodong Cui. "Probing the exciton k-space dynamics in monolayer tungsten diselenides." 2D Materials 6, no. 2 (March 15, 2019): 025035. http://dx.doi.org/10.1088/2053-1583/ab0a4e.

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8

Bock, Alexander M., Dankward Schmid, and Carola Kryschi. "Femtosecond probing of exciton relaxation and transport dynamics in polybithiophene." Journal of Chemical Physics 111, no. 3 (July 15, 1999): 1185–90. http://dx.doi.org/10.1063/1.479303.

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9

Korotkevich, Alexander A., and Huib J. Bakker. "Ultrafast vibrational dynamics of aqueous acetate and terephthalate." Journal of Chemical Physics 156, no. 9 (March 7, 2022): 094501. http://dx.doi.org/10.1063/5.0082462.

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We study the vibrational population relaxation and mutual interaction of the symmetric stretch ( ν s) and antisymmetric stretch ( ν as) vibrations of the carboxylate anion groups of acetate and terephthalate ions in aqueous solution by femtosecond two-dimensional infrared spectroscopy. By selectively exciting and probing the ν s and ν as vibrations, we find that the interaction of the two vibrations involves both the anharmonic coupling of the vibrations and energy exchange between the excited states of the vibrations. We find that both the vibrational population relaxation and the energy exchange are faster for terephthalate than for acetate.

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10

Leone, Stephen R., and Daniel M. Neumark. "Probing matter with nonlinear spectroscopy." Science 379, no. 6632 (February 10, 2023): 536–37. http://dx.doi.org/10.1126/science.add4509.

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11

Herman, Artur P., Szymon J. Zelewski, Kamil Misztal, and Robert Kudrawiec. "Probing the long-lived photo-generated charge carriers in transition metal dichalcogenides by time-resolved microwave photoconductivity." Nanophotonics 11, no. 7 (February 24, 2022): 1335–44. http://dx.doi.org/10.1515/nanoph-2021-0741.

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Abstract Understanding the dissociation of excitons into long-lived free charge carriers is a crucial issue when considering the applications of transition metal dichalcogenides (excitonic semiconductors) oriented toward the use of solar energy (such as photovoltaics or photocatalysis). In our work, long-lived carriers have been observed by time-resolved microwave photoconductivity (TRMC) for the first time in both atomically thin and bulk MoS2, MoSe2, WS2, and WSe2 crystals. The lifetime of majority carriers is close to microseconds and can even reach several microseconds due to different contribution of surface and defect states, as well as surface band bending (bulk). The three components depend on the material and vary from sample to sample, therefore determining the dynamics of the TRMC signal. The rise time of TRMC signal was found to be in the range of 0.1–0.2 μs and as it depends on the studied material it can be speculated that it is related to the dissociation time of excitons captured by traps.

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12

Röttger, Katharina, Hugo J. B. Marroux, Hendrik Böhnke, David T. J. Morris, Angus T. Voice, Friedrich Temps, Gareth M. Roberts, and Andrew J. Orr-Ewing. "Probing the excited state relaxation dynamics of pyrimidine nucleosides in chloroform solution." Faraday Discussions 194 (2016): 683–708. http://dx.doi.org/10.1039/c6fd00068a.

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Ultrafast transient electronic and vibrational absorption spectroscopy (TEAS and TVAS) of 2′-deoxy-cytidine (dC) and 2′-deoxy-thymidine (dT) dissolved in chloroform examines their excited-state dynamics and the recovery of ground electronic state molecules following absorption of ultraviolet light. The chloroform serves as a weakly interacting solvent, allowing comparisons to be drawn with prior experimental studies of the photodynamics of these nucleosides in the gas phase and in polar solvents such as water. The pyrimidine base nucleosides have some propensity to dimerize in aprotic solvents, but the monomer photochemistry can be resolved clearly and is the focus of this study. UV absorption at a wavelength of 260 nm excites a ¹ππ* ← S₀ transition, but prompt crossing of a significant fraction (50% in dC, 17% in dT) of the ¹ππ* population into a nearby ¹nπ* state is too fast for the experiments to resolve. The remaining flux on the ¹ππ* state leaves the vertical Franck–Condon region and encounters a conical intersection with the ground electronic state of ethylenic twist character. In dC, the ¹ππ* state decays to the ground state with a time constant of 1.1 ± 0.1 ps. The lifetime of the ¹nπ* state is much longer in the canonical forms of both molecules: recovery of the ground state population from these states occurs with time constants of 18.6 ± 1.1 ps in amino-oxo dC and ∼114 ps in dT, indicating potential energy barriers to the ¹nπ*/S₀ conical intersections. The small fraction of the imino-oxo tautomer of dC present in solution has a longer-lived ¹nπ* state with a lifetime for ground state recovery of 193 ± 55 ps. No evidence is found for photo-induced tautomerization of amino-oxo dC to the imino-oxo form, or for population of low lying triplet states of this nucleoside. In contrast, ∼8% of the UV-excited dT molecules access the long-lived T₁ (³ππ*) state through the ¹nπ* state. The primary influence of the solvent appears to be the degree to which it destabilizes the states of ¹nπ* character, with consequences for the lifetimes of these states as well as the triplet state yields.

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13

Bratos, S., and J. Cl Leicknam. "Convolution Problems in Time-Resolved X-Ray Diffraction." Ukrainian Journal of Physics 57, no. 2 (February 15, 2012): 133. http://dx.doi.org/10.15407/ujpe57.2.133.

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Convolution problems in the time-resolved scattering of 10–1000-ps x-ray pulses are studied theoretically. The model system is a diluted solution of diatomic molecules A2 dissolved in an inert solvent. This system is submitted to a sub-picosecond laser pulse, which promotes the molecules A2 into an excited electronic state. The molecule then return into their ground state, passing through several intermediate electronic states. The effects of the finite duration of probing x-ray pulses on various x-ray signals are then examined in the frame of this model. Unbiased signals generated by very short x-ray pulses are explored first. Variations of a molecular geometry during this process are clearly visible in r-resolved, but are less explicit in q-resolved signals. The signals measured with x-ray pulses of a finite duration are studied next. Atomic motions remain detectable, but only if the x-ray pulses are shorter than or comparable to the times of a molecular dynamics. Here again, the r-resolved signals are more appropriate for monitoring the molecular dynamics than q-resolved signals. Finally, the effect of the insufficient temporal location of probing x-ray pulses with respect to that of exciting laser pulses is examined. It is shown that this last effect can be accounted for by simply replacing the true x-ray pulse intensity by another theoretically predicted intensity. The similarity of deconvolution techniques in spectroscopy and in time-resolved x-ray diffraction is strongly emphasized.

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14

Papadopoulou, C. C., S. Kaziannis, and C. Kosmidis. "Probing the dynamics of highly excited toluene on the fs timescale." Physical Chemistry Chemical Physics 17, no. 47 (2015): 31727–34. http://dx.doi.org/10.1039/c5cp04346h.

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15

Aseyev, Sergei A., Anatoly A. Ischenko, Igor V. Kochikov, Boris N. Mironov, Evgeny A. Ryabov, Yury A. Zhabanov, Victor O. Kompanets, Aleksandr L. Malinovskii, Arseniy A. Otlyotov, and Sergei V. Chekalin. "4D-Structural Dynamics of the Transition State: Free Molecules, Clusters and Nanocrystals." Vestnik RFFI, no. 3 (July 31, 2019): 107–28. http://dx.doi.org/10.22204/2410-4639-2019-103-03-107-128.

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Study of the structural dynamics of matter by methods with high spatially-temporal resolution represents new direction in modern science and provides the understanding of relationship inside the "structure – dynamics – property" triad in the field of physics, chemistry, biology and materials science. Application of femto and attosecond laser pulses for excitation and formation of synchronized ultrashort photoelectron bunches for probing makes it possible to observe coherent dynamics of nuclei and electrons in samples on necessary space-time scales. Using laser spectroscopy one can determine energy levels of the sample and trace their evolution over time. However, the extraction of the structural dynamics of matter from this information is achieved by indirect methods. In the paper authors demonstrate the direct approaches to the study of the coherent dynamics of the nuclei of laser-excited matter in the space-time continuum (4D), based on probing the object with ultra-short electron or X-ray pulses, and describe their experiments, which were carried out using ultrafast electron diffractometer and transmission electron microscope at the Institute of Spectroscopy RAS.

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16

Johansson, J. O., J. W. Kim, E. Allwright, D. M. Rogers, N. Robertson, and J. Y. Bigot. "Directly probing spin dynamics in a molecular magnet with femtosecond time-resolution." Chemical Science 7, no. 12 (2016): 7061–67. http://dx.doi.org/10.1039/c6sc01105e.

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17

Penfold, T. J., M. Pápai, T. Rozgonyi, K. B. Møller, and G. Vankó. "Probing spin–vibronic dynamics using femtosecond X-ray spectroscopy." Faraday Discussions 194 (2016): 731–46. http://dx.doi.org/10.1039/c6fd00070c.

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Ultrafast pump-probe spectroscopy within the X-ray regime is now possible owing to the development of X-ray Free Electrons Lasers (X-FELs) and is opening new opportunities for the direct probing of femtosecond evolution of the nuclei, the electronic and spin degrees of freedom. In this contribution we use wavepacket dynamics of the photoexcited decay of a new Fe(ii) complex, [Fe(bmip)₂]²⁺ (bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)pyridine), to simulate the experimental observables associated with femtosecond Fe K-edge X-ray Absorption Near-Edge Structure (XANES) and X-ray emission (XES) spectroscopy. We show how the evolution of the nuclear wavepacket is translated into the spectroscopic signal and the sensitivity of these approaches for following excited state dynamics.

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18

Lindsay, Stuart, and Judy Zhu. "Probing the Liquid-Solid Interface with Dynamic Force Microscopy." Microscopy Today 7, no. 8 (October 1999): 12–18. http://dx.doi.org/10.1017/s1551929500064993.

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Processes at real interfaces, such as drug dissolution, corrosion, enzyme activity and surfactant structure can now be studied with nanometer resolution using dynamic force microscopy. Optimal sensitivity is achieved when the tip is excited by direct application of a driving force using magnetic methods.

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19

Ghosh, Rajib, and Dipak K. Palit. "Probing excited state charge transfer dynamics in a heteroleptic ruthenium complex." Phys. Chem. Chem. Phys. 16, no. 1 (2014): 219–26. http://dx.doi.org/10.1039/c3cp53886a.

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20

Gierz, I. "Probing carrier dynamics in photo-excited graphene with time-resolved ARPES." Journal of Electron Spectroscopy and Related Phenomena 219 (August 2017): 53–56. http://dx.doi.org/10.1016/j.elspec.2016.11.001.

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21

Sekhar, Ashok, Jessica A. O. Rumfeldt, Helen R. Broom, Colleen M. Doyle, Ryan E. Sobering, Elizabeth M. Meiering, and Lewis E. Kay. "Probing the free energy landscapes of ALS disease mutants of SOD1 by NMR spectroscopy." Proceedings of the National Academy of Sciences 113, no. 45 (October 24, 2016): E6939—E6945. http://dx.doi.org/10.1073/pnas.1611418113.

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Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that, in some cases, has been linked with mutations to the antioxidant metalloenzyme superoxide dismutase (SOD1). Although the mature form of this enzyme is highly stable and resistant to aggregation, the most immature form, lacking metal and a stabilizing intrasubunit disulfide bond, apoSOD12SH, is dynamic and hypothesized to be a major cause of toxicity in vivo. Previous solution NMR studies of wild-type apoSOD12SH have shown that the ground state interconverts with a series of sparsely populated and transiently formed conformers, some of which have aberrant nonnative structures. Here, we study seven disease mutants of apoSOD12SH and characterize their free energy landscapes as a first step in understanding the initial stages of disease progression and, more generally, to evaluate the plasticity of low-lying protein conformational states. The mutations lead to little change in the structures and dynamics of the ground states of the mutant proteins. By contrast, the numbers of low-lying excited states that are accessible to each of the disease mutants can vary significantly, with additional conformers accessed in some cases. Our study suggests that the diversity of these structures can provide alternate interaction motifs for different mutants, establishing additional pathways for new and often aberrant intra- and intermolecular contacts. Further, it emphasizes the potential importance of conformationally excited states in directing both folding and misfolding processes.

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22

Nenov, Artur, Javier Segarra-Martí, Angelo Giussani, Irene Conti, Ivan Rivalta, Elise Dumont, Vishal K. Jaiswal, Salvatore Flavio Altavilla, Shaul Mukamel, and Marco Garavelli. "Probing deactivation pathways of DNA nucleobases by two-dimensional electronic spectroscopy: first principles simulations." Faraday Discussions 177 (2015): 345–62. http://dx.doi.org/10.1039/c4fd00175c.

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The SOS//QM/MM [Rivalta et al., Int. J. Quant. Chem., 2014, 114, 85] method consists of an arsenal of computational tools allowing accurate simulation of one-dimensional (1D) and bi-dimensional (2D) electronic spectra of monomeric and dimeric systems with unprecedented details and accuracy. Prominent features like doubly excited local and excimer states, accessible in multi-photon processes, as well as charge-transfer states arise naturally through the fully quantum-mechanical description of the aggregates. In this contribution the SOS//QM/MM approach is extended to simulate time-resolved 2D spectra that can be used to characterize ultrafast excited state relaxation dynamics with atomistic details. We demonstrate how critical structures on the excited state potential energy surface, obtained through state-of-the-art quantum chemical computations, can be used as snapshots of the excited state relaxation dynamics to generate spectral fingerprints for different de-excitation channels. The approach is based on high-level multi-configurational wavefunction methods combined with non-linear response theory and incorporates the effects of the solvent/environment through hybrid quantum mechanics/molecular mechanics (QM/MM) techniques. Specifically, the protocol makes use of the second-order Perturbation Theory (CASPT2) on top of Complete Active Space Self Consistent Field (CASSCF) strategy to compute the high-lying excited states that can be accessed in different 2D experimental setups. As an example, the photophysics of the stacked adenine–adenine dimer in a double-stranded DNA is modeled through 2D near-ultraviolet (NUV) spectroscopy.

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23

Lampin, J. F., G. Mouret, S. Dhillon, and J. Mangeney. "THz spectroscopy for fundamental science and applications." Photoniques, no. 101 (March 2020): 33–38. http://dx.doi.org/10.1051/photon/202010133.

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Many elementary process in matter, such as the interaction of electrons, spins and phonons as well as rotational modes of molecules possess resonances frequencies in the THz spectral range (1 THz = 1012 Hz) and dynamics on (sub)-picosecond time scales. Therefore, THz spectroscopy has become an exciting technique for probing and characterizing a variety of low-energy physical phenomena [1], which makes it very attractive for a wide range of disciplines including physics, chemistry, astronomy, and medicine.

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24

Cai, Mengli, Ying Huang, Yang Shen, Min Li, Michiyo Mizuuchi, Rodolfo Ghirlando, Kiyoshi Mizuuchi, and G. Marius Clore. "Probing transient excited states of the bacterial cell division regulator MinE by relaxation dispersion NMR spectroscopy." Proceedings of the National Academy of Sciences 116, no. 51 (November 26, 2019): 25446–55. http://dx.doi.org/10.1073/pnas.1915948116.

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Bacterial MinD and MinE form a standing oscillatory wave which positions the cell division inhibitor MinC, that binds MinD, everywhere on the membrane except at the midpoint of the cell, ensuring midcell positioning of the cytokinetic septum. During this process MinE undergoes fold switching as it interacts with different partners. We explore the exchange dynamics between major and excited states of the MinE dimer in 3 forms using15N relaxation dispersion NMR: the full-length protein (6-stranded β-sheet sandwiched between 4 helices) representing the resting state; a 10-residue N-terminal deletion (Δ10) mimicking the membrane-binding competent state where the N-terminal helix is detached to interact with membrane; and N-terminal deletions of either 30 (Δ30) or 10 residues with an I24N mutation (Δ10/I24N), in which the β1-strands at the dimer interface are extruded and available to bind MinD, leaving behind a 4-stranded β-sheet. Full-length MinE samples 2 “excited” states: The first is similar to a full-length/Δ10 heterodimer; the second, also sampled by Δ10, is either similar to or well along the pathway toward the 4-stranded β-sheet form. Both Δ30 and Δ10/I24N sample 2 excited species: The first may involve destabilization of the β3- and β3′-strands at the dimer interface; changes in the second are more extensive, involving further disruption of secondary structure, possibly representing an ensemble of states on the pathway toward restoration of the resting state. The quantitative information on MinE conformational dynamics involving these excited states is crucial for understanding the oscillation pattern self-organization by MinD–MinE interaction dynamics on the membrane.

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25

El-Khoury, Patrick Z., Saju Joseph, Igor Schapiro, Samer Gozem, Massimo Olivucci, and Alexander N. Tarnovsky. "Probing Vibrationally Mediated Ultrafast Excited-State Reaction Dynamics with Multireference (CASPT2) Trajectories." Journal of Physical Chemistry A 117, no. 44 (October 23, 2013): 11271–75. http://dx.doi.org/10.1021/jp408441w.

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26

Neville, Simon P., Vitali Averbukh, Marco Ruberti, Renjie Yun, Serguei Patchkovskii, Majed Chergui, Albert Stolow, and Michael S. Schuurman. "Excited state X-ray absorption spectroscopy: Probing both electronic and structural dynamics." Journal of Chemical Physics 145, no. 14 (October 14, 2016): 144307. http://dx.doi.org/10.1063/1.4964369.

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27

Zhou, X., P. Ranitovic, C. W. Hogle, J. H. D. Eland, H. C. Kapteyn, and M. M. Murnane. "Probing and controlling non-Born–Oppenheimer dynamics in highly excited molecular ions." Nature Physics 8, no. 3 (January 29, 2012): 232–37. http://dx.doi.org/10.1038/nphys2211.

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28

Moroz, P., N. Kholmicheva, N. Razgoniaeva, D. Burchfield, N. Sharma, A. Acharya, and M. Zamkov. "Optical techniques for probing the excited state dynamics of quantum dot solids." Chemical Physics 471 (June 2016): 59–68. http://dx.doi.org/10.1016/j.chemphys.2015.08.001.

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29

McCormack, EF, ST Pratt, PM Dehmer, and JL Dehmer. "Excited-state Structure and Dynamics of Nitric Oxide probed by Resonant Four-wave Mixing Techniques." Australian Journal of Physics 49, no. 2 (1996): 445. http://dx.doi.org/10.1071/ph960445.

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We review the results from two experiments that used resonant four-wave mixing (RFWM) techniques to investigate double-resonance transitions in NO. In the first experiment, laserinduced grating decay curves that reveal quantum beats due to the hyperfine structure of the A 2Σ, υ' = 0 state were observed and interpreted. In the second, multistate interactions between the L 2II1/ 2,3/2, υ = 8 and Q 2II1/ 2,3/2, υ = 0 states were investigated, and new assignments were made. The results highlight the potential of RFWM techniques for probing excited-state physics.

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30

Rauthe, Pascal, Kristina Sabljo, Maike Kristin Vogelbacher, Claus Feldmann, and Andreas-Neil Unterreiner. "Excited State Dynamics of Alizarin Red S Nanoparticles in Solution." Molecules 28, no. 15 (July 25, 2023): 5633. http://dx.doi.org/10.3390/molecules28155633.

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Alizarin red S is a sulfonated, water-soluble derivative of alizarin. This work presents femtosecond studies of alizarin red S (ARS) nanoparticles in comparison to ARS in aqueous solution and to alizarin in DMSO. The femtosecond studies cover a probing spectral range of 350–750 nm using different excitation wavelengths, taking into account the variation of the absorption spectra with the pH values of the solvent. Stationary absorption spectra show slight differences between solution and nanoparticles. Excitation at 530 nm results in low and noisy responses, therefore, we additionally recorded transient spectra of the nanoparticles at λex = 267 nm. While the results in DMSO are comparable to previous studies in non-aqueous solvents, we report a relatively fast relaxation of 14 ps in [La(OH)2][ARS] nanoparticles in aqueous solution after excitation at 530 nm, which is similar to Na(ARS) solution (19 ps). The dynamics changed with lower pH, but still without significant differences between nanoparticles and solution. We propose [La(OH)2][ARS] nanoparticles as a suitable alternative to dissolved molecules with similar spectroscopic properties, for example, with regard to biomarker applications.

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31

Markwick, Phineus R. L., Nikos L. Doltsinis, and Jürgen Schlitter. "Probing irradiation induced DNA damage mechanisms using excited state Car-Parrinello molecular dynamics." Journal of Chemical Physics 126, no. 4 (January 28, 2007): 045104. http://dx.doi.org/10.1063/1.2431177.

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32

Ishizaki, Akihito. "Probing excited-state dynamics with quantum entangled photons: Correspondence to coherent multidimensional spectroscopy." Journal of Chemical Physics 153, no. 5 (August 7, 2020): 051102. http://dx.doi.org/10.1063/5.0015432.

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33

Bar, Ilana, and Salman Rosenwaks. "Controlling bond cleavage and probing intramolecular dynamics via photodissociation of rovibrationally excited molecules." International Reviews in Physical Chemistry 20, no. 4 (October 2001): 711–49. http://dx.doi.org/10.1080/01442350110076484.

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34

Robinson, Matthew Scott, Mario Niebuhr, and Markus Gühr. "Ultrafast Photo-Ion Probing of the Relaxation Dynamics in 2-Thiouracil." Molecules 28, no. 5 (March 3, 2023): 2354. http://dx.doi.org/10.3390/molecules28052354.

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In this work, we investigate the relaxation processes of 2-thiouracil after UV photoexcitation to the S2 state through the use of ultrafast, single-colour, pump-probe UV/UV spectroscopy. We place focus on investigating the appearance and subsequent decay signals of ionized fragments. We complement this with VUV-induced dissociative photoionisation studies collected at a synchrotron, allowing us to better understand and assign the ionisation channels involved in the appearance of the fragments. We find that all fragments appear when single photons with energy > 11 eV are used in the VUV experiments and hence appear through 3+ photon-order processes when 266 nm light is used. We also observe three major decays for the fragment ions: a sub-autocorrelation decay (i.e., sub-370 fs), a secondary ultrafast decay on the order of 300–400 fs, and a long decay on the order of 220 to 400 ps (all fragment dependent). These decays agree well with the previously established S2 → S1 → Triplet → Ground decay process. Results from the VUV study also suggest that some of the fragments may be created by dynamics occurring in the excited cationic state.

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35

Zhang, Wei, Jie Kong, Wenqi Xu, Xinmiao Niu, Di Song, Weimin Liu, and Andong Xia. "Probing effect of solvation on photoexcited quadrupolar donor-acceptor-donor molecule via ultrafast Raman spectroscopy." Chinese Journal of Chemical Physics 35, no. 1 (February 2022): 69–76. http://dx.doi.org/10.1063/1674-0068/cjcp2111223.

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The symmetric and quadrupolar donor-acceptor-donor (D-A-D) molecules usually exhibit excited-state charge redistribution process from delocalized intramolecular charge transfer (ICT) state to localized ICT state. Direct observation of such charge redistribution process in real-time has been intensively studied via various ultrafast time-resolved spectroscopies. Femtosecond stimulated Raman spectroscopy (FSRS) is one of the powerful methods which can be used to determine the excited state dynamics by tracking vibrational mode evolution of the specific chemical bonds within molecules. Herein, a molecule, 4,4′-(buta-1,3-diyne-1,4-diyl)bis( N, N-bis(4-methoxyphenyl)aniline), that consists of two central adjacent alkyne (-C≡C-) groups as electron-acceptors and two separated, symmetric N, N-bis(4-methoxyphenyl)aniline at both branches as electron-donors, is chosen to investigate the excited-state photophysical properties. It is shown that the solvation induced excited-state charge redistribution in polar solvents can be probed by using femtosecond stimulated Raman spectroscopy. The results provide a fundamental understanding of photoexcitation induced charge delocalization/localization properties of the symmetric quadrupolar molecules with adjacent vibrational markers located at central position.

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36

Konovalova, V. S., R. S. Konovalov, and S. I. Konovalov. "STUDY OF PULSE MODE OF PIEZOELECTRIC TRANSDUCER FOR ECHOSCOPE." Issues of radio electronics, no. 2 (February 20, 2019): 50–57. http://dx.doi.org/10.21778/2218-5453-2019-2-50-57.

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The piezoelectric transducer of the echoscope intended for research of soft tissues of the person is considered. The active element of the transducer is a damped piezoceramic plate. As an exciting electric signal, an electric voltage pulse with a different number of half‑cycles at the natural frequency of the plate is selected. The pulse mode of the radiator operation is investigated. The amplitudes and durations of the probing acoustic signal are estimated depending on the duration of the exciting pulse. The dynamics of changes in the durations and amplitudes of the radiated acoustic pulses is studied. For various degrees of damping of the plate, the number of half‑cycles contained in the exciting signal, from which the emitter operates in a stationary mode, is determined. The obtained results can be used in the field of design and development of technology for manufacturing of broadband pulse piezoelectric transducers of ultrasonic medical echoscopes.

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37

Quan, Li Na, Yoonjae Park, Peijun Guo, Mengyu Gao, Jianbo Jin, Jianmei Huang, Jason K. Copper, et al. "Vibrational relaxation dynamics in layered perovskite quantum wells." Proceedings of the National Academy of Sciences 118, no. 25 (June 15, 2021): e2104425118. http://dx.doi.org/10.1073/pnas.2104425118.

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Organic–inorganic layered perovskites, or Ruddlesden–Popper perovskites, are two-dimensional quantum wells with layers of lead-halide octahedra stacked between organic ligand barriers. The combination of their dielectric confinement and ionic sublattice results in excitonic excitations with substantial binding energies that are strongly coupled to the surrounding soft, polar lattice. However, the ligand environment in layered perovskites can significantly alter their optical properties due to the complex dynamic disorder of the soft perovskite lattice. Here, we infer dynamic disorder through phonon dephasing lifetimes initiated by resonant impulsive stimulated Raman photoexcitation followed by transient absorption probing for a variety of ligand substitutions. We demonstrate that vibrational relaxation in layered perovskite formed from flexible alkyl-amines as organic barriers is fast and relatively independent of the lattice temperature. Relaxation in layered perovskites spaced by aromatic amines is slower, although still fast relative to bulk inorganic lead bromide lattices, with a rate that is temperature dependent. Using molecular dynamics simulations, we explain the fast rates of relaxation by quantifying the large anharmonic coupling of the optical modes with the ligand layers and rationalize the temperature independence due to their amorphous packing. This work provides a molecular and time-domain depiction of the relaxation of nascent optical excitations and opens opportunities to understand how they couple to the complex layered perovskite lattice, elucidating design principles for optoelectronic devices.

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38

Dhamija, Shaina, Bhisham Thakur, Purnananda Guptasarma, and Arijit K. De. "Probing the excited state dynamics of Venus: origin of dual-emission in fluorescent proteins." Faraday Discussions 207 (2018): 39–54. http://dx.doi.org/10.1039/c7fd00187h.

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39

Kersting, R., B. Mollay, M. Rusch, J. Wenisch, G. Leising, and H. F. Kauffmann. "Femtosecond site-selective probing of energy relaxing excitons in poly(phenylenevinylene): Luminescence dynamics and lifetime spectra." Journal of Chemical Physics 106, no. 7 (February 15, 1997): 2850–64. http://dx.doi.org/10.1063/1.473094.

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40

Link, Andreas, and Thomas Franke. "Acoustic erythrocytometer for mechanical cell probing." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A36. http://dx.doi.org/10.1121/10.0015456.

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The mechanical properties of cells provide key insights into the type, differentiation and/or pathology of a cell. The mechanical analysis of a cell population, such as a blood sample, enables meaningful biological and medical interpretation for the diagnosis and monitoring of diseases. There are number of diseases, which alter the mechanical properties of human red blood cells (RBCs). Here, an acoustic method to probe both the viscous and elastic mechanics of single RBCs by SAW in a microfluidic device is presented. The device operates by exciting a surface acoustic wave in a microfluidic channel creating a stationary acoustic wave field of nodes and antinodes. RBCs are attracted to the nodes and are deformed. Using a stepwise increasing and periodically oscillating acoustic field, the static and dynamic deformation of individual red blood cells one by one was studied and the deformation by the Taylor deformation index D and relaxation times were quantified. The precision of the measurement allows to distinguish between individual cells in the suspension and provides a quantitative viscoelastic fingerprint of the blood sample with a resolution of a single cell. The method overcomes limitations of other techniques that provide averaged values and has the potential for high-throughput screening.

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41

Raj, Sumana, Shane Devlin, Riccardo Mincigrucci, Craig Schwartz, Emiliano Principi, Filippo Bencivenga, Laura Foglia, et al. "Free Electron Laser Measurement of Liquid Carbon Reflectivity in the Extreme Ultraviolet." Photonics 7, no. 2 (May 23, 2020): 35. http://dx.doi.org/10.3390/photonics7020035.

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Ultrafast time-resolved extreme ultraviolet (EUV) reflectivity measurements of optically pumped amorphous carbon (a-C) have been performed with the FERMI free electron laser (FEL). This work extends the energy range used in previous reflectivity studies and adds polarization dependence. The EUV probe is known to be sensitive to lattice dynamics, since in this range the reflectivity is essentially unaffected by the photo-excited surface plasma. The exploitation of both s- and p-polarized EUV radiation permits variation of the penetration depth of the probe; a significant increase in the characteristic time is observed upon increasing the probing depth (1 vs. 5 ps) due to hydrodynamic expansion and consequent destruction of the excited region, implying that there is only a short window during which the probed region is in the isochoric regime. A weak wavelength dependence of the reflectivity is found, consistent with previous measurements and implying a maximum electronic temperature of 0.8 eV ± 0.4.

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42

Zatsikha, Yuriy V., Liliya I. Shamova, Jacob W. Schaffner, Andrew T. Healy, Tanner S. Blesener, Gabriel Cohen, Brandon Wozniak, David A. Blank, and Victor N. Nemykin. "Probing Electronic Communication and Excited-State Dynamics in the Unprecedented Ferrocene-Containing Zinc MB-DIPY." ACS Omega 5, no. 44 (October 27, 2020): 28656–62. http://dx.doi.org/10.1021/acsomega.0c03764.

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43

Batat, Pinar, Martine Cantuel, Gediminas Jonusauskas, Luca Scarpantonio, Aniello Palma, Donal F. O’Shea, and Nathan D. McClenaghan. "BF2-Azadipyrromethenes: Probing the Excited-State Dynamics of a NIR Fluorophore and Photodynamic Therapy Agent." Journal of Physical Chemistry A 115, no. 48 (December 8, 2011): 14034–39. http://dx.doi.org/10.1021/jp2077775.

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44

Alnaser, A. S., I. Bocharova, K. P. Singh, C. Wei, M. Kling, C. L. Cocke, and I. V. Litvinyuk. "Probing excited states dynamics in CO cations using few-cycle IR and EUV laser pulses." Journal of Physics: Conference Series 194, no. 3 (November 1, 2009): 032046. http://dx.doi.org/10.1088/1742-6596/194/3/032046.

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45

Hennes, Marcel, Benedikt Rösner, Valentin Chardonnet, Gheorghe S. Chiuzbaian, Renaud Delaunay, Florian Döring, Vitaliy A. Guzenko, et al. "Time-Resolved XUV Absorption Spectroscopy and Magnetic Circular Dichroism at the Ni M2,3-Edges." Applied Sciences 11, no. 1 (December 31, 2020): 325. http://dx.doi.org/10.3390/app11010325.

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Ultrashort optical pulses can trigger a variety of non-equilibrium processes in magnetic thin films affecting electrons and spins on femtosecond timescales. In order to probe the charge and magnetic degrees of freedom simultaneously, we developed an X-ray streaking technique that has the advantage of providing a jitter-free picture of absorption cross-section changes. In this paper, we present an experiment based on this approach, which we performed using five photon probing energies at the Ni M2,3-edges. This allowed us to retrieve the absorption and magnetic circular dichroism time traces, yielding detailed information on transient modifications of electron and spin populations close to the Fermi level. Our findings suggest that the observed absorption and magnetic circular dichroism dynamics both depend on the extreme ultraviolet (XUV) probing wavelength, and can be described, at least qualitatively, by assuming ultrafast energy shifts of the electronic and magnetic elemental absorption resonances, as reported in recent work. However, our analysis also hints at more complex changes, highlighting the need for further experimental and theoretical studies in order to gain a thorough understanding of the interplay of electronic and spin degrees of freedom in optically excited magnetic thin films.

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46

Milne, Chris, Jakub Szlachetko, Tom Penfold, Majed Chergui, and Rafael Abela. "Preparing for SwissFEL: Exploring the limits of time-resolved X-ray spectroscopy." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C129. http://dx.doi.org/10.1107/s2053273314098702.

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Using x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) to probe laser-excited samples we can obtain excited-state structural and electronic dynamical information not available through other techniques.[1] One of the restrictions of most synchrotron-based implementations of this technique is the three-orders of magnitude mismatch between x-ray and laser repetition rates (MHz Vs. kHz). By using a laser capable of generating significant pulse energies at MHz repetition rates we can eliminate this discrepancy, thus greatly reducing measurement times and enhancing achievable signal-to-noise ratios.[2] Several examples that demonstrate the strength of this technique will be presented, including probing the electron relaxation in photoexcited TiO2 nanoparticles in solution and resolving the dynamical structural changes associated with ligand rebinding in the protein myoglobin under physiological conditions. The ability to extend these types of measurements into the femtosecond regime at Experimental Station A[3] at the SwissFEL hard X-ray free electron laser, which is under construction at the Paul Scherrer Institute (Villigen, Switzerland), will be discussed.

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47

Kim, Myung Hwa, Wen Li, Suk Kyoung Lee, and Arthur G. Suits. "Probing of the hot-band excitations in the photodissociation of OCS at 288 nm by DC slice imaging." Canadian Journal of Chemistry 82, no. 6 (June 1, 2004): 880–84. http://dx.doi.org/10.1139/v04-072.

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The photodissociation dynamics of OCS at 288 nm has been investigated using the DC (direct current) slice imaging technique, which is a recently developed high-resolution "slicing" approach that directly measures the central slice of the photofragment distribution in imaging experiments. By analyzing a DC sliced image of S(1D2) photofragments we observe dissociation originating from OCS molecules excited up to v2 = 4 in the molecular beam. The measured translational energy distribution was used to determine the branching ratio for the contribution from each initial bending state (0 v2 0) of OCS and relative photodissociation cross section ratios compared to v2 = 1. Large negative anisotropy parameters determined as a function of the S(1D2) fragment recoil speed indicate that the photodissociation of OCS at 288 nm occurs exclusively from the 11A′′(1Σ) bending excited potential surface that can be accessed through a perpendicular transition.Key words: DC slicing imaging, OCS, photodissociation, hot-band excitation.

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48

Matsumoto, Kosei, Takao Nakagawa, Keiichi Wada, Shunsuke Baba, Shusuke Onishi, Taisei Uzuo, Naoki Isobe, and Yuki Kudoh. "Probing Dynamics and Thermal Properties Inside Molecular Tori with CO Rovibrational Absorption Lines." Astrophysical Journal 934, no. 1 (July 1, 2022): 25. http://dx.doi.org/10.3847/1538-4357/ac755f.

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Abstract A recent hydrodynamic model, the radiation-driven fountain model (Wada et al. 2016), presented a dynamical picture that active galactic nuclei (AGNs) tori sustain their geometrical thickness by gas circulation around AGNs, and previous papers have confirmed that this picture is consistent with multiwavelength observations of nearby Seyfert galaxies. Recent near-infrared observations implied that CO rovibrational absorption lines (ΔJ = ± 1, v = 0 − 1, λ ∼ 4.7 μm) could probe the physical properties of the inside tori. However, the origin of the CO absorption lines has been under debate. In this paper, we investigate the origin of the absorption lines and conditions for detecting them by performing line radiative transfer calculations based on the radiation-driven fountain model. We find that CO rovibrational absorption lines are detected at inclination angles θ obs = 50°–80°. At the inclination angle θ obs = 77°, we observe multi-velocity components: inflow (v LOS = 30 km s−1), systemic (v LOS = 0 km s−1), and outflows (v LOS = −75, − 95, and −105 km s−1). The inflow and outflow components (v LOS = 30 and −95 km s−1) are collisionally excited at the excitation temperatures of 186 and 380 K up to J = 12 and 4, respectively. The inflow and outflow components originate from the accreting gas on the equatorial plane at 1.5 pc from the AGN center and the outflowing gas driven by AGN radiation pressure at 1.0 pc, respectively. These results suggest that CO rovibrational absorption lines can provide us with the velocities and kinetic temperatures of the inflow and outflow in the inner few parsec region of AGN tori, and the observations can probe the gas circulation inside the tori.

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Zamponi, Flavio, Thomas J. Penfold, Maarten Nachtegaal, Andrea Lübcke, Jochen Rittmann, Chris J. Milne, Majed Chergui, and Jeroen A. van Bokhoven. "Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy." Phys. Chem. Chem. Phys. 16, no. 42 (2014): 23157–63. http://dx.doi.org/10.1039/c4cp03301a.

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50

Schmidtke, Sarah J., David F. Underwood, and David A. Blank. "Probing Excited-State Dynamics and Intramolecular Proton Transfer in 1-Acylaminoanthraquinones via the Intermolecular Solvent Response." Journal of Physical Chemistry A 109, no. 32 (August 2005): 7033–45. http://dx.doi.org/10.1021/jp051964l.

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