Questions tagged [absorption]

A transition by which the energy of at least one photon is completely transferred to a material.

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Determine molar extinction coefficient from data set

How can you determine molar extinction coefficient from the graph of Transmittance vs Wavelength, where the solution concentration and thickness of cuvette are known and constant by using Beer-Lambert ...
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Ultra-violet optical transitions for $\rm ZnO$?

Is there any paper discussing the d(GAMMA3)-GAMMA1 optical transitions at around 7 eV for $\rm ZnO$ (W)? Will the negative effective mass/saddle point makes it a 2D (M1) transitions?
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Reconciling two descriptions of fluorescence

I am currently studying the textbook Infrared and Raman Spectroscopy: Principles and Spectral Interpretation, second edition, by Peter J. Larkin. Section 9. Selecting the Raman Excitation Wavelength, ...
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When does an electron release energy as photon and when as mechanical vibration?

Suppose we have a compound which has been given energy(either in the from of heat or light). Now, its electrons would absorb this energy and kick up to a high energy level. But, it would also re-emit ...
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Rate of Photon Absorption in a Semiconductor - Fermi's Golden Rule

In this paper, the rate of photon absorption in a semiconductor is given by Fermi's golden rule: $$ w_{1,2} = \frac{2\pi}{\hbar}\frac{e^{2}}{m^{2}c^{2}}\frac{2V}{(2\pi)^{3}}\int_{B.Z.}|\mathbf{A}\cdot\...
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Nonlinear Absorption Coefficient

How is Absorption Coefficient related to Susceptibility. I want to find linear, 3rd and 5th order absorption coefficient from linear, 3rd and 5th order susceptibility.
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Why does the real part of cavity transfer function equal the squared magnitude of cavity transfer function?

The normalized transmission transfer function for an optical cavity is something like $$ T(\Delta) = \frac{\frac{\kappa}{2}}{\frac{\kappa}{2} - i \Delta} $$ Here $\Delta$ is the frequency detuning ...
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Is reflection just a re-emitted wavelength at the electronic scale? Does reflection require absorption in the first place?

I'm researching on how different wavelengths choose to either reflect, get absorbed, or transmit through a particular material. I've read that transmission is when waves do not interact with the ...
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Emission of heat from absorption of light photon

So I've recently learned about photoelectric effect. It made sense at first, but when I try to combine it with what I thought I knew about emission and reflection of photon, things become rather messy....
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How to find the fraction of light absorbed by a surface?

How to find the fraction of light absorbed by a surface? What values do we need? I am trying to find the fraction of light absorbed by a surface when it's dry and when it's wet. I have something ...
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How to find the probability reflection at a liquid-air interface for a surface which reflects diffusely according to Lambert's law?

The smooth surface is air-liquid interface and the rough surface is let's say a t-shirt. The image above shows the probability of each reflection, and the $p$ value is the probability of the light ...
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How is absorption integrated in the simple Drude model?

What is the physical process of absorption in the Drude model? As far as I understood in the Drude model you only consider the electrons as classical particles and frozen ions. No other particles ...
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Absorption cross section for Nitrogen in the visible spectrum

I am trying to find data for the absorption cross section of Nitrogen at various wavelengths in the visible spectrum (~400-800 nm). I can only find data at lower wavelengths, however. Data from the ...
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Momentum matrix elements for two-photon absorption in semiconductors

I am trying to follow the paper "Two-photon absorption with exciton effect for degenerate valence bands" (to be found here: https://journals.aps.org/prb/abstract/10.1103/PhysRevB.9.3502). It gives the ...
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Two state system interaction with radiation - exact solution

Edited after comments. I can't seem to find (or derive) the exact solution of the two quantum state system absorption problem in the following formulation. Let's consider the general harmonic wave ...
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Below what threshold of intensity can a ray of light be considered absorbed?

Say I have a beam of light of intensity I. I'm modeling its traversal through a medium which absorbs light. As it travels, I reduce its strength by a certain specified factor. Below what intensity ...
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Nature of electromagnetic absorption by quantum and classical systems

Forgive me for lack of formality and possibly incorrect understanding, but hopefully someone can both help to explain the intuition and also add mathematical formalism. In classical electrodynamics, ...
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What does “Metal based electronic transition” means?

Recently I've been reading on the chiroptical activity of metal nanoparticles protected by biomolecular ligands, which have optical activity signals that are manifested in the metal-based electronic ...
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Black hole absorbing photons?

If a black hole has a radius that is not that much smaller than the wavelength of light emitted by the sun, and is at the same temperature, shouldn't it be able to absorb photons as well as emit them? ...
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Raman effect and IR absorption

Let's consider a molecule with N atoms, on which is shot a polychromatic IR beam. From the quantum selection rules, we know that in a single event of absorption only one of the 3N-6 oscillators can be ...
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98 views

How does the reflection coefficient change with scattering and absorption?

My professor of Biomedical Optics course asked us to think upon the evolution of the reflection coefficient with the absorption coefficient $\mu_a$, the reduced scattering coefficient $\mu_s'$ and the ...
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51 views

Fresnel equations & emission

As part of a project work I had to derive the absorption of a thin-film stack. It was a semiconductor between two oxides on a metallic back reflector. I used Fresnel equations and optimized the ...
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How does silver affect transmission of energy in the visible and infrared part of the spectrum?

A common method to prevent radio frequency and microwave energy from going through windows is to apply a microscopic layer of silver to the surface of the glass, either by attaching a film coated with ...
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Average distance travelled before absorbtion 253 nm photon in air

At first I wanted to use term "Mean free path" in title but I know it means other kinds of interactions too,not just absorbtion.What I really mean is mean free path but only for absorbtion. For ...
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Are Emission and Absobtion spectrum EXACT photographic negative for Hydrogen Sample?

If both are exact photographic negative, then is it true that the way an electron can deexcite (for eg.4$\to$1) in many ways like first 4$\to$3 and then 3$\to$1; absorption can too take place in ...
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Reflection, emission and absorption of light

When you shine a light on an object, some of it gets reflected and the rest gets absorbed. $A + r = 1$ Where r is the amount of light reflected per sec in $1m^2$ and A is the amount of light absorbed ...
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Are these statements about different emissivities correct?

I'd like to verify if my concluded statements regarding different emissivities are correct or not. And if not, why. 1 Two objects, one with an emissivity of 1 (object A) and one with a very low ...
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846 views

Integrated absorption coefficient

The absorption coefficient is usually defined as $$ \alpha(\nu)=\frac{1}{d}\ln\frac{I_0(\nu)}{I(\nu)}, $$ where $d$ is the thickness of the sample, $\nu$ is the light frequency, and $I_0$ and $I$ are ...
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What determines an emission wavelength after being pumped?

In this diagram, multiple emission lasing wavelengths are shown. What dictates which wavelength is lased? Is it random? Because this ion can be a four level or 3 level manifold due to the emissions.
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Why does an positive absorbtion coefficient imply impossibility of population inversion?

In "Radiative Processes in Astrophysics" from Rybicki and Lightman there is a chapter called "6.9 The impossibility of a synchrotron maser in vacuum": They prove that there can not be a synchrotron ...
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Acoustic decoupling of small mechanical resonator

I am trying to lock and optical cavity mounted on a small aluminium breadboard. I notice when locking that any sound, even quiet whispering seems to disturb the process, causing a 100hz fluctuation to ...
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Clarification regarding atmospheric opacity

I have taken a look at the related questions Can someone explain to me the concept of atmosphere opacity? and Why can spacecraft observe terrestrial gamma rays, but terrestrial observers not ...
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Absorption spectra of molecules library

Do you know where I can find a library with absorption spectra? I would like it if then I could input a wavelength and get back a specific value. More specifically I would like to see the absorption ...
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725 views

How to calculate the Refractive index of a glass sheet

My question is how to find the $n$ of a glass sheet with just aiming a laser beam to that. I've got lot of ways that let me find the $n$ ( Refractive index ) but I need the whole part of the ...
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Interpretation of decay associated difference spetrum

We measured transient absorption spectra and we got $\Delta A(\lambda,t)=A(\lambda,t)-A(\lambda,0)$. If we use DAS (decay associated spectra) for interpretation, we assume that our data have this ...
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How can one calculate the distance a particular sound will travel?

What do you need and how to calculate a distance traveled by sound? For example if you hit a bell with a specific amount of power how far will it travel?
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How to picture vibrational overtones of water?

Im trying to understand the colour of water. The absorption occurs because of some of the vibrational overtones of water. The absorption band at 698 nm (14300 cm−1) is a 3rd overtone (n=4) The ...
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Are there anti-reflective paint other than black matt paint?

I am trying to build a box where I will be testing some materials inside the box to take measurements of the irradiation. I need to make it so that the walls of the box do not reflect any radiation (...
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$CO_2$ absoprtion bands in atmosphere and impact of increasing concentration levels

I have a question to do with this graphic and the CO2 absorption band highlighted with a red vertical line. The image shows that nearly 100% of the IR energy in that band is absorbed in the ...
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How does evaporator coil absorb heat when a cool liquid is passed inside it?

My question is how does evaporator coil inside a refrigerator cools the inside atmosphere by absorbing heat? I am fully confused, how the heat absorption happens? This technically sounds confusing.
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The best range to measure the differences between glass, can and plastic

First of all, i'm Computer science student, so maybe the question is simple for this forum so i'm apologize and hope that i will found help here I working on recycle bin which automatically ...

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