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  • 26 votes cast
Oct
27
comment In the double slit experiment with electrons why the single slit case is not diffracting as photons would have?
Thank you. Is the fringe visibility 100% as illustrated on the picture ?
Oct
27
comment How do chirped mirrors compensate dispersion?
They would optimize the layer thicknesses so that it matches their desired dispersion.
Oct
27
comment How can I get the energy levels from a Hamiltonian?
I assume the program has calculated using some basis set the energy levels modified by the magnetic field. The eigenvectors are the states with the coresponding eigenvalues or energies.
Oct
27
comment In the double slit experiment with electrons why the single slit case is not diffracting as photons would have?
Ok It is designed to be that way. Thanks.
Oct
27
comment Which waveguide mode will be excited by circularly polarized laser mode $\mathrm{TEM}_{00}$ entering hollow fiber?
Thank you. If the incoming beam with circular polarization excites the fundamental HE11 mode, How is the circular polarization preserved. HE11 has almost linear polarization.
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.
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 ?
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
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
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.
Nov
11
comment What spin-statistics is a magnetic monopole expected to obey?
No. But short answer will be best :)
Oct
27
comment What limits laser pulse duration to single cycle?
Thanks. But why is the one cycle the limit. What would be wrong with half cycle ? Is it bandwidth problem or propagation that sets the limit ?
Oct
15
comment Photoelectric effect high frequency limit?
I guess the work function will also change increasing the energy. Might be wrong but at high energy only the core electrons will have high enough cross section to interact with the photons. The question is if the binding energy of the most tightly bound electron is 1000eV let say, would a photon do anything to the material if it has significantly higher energy and do not interact anymore?
Oct
15
comment Max temperature that can be obtained from radiation source when nonlinear interaction with matter is important?
There are many issues, but the question is about the temperature limit and the entropy.
Oct
14
comment Max temperature that can be obtained from radiation source when nonlinear interaction with matter is important?
Here the re-radiation will come from electrons returning to their ions and radiation is at 24eV and 54eV lets say for simplicity. It looks hotter somehow to me.
Oct
14
comment Max temperature that can be obtained from radiation source when nonlinear interaction with matter is important?
Sun was an example, the heating is through radiation away from the source.
Oct
14
comment Max temperature that can be obtained from radiation source when nonlinear interaction with matter is important?
Not related to the question. Any wavelength is ionizing radiation provided it can have the peak intensity to overcome the binding potential of the electron.
Oct
8
comment Two balls falling one above the other
hep.physics.wayne.edu/~harr/courses/5200/f07/lecture24.htm here is your solution