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 Oct 12 asked How is the temporal coherence of a pulse defined? Oct 6 comment How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis Thank you. Ex(x,t)=exp(−t2/τ2−iω0t)) is happily propagating in the FDTD method. I would like to understand the FDTD better, what are the update equations and how many dimensions I need to propagate Ex(x,t)=exp(−t2/τ2−iω0t)exp(−x2/w2o) . And how is the source field inserted. The term k.z might be needed. Basically a procedure. Oct 6 comment How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis Thank you it is a good book, but I can not find that example discussed there. Oct 6 comment How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis Thank you. I would like to understand the FDTD a bit better, what are the update equations and how many dimensions I need to propagate Ex(x,t)=exp(−t2/τ2−iω0t)exp(−x2/w2o) . And how is the source field inserted. I am sure there programs can do it. Oct 2 revised How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis edited title Oct 2 revised How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis added 40 characters in body Oct 2 revised How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis added 40 characters in body Oct 1 revised How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis added 11 characters in body; edited title Sep 28 asked How to propagate $E_x (x,t) = \exp(-t^2/\tau^2-i\omega_0 t) \exp(-x^2/w_0^2)$ in finite difference time domain (FDTD) analysis Jul 2 comment How are determined experimentally the energy levels of the atoms ? How is the calibration done to several decimal points? Thank you. I get that a spectrometer could have high resolution. But I guess I am trying to understand how is absolute energy associated with particular absorption line ? Why is some edge at 284 not 280eV and why different people think some edges (absorption lines) are at slightly different energies ? Jul 1 revised How are determined experimentally the energy levels of the atoms ? How is the calibration done to several decimal points? added 78 characters in body Jul 1 asked How are determined experimentally the energy levels of the atoms ? How is the calibration done to several decimal points? Apr 28 awarded Popular Question Apr 22 accepted What is the reason that EXAFS are done with monochromatic x-ray light? Apr 21 comment What is the reason that EXAFS are done with monochromatic x-ray light? Thanks. My question is which process in the exafs fails if the beam is not monochromatic. Where is the TEY (total electron yield) used, is it in analysis. Arent photons that are collected? Apr 21 revised What is the reason that EXAFS are done with monochromatic x-ray light? added 14 characters in body Apr 21 comment Resolving power of a diffraction grating? This is the condition for multiple N slit principle max nλ=dsin(θ). The min occur at sλ=Ndsin(θ) s = +/-1,2, when s/N is integer it is principle max. There are N-2 max between each principal max and N-1 min. As the N is increased the width of the principle max decreases so the spectral resolution increase. Apr 21 revised What is the reason that EXAFS are done with monochromatic x-ray light? added 28 characters in body Apr 21 asked What is the reason that EXAFS are done with monochromatic x-ray light? Apr 21 comment Does the EXAFS oscillations occur when ultrashort x-ray pulse is used? Electron with a 50eV kinetic energy will travel in 0.1fs 4.2 Angstroms Thank you. I guess that my next question is the spectrum of the x-ray required to be monochromatic. I basically dont understand the electron wave interference picture and the nature of the EXAFS oscillation and ask what if blindly. What I am trying to understand is does the electron has to return to the absorbing atom, to modify the absorption, and what if the auger decay happens before the electron returns. Is timing anyhow limiting anything.