Questions tagged [absorption]
A transition by which the energy of at least one photon is completely transferred to a material.
41
questions
0
votes
2
answers
70
views
Regarding the absorption property of a blackbody
Consider a blackbody of surface area $S_b$ and at temperature $T_b$. It is placed inside an evacuated chamber (to neglect all the effects of convection), with walls of chamber at temperature $T_c$ and ...
- 378
1
vote
0
answers
30
views
X-ray absorption edge, accurate theoretical predition possible?
It is well known that in X-ray absorption spectroscopy, the absorption spectrum shows discontinuities at some critical frequencies.
Is it possible to predict locations of these jumps theoretically? I ...
- 1,957
0
votes
0
answers
25
views
The absorption of infrared light for regular materials, like fabric wallets backpacks and clothes
I work as a brand partner for a company that produces a patch which strengthens the production of stemcells in the body.
The patches are activated with the help of the bodys own infrared radiation.
I ...
0
votes
0
answers
39
views
Absorption and emission spectrum terminology
Hi everyone recently i was looking for laser crystals and since I am an autodidact i was confused by the terminology and units of the optics domain. And specialy by the absorption and emission ...
- 1
3
votes
1
answer
89
views
How can the inverse of stimulated emission be distinguished from "normal" absorption?
A simple system with two energy states can absorb an incoming photon (of adequate energy) to get excited, and it can relax by either spontaneously emit a photon afterwards or get stimulated by another ...
- 6,820
2
votes
1
answer
47
views
Is there a way to use the optical transfer-matrix method to determine the absorbance of each layer in a multilayer stack?
I've implemented the transfer-matrix method to determine the the transmittance and reflectance of a multilayer stack of thin films.
I know that (ignoring scattering) the absorbance of the entire stack ...
- 123
1
vote
0
answers
44
views
What is the range of noon sun color temperature, when a light meter reports full expected sunlight (+/- epsilon)?
My question came from trying to find what uncertainty bounds, if any, I can assign to a color temperature sensor, without access to an artifact with a precisely calibrated output spectrum.
This leads ...
- 11
0
votes
0
answers
22
views
Temporal absorption coefficient from complex wavenumber
A complex wavenumber $k=\beta-i\alpha$ can be defined, that when substituted into a time-harmonic solution $e^{i(\omega t - kx)}$ yields $$e^{-\alpha x}e^{i(\omega t - \beta x)}$$
The first negative ...
- 21
1
vote
1
answer
57
views
Absorption spectra in films chemicals & dyes
For a science competition, we have to understand absorption spectra in films chemicals & dyes. But what is that? I've found resources on the absorption spectra of chlorophyll, but I'm unclear as ...
- 187
0
votes
1
answer
28
views
Why escape peak positions are calculated using emission energy and not absorbing energy?
For a X-ray monocromatic source, escape peaks energy positions are described by the difference between the incident energy and the fluorescence ($K_{\alpha}$ for example), like $E_{Escape Peak} = E_0 -...
- 1
1
vote
0
answers
23
views
Einsteins Coefficient of Absorption in solid state
What solid state parameter determines the probability of absorption (Einsteins coefficient B) in a material? Is it material dependent?
I think, I cannot say bandgap. Because if I have a source having ...
- 1,348
0
votes
0
answers
37
views
What happens after bulk gold absorbs a photon with its energy at the band gap or higher (wavelength < 500 nm)?
As is explained in the answers of this question: Why are most metals gray/silver? nicely, the responsible transition occurs between the 5d orbital and the 6s orbital, which is relativistically shrunk ...
- 121
1
vote
0
answers
30
views
How much gas is needed to produce absorption lines?
I am trying to know whether it would be possible to do an undergraduate laboratory experiment to measure absorption lines produced by a gas. The idea is to have a background source of light with a ...
- 636
5
votes
4
answers
2k
views
Aren't places where geodesics end singularities?
So of course when stuff falls into black holes, the geodesic for anything ends in that singularity. However, isn't it technically true that a light ray that originates from the sun and then hits the ...
- 1,534
0
votes
1
answer
39
views
What determines the wavelength in absorption?
When looking at absorption or reflectance spectra, say in the range of 400nm to 2500nm, you can see peaks (or dips) at certain wavelengths, that are characteristic for the material absorbing and ...
- 111
0
votes
1
answer
184
views
Complex Refractive Indices, Absorption, and Transparency
A complex refractive index is defined as $n = n_0 + \kappa$ where $n_0$ is the "standard" refractive index, and $\kappa$ is the optical extinction coefficient. The optical extinction ...
- 203
6
votes
1
answer
114
views
How do we know that the Sun is 71% Hydrogen by mass from emission/absorption spectra?
In my Intro to Astronomy ("intro" is very important, please keep responses as simple as possible) course, we're currently learning about light and electron orbitals and such, and I came ...
- 61
0
votes
2
answers
58
views
Why do the proteins in our eye have a continuous (bell shaped) absorption spectrum?
From quantum physics, I would expect that seeing e.g. red would excite the 564nm energy level of the Photopsin protein. I would also expect to only see (apart from some small smeering out) that we are ...
- 37
-2
votes
2
answers
129
views
Where does light energy end up? [closed]
Here's a gedankenexperiment:
In situation A you run $P$ watts of incandescent bulbs in a closed room for time $t$ (light and heat cannot escape the room). The room starts a temperature $T$ and ends at ...
- 147
0
votes
0
answers
20
views
Neutron double differential capture cross section
Can one define what is the double differential capture cross section for a neutron, and how one would construct an experiment to calculate the double differential cross section as a function of energy ...
- 499
1
vote
1
answer
45
views
Why only Lyman alpha transition suffer Redshift in the epoch of Recombination in Cosmology?
I was reading Baumann's book on cosmology (topic: Effective three level system). There it is said that in the epoch of recombination to form Hydrogen molecule two type of transition happens.
$$ 2S \to ...
1
vote
1
answer
106
views
450nm peak absorption [closed]
I am looking for an oxide compound (metal oxide, or similar preferably inorganic) which shows light peak absorption at 450 nm. I have troubles in finding the right compound, as most of the oxides have ...
- 113
0
votes
0
answers
29
views
Absorbance spectrum of common metal oxides
I am looking into metal oxides particles, and I wonder where can I find the absorbance spectrum of visible light of common avaiable metal oxides?
- 113
0
votes
1
answer
157
views
What is the influence of humidity on NDIR $\rm CO_2$ measurements?
The Question
I would like to use an NDIR $\rm CO_2$ sensor to measure $\rm CO_2$ in the 0.1-3% range. However, in the course of my experiments, humidity may vary from ambient (50-60%) up to nearly 100%...
- 101
2
votes
1
answer
75
views
Why we typically see no deeper into an atmosphere for an optical depth of 1?
In An Introduction to Modern Astrophysics (p.243), Carroll and Ostlie say that for a optical depth $\tau = 1$ the intensity will decline by a faction of $e^{-1}$.
$I_\lambda = I_{\lambda,0}e^{-\tau}$
...
1
vote
1
answer
147
views
Refractive index of titanium dioxide films as a function of wavelength for 400 C ° annealed films
I used UV-Vis/NIR spectrophotometer to extract the measurements of refractive index %R corresponding with wavelengths in the range of 190-1100 nm of TiO2 thin film deposited on FTO glass substrate. ...
- 11
1
vote
1
answer
206
views
Formation of emission lines, absorption spectra
If we spectroscopically observe a cloud of hot gas, which is on the whole not very absorbent, and which is not illuminated by a source behind it, we observe emission lines. How does this type of ...
- 439
0
votes
1
answer
66
views
Convolution or addition? Proper way to model overlapping absorption line profiles
Suppose you obtain a measured spectral line shape (let's call it 'envelope') which appears as a skewed/asymmetric voigt profile. You know physically that the envelope line profile has this skew ...
0
votes
0
answers
18
views
What effect, if any, does dissipative absorption have on aurora borealis? Why don't we see more colors as a result?
According to wikipedia, the aurora borealis is primarily caused by charged particles from the solar wind being redirected to the poles by earth's magnetic field and slamming into the nitrogen and ...
- 57
2
votes
0
answers
45
views
Physcial interpretation of term neglected in Rotating Wave Approximation
Consider an atom as a two-level system $|1\rangle, |2\rangle$ with energy separation $\hbar \omega_0$, which is interacting with a classical electric field $\vec{E}=\vec{E}_0 \cos(\omega t)$. This ...
- 447