Questions tagged [absorption]
A transition by which the energy of at least one photon is completely transferred to a material.
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Do vibrational frequencies produced from sound pass through your entire body? from one side to another? [closed]
when there is a noise by me, i feel the vibration on my skin from the direction it’s coming, it moves into my body. a wall of what sound would feel like passing through me. i perceive it as container ...
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What 3d shape does water form when dropped on paper?
Say you have a stack of paper and you gently drop water on it (anything from 1 to 10 drops). How will water transfer through the paper ? What shape will it form ? What mathematical function best ...
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Heating of a metallic 'gray body' by radiation
I am interested in a realistic model for calculating the heating of a metallic body by solar radiation.
Assumption (0) is vacuum, so neither conduction nor convection.
Assumption (1) is integration ...
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Optical matrix element in graphene: is electron $k$ perpendicular to $E$?
I faced some problems with understanding the process of light absorption in 2D (e.g. graphene). Suppose we have Dirac graphene hamiltonian, skipping all numerical factors:
$$ H = \hbar v\begin{pmatrix}...
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Absorption Spectra of Atmospheric Gases
From this previous Stackexchange question:
Is a detailed absorption spectrum available for carbon dioxide from 300-1100nm?
and this paper:
https://www.osti.gov/servlets/purl/1613653
as well as this ...
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Which linear region should be considered in a Tauc plot when two appear, the one closer to the origin, the one farther away, or both?
I am analyzing the band gap of $\rm TiO_2$ samples made by ALD and titanium anodization. My doubt is that in the samples made by titanium anodization, two linear regions appear in the Tauc plot, and I ...
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Why does light either get reflected, absorbed, or passes through a surface or obstacle?
For each of these 3 cases, I'm having trouble understanding...
If light is reflected, does that mean that there was not sufficient energy by the photons to excite the electrons of the surface to ...
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How does light interact with atoms?
I've read this answer regarding the difference between mere reflection and absorption followed by emission and I am struggling to understand some concepts. To begin with, we have some matter-light ...
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Why is mass loaded vinyl better at reducing sound transfer through walls than acoustic foam when they both absorb sound waves?
I have done research on mass-loaded vinyl (MLV), and it says it absorbs sound. I thought that acoustic foam was the only one of the two that absorbed sound, but apparently I am wrong. If the sources ...
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Why does sound absorbing foam stop echoes, but not transmission through the wall?
I understand echoes are sound reflections. But if foam absorbs sound, and if it reflects off the wall, then that means the waves travel through the foam, and if sound waves get transmitted from a ...
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What is the explanation that the same material could receives and reflects EM wave signal while another absorbs?
Here is B-2 Spirit, a stealth bomber by Northrop Grumman. Another one is a depiction of a parabolic dish antenna receiver. As we knew, the B-2 is a stealth aircraft, which is not reflects the received ...
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Ways Light Can Interact With Matter
Below you will see how my "understandings" and obsevations are in conflict. Please look them over and let me know what I am missing.
Absorption: Light can only be absorbed by an atom if it ...
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How to calculate the capability to heat a gas mixture via light emission that only some of the gas can absorb?
Consider a tank of gas with volume $v$ that's a mixture of gas $A$ (e.g. helium) along with some fraction $x$ of gas $B$ (e.g. nitrogen), at pressure $P$. For the purposes of the example assume $x \ll ...
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Absorption and Emission Spectra of Quantum Dots
For one of my next labs, I will be measuring the absorbtion and emission spectra of a tolulene solution with quantum dots in it. The gist of the idea is that I will end up obtaining a graph similar to ...
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How to calculate absorption coefficient from general solutions of Maxwell equations?
Consider a simple ridge structure with field variation only across one dimension, the general Maxwell equations read:
$\frac{\partial H}{\partial t}=\frac{1}{\mu} \frac{\partial E}{\partial z}$
$\frac{...
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Does colour of light depend on intensity of light? [closed]
By intensity I mean frequency of light
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Density of final states in photon absorption/emission by a hydrogen atom
Consider a hydrogen atom in an electromagnetic field. The Hamiltonian is of the form
$$\hat{H}=\underbrace{\frac{\hat{p}^2}{2m}+V(r)}_{\text{atom}}+\underbrace{\sum_{\vec{k},\sigma}\hbar cka^{\dagger}...
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Rabi oscillations with circularly polarized light
I am curious about what Rabi oscillations would look like if the external field was circularly, rather than linearly, polarized. I have been trying to work out the math on my own, but find it somewhat ...
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Coherent unpolarized laser light
I notice that in semiclassical treatments of laser light absorption by particles, they treat the laser beam as a coherent oscillating electric field over the form $E_0\cos(kx-\omega t)$, sometimes ...
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How does CT imaging deal with the thickness of materials?
In the medical CT imaging field, image of an inspected object is obtained through xray projection. xray is attenuated by the inspected object through the formula $I=I_0e^{-\mu t}$. The projection $p$ ...
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Why do we only look at transitions between energy-eigenstates, when perturbing a system with an oscillating interaction?
I have some doubts about the usual explanation of sharply peaked emission / absorption spectra, that one can observe when one looks at quantum mechanical systems, for example the hydrogen atom.
In ...
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Material that is one-sided translucent [closed]
Is there a polymer material that is translucent from one side but not from the other side?
I want to build some custom push buttons that should appear completely black. Only when they are led by an ...
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Decoherence via environmental photons
I am reading the book "Decoherence and the Quantum-to-Classical Transition" by Maximilian A. Schlosshauer, and I have come to understand that for a two-level system with eigenstates $|a\...
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Why do different metals glow with different colours if all solids have the same emission spectrum?
Why do different metals glow with different colors if all solids have the same emission spectrum? According to my teacher, all solids have the same emission spectrum at the same temperature due to ...
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If all matter can emit at all wavelengths, can all matter absorb at all wavelengths too?
Based on Planck’s law all matter can emit at all wavelengths at different intensities dependent of temperature. I was wondering if this holds true, does all matter absorb all wavelengths too, at ...
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Why is water a good neutron absorber?
I've seen this question asked multiple times, and the answer is never detailed. I initially assumed that either hydrogen or oxygen had relatively large neutron absorption cross sections, however that ...
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Why do we look at $X\rightarrow B$ transition in iodine?
In the classic experiment where one investigates the absorption profile of $I_2$ vapor, we look at $X\rightarrow B$ electronic transitions where $X$ denotes the ground state and $B$ the second excited ...
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Photon absorption in different layers
Let's suppose that space is divided into different regions:
for $x < 0$ there is just vacuum space;
for $x$ between 0 and $t_1$ space is filled with a material of type 1;
for $x$ between $t_1$ ...
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Absorption spectrum dependence on concentration/pressure
I am having difficulties understanding the relation between absorption spectrum and gas concentration. The online resources I found, including many questions here, do not clarify my doubts.
Take for ...
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What accounts for a Lyman-break for all wavelengths shorter than 91.2nm if the Lyman limit is the highest energy photon that Neutral hydrogen absorbs?
From this description of Lyman-break galaxies, I don't understand how:
...radiation at higher energies than the Lyman limit at 912 Å is almost completely absorbed by neutral gas around star-forming ...
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Why does an element show an absorption spectrum?
We know that the colour we see of different objects around us is because they absorb all the radiation except a specific wavelength which gets reflected back to us. So, in an emission spectrum, when ...
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Is a layer of gas with sufficiently large optical thickness really radiating as a black body?
Can a parcel of gas with large value of optical thickness really radiate like a black body?
I have in mind a simple (most likely oversimplified) model which yields
$$I_\nu = I_\nu(0) e^{-\tau\nu} + I_\...
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Can there be any doubt that atmospheric "backradiation" is absorbed at the surface?
I am deliberately asking this question in Physics rather than Earth Sciences because I think it does come down to specific physical processes.
The background is that I recently had a discussion where ...
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How is black body radiation from sample eliminated when measuring absorption coefficient?
I wonder how absorption spectra of a sample (e.g. gas with some $CO_2$ absorbing strongly at $\approx 15\mu m$) is measured by IR spectroscopy, thereby having in mind the following arrangement, ...
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What is the information needed from the low pressure cathode line profile in this experiment? Why the need to include it in the study?
Why do we need to create a spectral absorption profile for this experiment? What is it necesary to compare to the profile of the plasma?
Here is the paper link. https://iopscience.iop.org/article/10....
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Can anybody explain this Beer-Lambert's law condition for it to be valid?
"The incident radiation should preferably be monochromatic, or have at least a width that is narrower than that of the attenuating transition. Otherwise a spectrometer as detector for the power ...
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Why can Einstein coefficients be derived based on thermodynamically equilibrium relations when they are basically intrinsic?
Einstein coefficients for emission and absorption ($A_{21}$, $B_{12}$, $B_{21}$) are often derived from a consideration of thermodynamic equilibrium using Boltzmann statistics and comparison with ...
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Trouble with Einstein coefficients - what is the meaning of the transition probability?
Perhaps it seems to be a not very intelligent question, but I am unfortunately not able to understand what the probability per second that a molecule will absorb a photon is, as part of the theory of ...
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Correlation of the strength of the Balmer lines with the age of a galaxy
I don't understand why a strong absorption line H$\delta$ indicates a young star population.
First of all, a strong H$\delta$ line just means that I have more A-type stars, doesn't it? Where is the ...
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Identifing a formula for the contribution of IR scattering to the permittivity of metals
I'm using a software modelling the complex refractive index of different materials in the THz/far infrared frequency range. One of the parameters that the user can add to the model of the permittivity ...
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Deriving the absorption coefficient
Show that for a dilute medium and near resonance, the absorption coefficient is
$$\alpha(\omega)=\frac{Ne^2}{4m\epsilon_0c}\frac{\gamma}{(\omega_0-\omega)^2+(\gamma/2)^2}$$
From the Lorentz Oscillator ...
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What happens to the information that a photon carries, when it interacts with another body that reflects, transmits, or absorbs it?
When a photon gets absorbed in a body, it transfers all its information to the body(what we call "being absorbed"). Now, it is the body that further processes the information and releases it ...
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What is the energy difference between the 3d 4s valence subshells of iron (and copper)?
In gold, for example, the energy difference between the 5d 6s valence subshells is ≈ 2.7 eV (that's why it has color). But what about the 3d 4s subshells of iron and copper? What are their energy ...
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Photon absorption when angular momentum is not a good quantum number. On-shell condition
Suppose there is a spin 1 photon with angular momentum along z direction.
I understand an isolated hydrogen atom in s state can be excited to the p (+1 orbital angular momentum) state, while electron ...
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Need the (frequency dependent) dielectric permitivity of quartz
I have desperately googled to find a table or a graph for the complex dielectric permitivity of quartz (e.g. fused quartz), as a function of frequency, at room temperature. I am mostly interested in ...
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Converting light into heat/movement, reflection vs absorption
at school we had a small device in a glass dome it had 4 plates every plate was blackened on one side and silver colored on the other side. when the sun did shine on one side of it, it would start to ...
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Could the solar shield on the James Webb telescope have been pitch black or does it need to be highly reflective?
When I look at pictures of the sun shield on the James Webb Space telescope (JWST), I see something that looks highly reflective (and hence must have a very low emissivity). My intuition tells me that ...
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Pankove optical absorption equations: cgs problem?
I'm embarrassed to be asking this question here, but I've been beating my head against an equation for two weeks and can't get the numbers to work. I'm trying to plug in numbers into Jacque Pankove's &...
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Absorption & emission spectrum [closed]
Thermal radiation is visible - infrared - part of ultraviolet.
I wanted to know and more importantly have reference materials related to
What formula decides absorption spectrum of a substance.
And ...
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Acoustic absorption coefficient of Metals
Which non toxic Metals have the lowest Acoustic absorption coefficient?
