arXiv subjects

Chuanlu Yang

Publications and source records attributed to Chuanlu Yang.

5 recordsLinked to original sources

arXiv2026

Light-Driven Ferroic Switching Enables Reversible Control of Hydrogen Adsorption Thermodynamics

Reversible ultrafast switching of surface thermodynamics is highly desirable for hydrogen storage and catalysis yet remains elusive at the nanoscale. Here we demonstrate that photoinduced ferroic-order switching in two-dimensional ionic ferroelectric monolayers enables rapid, reversible control of hydrogen binding. In TiGeSe$_3$, carrier-density-driven redistribution of transition-metal 3\textit{d} orbital occupations triggers a sequential evolution from the ferroelectric ground state to paraelectric phases with staggered or Zig-Zag antiferromagnetic order. This switch continuously tunes the hydrogen adsorption free energy from 0.33 to 1.11 eV, shifting the interface from near-thermoneutrality to spontaneous desorption. Nonadiabatic dynamics indicate that electron-phonon coupling promotes nonthermal H release, while picosecond carrier recombination rapidly restores the initial ferroic order, closing an ultrafast reversible cycle. Generality is further validated in AgBiP$_2$Se$_6$ and CuInP$_2$S$_6$, establishing ferroic order as an optically addressable knob for dynamic thermodynamic reconfiguration beyond static design.

cond-mat.mtrl-sci↗

arXiv2020

Average Doppler Shift of Gamma-ray Spectra of Positron Annihilation Process in Molecules

This paper studies the gamma-ray spectra of positron annihilation processes in a series of molecules. The results show that the average valence electron energy of the molecules has a linear correlation with the full width at half maximum (FWHM) of the gamma-ray spectra. In addition, we defined a new physical quantity Average Doppler Shift (ADS), which can be used as the eigenvalue to describe the characteristics of the gamma-ray spectra. Since ADS contains all the information about the gamma-ray spectra, it can more accurately represent the characteristics of the gamma-ray spectra. For a series of molecules, this paper compares the ADS and FWHM of their gamma-ray spectra and the average valence electron energy. The results show that ADS has a linear correlation with the average valence electron energy and the FWHM. Further, this proves that the annihilation mainly occurs on valence electrons, and it also illustrates that the ADS has certain applicability. It is expected that this will provide us with a deeper understanding of the positron annihilation process.

physics.atm-clus↗

arXiv2020

An alternative indicator of annihilated electrons in atoms: Rahm's electronegativity scale

This paper presents a new explanation of the width of gamma-ray spectra based on Rahm's electronegativity scale. This quantitatively proves, for the first time, that positrophilic electrons in the positron-electron annihilation process are exactly the valence electrons. This suggests the replacement of Full Width at Half Maximum (FWHM) of the gamma-ray spectra with the newly defined physical quantity Average Doppler Shift (ADS). Both FWHM and ADS of the gamma-ray spectra in light elements agree well with the corresponding Rahm's electronegativity values, respectively. Further, ADS provides strong evidence in favor of Rahm's electronegativity scale. It is expected that this will be useful in understanding the mechanism of the positron-electron annihilation process.

physics.atm-clus↗

arXiv2020

Gamma -ray spectra in the positron-annihilation process of molecules at room temperature

In this study, a fully self-consistent method was developed to obtain the wave functions of the positron and electrons in molecules simultaneously. The wave function of a positron at room temperature , with a characteristic energy of approximately $0.04 eV$, was used to analyse the experimental results of its annihilation in helium, neon, hydrogen, and methane molecules. The interactions between the positron and molecule provide a significant correction in the gamma-ray spectra of the annihilating electron--positron pairs. It was also observed that high-order correlations offered almost no correction in the spectra, as the interaction between the low-energy positron and electrons cannot drive the electrons into excited electronic states. More accurate studies, which consider the coupling of the positron--electron pair states and vibration states of nuclei, must be undertaken.

physics.atm-clus↗

arXiv2014

Probing the Conformations of Single Molecule via Photon Counting Statistics

We suggest an approach to detect the conformation of single molecule by using the photon counting statistics. The generalized Smoluchoswki equation is employed to describe the dynamical process of conformational change of single molecule. The resonant trajectories of the emission photon numbers $ $ and the Mandel's $Q$ parameter, in the space of conformational coordinates $\bm{\mathcal{X}}$ and frequency $ω_L$ of external field ($\bm{\mathcal{X}}-ω_L$ space), can be used to rebuild the conformation of the single molecule. As an example, we consider Thioflavin T molecule. It demonstrates that the results of conformations extracted by employing the photon counting statistics is excellent agreement with the results of {\it ab initio} computation.

physics.chem-ph↗