scholarly journals Tunneling Calculation in the Field Ion Microscope

2020 ◽  
Vol 12 ◽  
pp. 5-10
Author(s):  
Ariel Almeida Abreu Silva ◽  
A.V. Andrade-Neto
Keyword(s):  
Rate Constants ◽  
Ionization Probability ◽  
Ionization Rate ◽  
Model Potential ◽  
Inert Gas ◽  
Dimensional Model ◽  
Ionization Zone ◽  
One Dimensional ◽  
Barrier Penetration ◽  
Field Ion Microscope

In this work we describe calculations of tunneling rate constants for the Field Ion Microscope (FIM) using one-dimensional model potential that simulates the ionization process in a FIM. We obtain expressions for the ionization rate constant (ionization probability per unit of time) of inert gas atoms as a function of their position above the surface. In order to calculate the probability of barrier penetration we have used the semiclassical (JWKB) approximation. We have also calculated ionization zone widths as the distance between points where ionization rate is a maximum and half of this value. An application to helium as the imaging gas is presented to highlight the power of the method.

scholarly journals Photoemission time versus streaking delay in attosecond time-resolved solid state photo-emission

2019 ◽  
Vol 205 ◽  
pp. 02019
Author(s):  
Andreas Gebauer ◽  
Sergej Neb ◽  
Walter Enns ◽  
Ulrich Heinzmann ◽  
Andrey K. Kazansky ◽  
...  
Keyword(s):  
Solid State ◽  
Schrödinger Equation ◽  
Schrodinger Equation ◽  
Model Potential ◽  
Time Dependent ◽  
Dimensional Model ◽  
Time Resolved ◽  
One Dimensional

Time-dependent Schrodinger equation simulations for a one-dimensional model potential reveal that the delay extracted from a streaking spectrogram does not reflect the photoemission time if the streaking field inside the solid cannot be neglected.

scholarly journals Pulsation – convection interaction

2013 ◽  
Vol 9 (S301) ◽  
pp. 177-184
Author(s):  
F. Kupka ◽  
E. Mundprecht ◽  
H. J. Muthsam
Keyword(s):  
Numerical Simulations ◽  
Large Scale ◽  
Dimensional Model ◽  
Instability Strip ◽  
Ionization Zone ◽  
One Dimensional ◽  
Short Period ◽  
Problematic Issue ◽  
Long Time ◽  
Hydrodynamical Simulations

AbstractA lot of effort has been devoted to the hydrodynamical modelling of Cepheids in one dimension. While the recovery of the most basic properties such as the pulsational instability itself has been achieved already a long time ago, properties such as the observed double-mode pulsation of some objects and the red-edge of the classical instability strip and their dependence on metallicity have remained a delicate issue. The uncertainty introduced by adjustable parameters and further physical approximations introduced in one-dimensional model equations motivate an investigation based on numerical simulations which use the full hydrodynamical equations. In this talk, results from such two-dimensional numerical simulations of a short period Cepheid are presented. The importance of a carefully designed numerical setup, in particular of sufficient resolution and domain extent, is discussed. The problematic issue of how to reliably choose fixed parameters for the one-dimensional model is illustrated. Results from an analysis of the interaction of pulsation with convection are shown concerning the large-scale structure of the He ii ionization zone. We also address the influence of convection on the atmospheric structure. Considering the potential of hydrodynamical simulations and the wealth of ever improving observational data an outlook on possible future work in this field of research is given.

IONIZATION AND STABILIZATION OF A ONE-DIMENSIONAL MODEL ATOM: MAP APPROACH

1999 ◽  
Vol 13 (12) ◽  
pp. 1489-1502 ◽  
Author(s):  
TAIWANG CHENG ◽  
JIE LIU ◽  
SHIGANG CHEN
Keyword(s):  
Phase Space ◽  
Wigner Distribution ◽  
Ionization Rate ◽  
Intense Laser ◽  
Ionization Process ◽  
Space Region ◽  
Dimensional Model ◽  
One Dimensional ◽  
Quantum Version ◽  
Model Atom

In this paper, the interactions between a one-dimensional model atom and intense laser field is approximately described by a map. Both the classical version and quantum version of this map are studied. It is shown that besides classical stable islands which can bound some phase space region against ionization and then are responsible for the atomic stabilization, there is another structure in phase space, the unstable manifold, which can determine the ionization process of the system. Quantumly, the quantum quasienergy eigenstates (QE state) under absorptive boundaries, which directly related to the ionization process, are calculated. We define the QE state with smallest ionization rate as QE0 state, which represents the stabilization degree. The Wigner distribution of such QE0 state show clear fringe structures. Finally we show that the classical description and quantum description are in a correspondence manner.

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