Spectroscopy of correlated electron pairs was employed to investigate the energy dissipation process, as well as the transport and the emission of low-energy electrons on a polymethylmethacrylate surface, providing secondary electron spectra causally related to the energy loss of the primary. Two groups are identified in the cascade of slow electrons, corresponding to different stages in the energy dissipation process. The characteristic lengths for attenuation due to collective excitations and momentum relaxation are quantified for both groups and are found to be distinctly different: λ_{1}=(12±2) Å and λ_{2}=(62±11) Å. The results strongly contradict the commonly employed model of exponential attenuation with the electron inelastic mean free path as characteristic length, but they essentially agree with a theory used for decades in astrophysics and neutron transport, albeit with characteristic lengths expressed in units of angstroms rather than light-years.
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http://dx.doi.org/10.1103/PhysRevLett.132.186203 | DOI Listing |
Recently, the dissipative soliton (DS) generation in the positive fourth-order-dispersion (FOD) fiber laser has been theoretically predicted, namely dissipative pure-quartic soliton (DPQS), featuring a higher energy-scaling ability compared to conventional DS dominated by positive group velocity dispersion. Here, we discover that the formation of spectral sidebands is always accompanying by the stabilized DPQS in the fiber laser, which is different from the conventional DS. Due to the combination of positive FOD and self-phase modulation, low- and high-frequency components are distributed at the leading and trailing edges of the pulse, forming the pedestals that propagate with it.
View Article and Find Full Text PDFSci Rep
January 2025
School of Mechanical and Engineering, Liaoning Technical University, Fuxin, 123000, China.
As the depth of coal mining in China continues to increase, the fracturing of coal rock masses has an increasingly complex impact on the surrounding rock roadways. The majority of the mine's roadways run through coal rock masses with hard roofs and soft bottoms, which typically exhibit complex dynamic behaviour. To further research the mechanical behaviour and fracture evolution of coal rock masses under hard-roof and soft-floor conditions, the study is based on the majority of working faces in a mine, which have hard roofs and soft floors.
View Article and Find Full Text PDFPlant Physiol Biochem
January 2025
Plant Sciences and Agrotechnology Division, Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu, J & K, 180001, India; Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh, 201002, India. Electronic address:
Transplantation experiments conducted in high altitude ecosystems are rising as key strategy to examine the response of individual plant transplanted across distinct elevations. However, plant physiological and biochemical performance in response to changes in abiotic factors across different species and mountain ranges is still lacking. So in the present study, we have made an attempt to link the physiological performance with that of altitudinal gradient in Ladakh by transplanting Lepidium latifolium at four different altitudinal sites.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Science Institute and Faculty of Physical Sciences, University of Iceland, Reykjavík, Iceland.
Understanding the ultrafast vibrational relaxation following photoexcitation of molecules in a condensed phase is essential to predict the outcome and improve the efficiency of photoinduced molecular processes. Here, the vibrational decoherence and energy relaxation of a binuclear complex, [Pt2(P2O5H2)4]4- (PtPOP), upon electronic excitation in liquid water and acetonitrile are investigated through direct adiabatic dynamics simulations. A quantum mechanics/molecular mechanics (QM/MM) scheme is used where the excited state of the complex is modeled with orbital-optimized density functional calculations while solvent molecules are described using potential energy functions.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany.
Nonadiabatic coupling between electrons and molecular motion at metal surfaces leads to energy dissipation and dynamic steering effects during chemical surface dynamics. We present a theoretical approach to the scattering of molecules from metal surfaces that incorporates all nonadiabatic and quantum nuclear effects due to the coupling of the molecular degrees of freedom to the electrons in the metal. This is achieved with the hierarchical equations of motion (HEOM) approach, combined with a matrix product state representation in twin space.
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