Recent content by eneacasucci

thank you so much for your time. The example was clear, but in a Fabry–Perot interferometer (also called an étalon) we change the lenght of the "trasmission line" that is the distance of the two mirros, right? We change it firstly macroscopically and then microscopically with a piezo. We see...

What I find hard to visualise is the fact that in the spectrum there are different Rayleigh peaks but they represent the same laser source but at different orders since d varies, and I cannot visualise what actually the FSR range is. The distance between the peaks is lambda/2 but why does it...

Thanks for the answer. The distinction of holding different parameters fixed is clear to me now. However, I am still confused about why, in a Brillouin experiment where we mechanically scan the cavity (varying ##d##), the Free Spectral Range (FSR) is defined using the formula derived for a fixed...

I am analyzing data from a Brillouin spectroscopy experiment using a scanning Fabry-Pérot Interferometer (FPI). The source is a monochromatic laser with a fixed wavelength ##\lambda##. I have a conceptual question regarding the relationship between the mechanical piezo scan and the Free...

I was referring to the collective lattice displacement field (the deviation of atoms from equilibrium).The reason I phrased it as 'the normal mode is the wave' is that in a periodic crystal structure, the normal modes of vibration take the form of traveling plane waves (characterized by...

Indeed, in Kittel's discussion of phonons, it states: "A phonon of wavevector ##\mathbf{k}## will interact with particles such as photons, neutrons, and electrons as if it had a momentum ##\hbar\mathbf{k}##. However, a phonon does not carry physical momentum." Is it correct what I'm writing in...

I am currently reading Kittel's Introduction to Solid State Physics and am confused by the terminology regarding phonons. On page 99 (8th ed.), regarding Eq. 27, Kittel writes: "The energy of an elastic mode of angular frequency ## \omega ## is ## \epsilon = (n + 1/2)\hbar\omega ## when the...

This explanation is super informative and accurate, I cannot thank you enough for this. My notes were wrong and I was so confused about it.

I've found this image online (ref: https://edurev.in/t/188018/Origin-of-Energy-Bands ), it should be the graphical representation of the potential binding energy between two nearest-neighbor atoms. I don't understand how it can be correlated to the Lennard-Jones pontential graph: , in which we...

I found this image on the wikipedia italian page for the Lennard-Jones potential and I think the derivative displayed are wrong: not only in that reange (below r_eq) the negative derivative of the force should be negative and vice versa, but also the physcal meaning is that F(r) = -...

thank you so much, that is exactly what i was asking

##2\pi \int_{-1}^1 d\mu' = 4\pi## we can't write this, in our case because we have a function ##\varphi## that depends on ##\mu## (or ##\theta##) so the only integral that we can directly solve is the one related to the azimuthal angle (that gives the ##2\pi##), because none of the functions...

Thank you so much! Could I ask you also about this mathematical part "the integral over Omega in spherical coordinates has a part that is shown with the polar angle theta and then there is another integral from 0 to 2\pi for the azimuthal angle. This last integral should have as an integrand 1...

I have a question about the neutron transport equation, my question is more about mathematics, from the book Duderstadt Hamilton I tried to make the calculations, it should be quite simple but still I don't understand where the 2\pi terms went... the integral over Omega in spherical...

So to make it discontinuous we should explicitly define a piecewise function like: f(x)=ln(x) for x>0 and f(x)=0 for x≤0? It is not enough to say "consider ln(x) over whole R" then, right?