Questions tagged [spectroscopy]
the practice of separating a signal by frequency (or sometimes energy or momentum) and analyzing the resulting spectrum.
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Does the RF magnetic field have to be uniformly constant for a coherent EPR signal
Consider a loop gap resonator for electron paramagnetic resonance which has static (but sweepable) magnetic field in one direction, "x", and a GHz RF magnetic field in a direction "z&...
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Oscillation in the FTIR spectrum
An FTIR spectrum was measured for me (device from Alignment and MCT Detector) and since I'm not very familiar with FTIR I'm looking for some advice. The absorbance spectrum was obtained by measuring ...
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Where can I find tabulated data for reflectance per wavelength (for Cu, Ag, Fe etc)?
I'm looking for a tabulated data for reflectance per wavelength for various materials for the visible light range. I found only images so far. Are there any spreadsheets with the raw numbers?
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Why do IR spectra of calculation and experiment differ?
Recently I was simulating the IR spectra ( 400-3500 $cm^{-1}$ ) of an aromatic-like molecule with DFT. Then I did a comparison to the available experimental data.
Most data fitted well together: ...
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Conservation of angular momentum in electric quadrupole transition
I know that We can classify radiative transitions of electrons between different energy levels as electric multipole transitions or magnetic multipole transitions.
My question is:
In electric ...
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Alternatives for $\rm He$ wavelength calibrator
Where can I find a helium wavelength standard calibrator? We have a Photo Research WC-100, but seems we can't get anyone to do a calibration for it due to its age. Any leads to new vendors or ...
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What is the difference between electric multipole and magnetic multipole transitions?
Are electric and magnetic multipole transitions are classified based on the nature of change in angular momentum of an electron during a transition between two states?
In electric multipole ...
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Understanding Gaia DR3 Halpha width lines
Gaia provides low resolution spectra from BP/RP filters and the values of equivalents width for hydrogen spectral lines are also provided in it's stellar database. How can there be negative equivalent ...
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Generalized Lotka–Volterra equations to explore filling of energy levels in mixtures of interacting diatomic molecules
Did anyone saw any application of Generalized Lotka–Volterra equations to explore filling of energy levels in mixture of interacting diatomic molecules. The idea is to consider molecular interaction ...
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Limitations of Spectral Sensitivity Of Color Negative Film
I am trying to gain some understanding of film curves provided by the manufacturers of the film and I am confused about the Spectral Sensitivity curves. Take this for example (Screenshot of Kodak's ...
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Why is the Sun’s emission spectrum shaped like this?
The Sun emits more at $450-600 \,\rm{nm}$ than a black body of the same effective temperature would, it also emits far less UV.
I’ve heard this is due, in part, to the fact that the Sun doesn’t have a ...
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Using Gaia Passbands with $L_\nu$ coordinates
I am trying to find the coordinates of my bundles of gas on the gaia ($G,G_{bp}−G_{rp}$) hr diagram. I have its spectrum in luminosity $\nu L_\nu$ coordinates. Thus far, my attempts have mainly been ...
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How "wide" are absorption and emission lines?
There are various absorption lines that correspond to the difference in energy levels between electron orbits. E.g. the https://en.wikipedia.org/wiki/Lyman-alpha_line correpsonding to the difference ...
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What machine learning technique can help generate spectrum line profiles?
I'm trying to work with Calcium-K line profiles from the Sun.
Image for reference. Please ignore the labels on the image and note that my profiles are not in image format (more info below).
I have ...
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Gamma Spectroscopy Scintillator for X-ray Fluorescence
I have been reading into X-ray and gamma spectroscopy. I have found that they can both be done with scintillation detectors and work off similar principles.
That is to say that when a sample is ...
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Spectrometer resolution in Atomic Spectra
As we try to refine our spectrometer better and better each day, like first we observed doublets in Hydrogen atom, then we observed fine structure's in hydrogen like and in many heavy elements. Then ...
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Hydrogen atom laser spectroscopy and Lamb shift
To sum up I am trying to figure out measuring Lamb shift with precission laser spectroscopy experiment, and I cannot quite put my mind on it. I know that 1S-2S measurement happened through 2PA,Balmer ...
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What is the cause of "S-shaped" Raman spectra?
I'm doing Raman on graphite and graphite flouride (GF) obtained from suppliers for comparison with material I'm working on. For graphite, I get spectra which is consistent with literature data.
...
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Underestimation of peak wavelength by Wien's law for stellar spectra
I plotted some simulated stellar emission spectrums from PHOENIX which also each came with their respective effective temperatures. With the effective temperatures, I used Wien's law to estimate the ...
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Why the tapered optical fiber which dipcoated with rGO didnt give significant changes of voltage inside Photodetector?
I already cut it carefully the jacket out from cladding, and then use ethanol to rub the cladding so the core can be dipcoated with PVA-rGO solution.
Now I can see higher voltage depends of how much ...
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What is the state of the art in nanophotonic biosensing?
Over a decade ago I've been doing research in nanophotonic biosensing and all the reviews from those times were very impressive. Some plasmonic structures were capable of single-molecule detection and ...
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Count vs Count-per-channel
Hi there Wise people of the internet,
I am trying to do analysis some data gathered from a gamma scintillator setup, its stored in root.
So i have to do some coincidence measurements, and i found that ...
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How do degenerate states affect molecular absorption?
Molecular absorption of light is related to the transition dipole moment according to the equation from Hilborn, 1982:
$$\sigma(\omega)=\frac{\pi \omega}{3\epsilon_0\hbar c} \frac{g_2}{g_1}\mu^2\rho(\...
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Why doesn't optical pumping work when there is no external field to cause Zeeman splitting
I discovered a strange phenomenon in an experiment related to optic pumping and magnetic resonance.
In this experiment, I optically pump electrons in Rb85 to the $5S_{1/2}, F=2, m_{F}=+2$ state and in ...
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Does Thomson and Rayleigh Scattering cause any change in rotational and vibrational energy of an electron or atom?
We know from molecular spectroscopy that incoming light on a molecule can change a molecule's rotational, vibrational and electronic energy levels.
If the incoming light is,
on the far-infrared and ...
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At what distance can I assume peculiar velocity is negligible compared to expansion velocity, to use Hubble's law?
I am working on a high school physics assignment and am trying to figure out a method to determine if the star is a giant or main sequence from its spectral and photometric data (from SDSS). I picked ...
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Why is the solar spectrum at the surface of the Earth strongest in the visible light range? [duplicate]
I watched a CrashCourse video saying that nuclear fusion of $\rm H$ to $\rm He$ in the sun radiates mostly gamma rays. Then why are the lights that come to Earth comprise mainly of IR & visible ...
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Spectroscopy: rotational, vibronic transitions and highest peaks
In spectroscopy, the highest peaks in the absorption spectrum are those that are associated with the most probable energy transitions in a molecule. The most probable transitions are those in which ...
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Why tetragonal Tanabe-Sugano diagram is not just a splitting of octahedral one?
It is known that electron energy levels will be split when the symmetry reduces. For example, $T_1$ symmetry will split into $E$ and $A_2$ when the octahedral crystal field has a tetragonal distortion....
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Expressing rotational energy levels in temperature units
Let's say we have a molecule whose energy levels can be expressed as $E_r = B J(J+1)$ where $B$ is the rotational constant and J is the rotational quantum number. I've seen everywhere in the ...
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Hydrogen spectrum for transitions of $\ell$, $m_{\ell}$
In this question, there is a spectrum exhibiting transitions corresponding to the azimuthal quantum number $\ell$ of a system corresponding to a spinning $\rm{Cs_2}$ molecule.
Regarding hydrogen-like ...
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Explanation about the rotation spectrum from cold $\rm Cs_2$ molecules
In the book Mécanique quantique (Jean Dalibard), there is an example to illustrate the quantification of the $L^2$ squared angular momentum.
This example is extracted from A. Fioretti et al, Eur. Phys....
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What defined the frequency of a pulse if not its periodicity?
When reading about time-domain spectroscopies, it is stated that via the Fourier transformation of a pulse we can obtain its frequency domain information (as you can see in the figures below). This ...
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Spectroscopy: Yellow vs Magenta
I have a knot about the "secondary" colours and its spectra.
So If I look the spectra of white light, I can see that yellow, which is between R and G, has some wavelength. If I do an ...
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Can flute produce coherent radiation?
A flute is a wind instrument in which the interaction between a player supplying a modulated jet stream and the column of air in the cylinder result in the formation of longitudinal sound waves.
The ...
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Do these two separate light pulses (in sequence) interfere in this scenario? Why or why not?
This question is inspired by the recent "double-slit experiment in time" experiment that was popularized. See here and here. I have not looked into the original paper in detail, so my ...
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Dielectric tensor and electron energy loss spectroscopy (EELS)
Electron energy loss spectroscopy (EELS) is related to the imaginary part of the inverse dielectric function $−𝐼𝑚(𝜀^{−1}(𝑞,𝜔)).$
If the dielectric function $\epsilon(q, \omega)$ is actually a ...
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Can I find the surface temperature of the Sun using a spectrometer?
So I have a high school physics project and I essentially have this experiment idea where I use spectroscopy to find the surface temperature of the sun. Now I'm essentially going to assume the Sun is ...
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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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Why is Aluminium and Magnesium used as anodes in X-ray sources for X-ray Photoelectron Spectroscopy (XPS)?
Is there any particular reason for using Al/Mg Kα rays in X-Ray Photoelectron Spectroscopy?
I read that the energy of the X-Rays produced by taking these elements as the anode materials can decrease ...
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Why no dark lines for black body? [duplicate]
Black body is an object, hence it's made of atoms. Depending on what atom it consists of, that's how the emitted spectrum should be in my opinion. If it contains hydrogen, absorbed light on black body ...
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Zeeman effect on a superposition state
I am currently studying Magneto-optical trap(MOT). When a photon absorption takes place, there is a transition of an atom from an initial state to a final state (more accurately an electron in the ...
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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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How cosmologists know if the observed redshift of galaxies is due to expansion and not intrinsic to the galaxy?
Is there a way to experimentally test if the cosmological red shift observed is due to the expansion or intrinsic to the galaxy? If anyone knows how to do this or how to extract from the data please ...
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The solar spectrum on the time domain
This is the solar spectrum by wavelength:
By formula $c=f\lambda$, we can plot the solar spectrum over the frequency domain:
Then we can conduct inverse Fourier transform to transform the plot into ...
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Why can’t we see atoms in an optical microscope?
I know, the answer to this question may seem obvious: The resolution/magnification of an optical microscope is limited by the minimum wavelength one uses. This is due to the diffraction limit.
However,...
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Why is first line of Lyman series considered largest ultraviolet wavelength in hydrogen spectrum
I was reading a book which contains a numerical question about largest wavelength of hydrogen spectrum in ultraviolet region. In the solution, it mentions the largest wavelength in ultraviolet region ...
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What is the science behind coloured shadows?
Why are colour shadows formed? I have three coloured glasses in my house and If I keep my hand in its light path, I am seeing coloured shadows on the opposite wall.
Why is this happening?
Also ...
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Why the broadening of coherence peak in superconducting spectrum is described by an imaginary term?
From Phys. Rev. Lett. 41 1509, the density of states of superconductor is
where iΓ is the broadening part.
Can anyone tell me why the broadening can be decribed by an imaginary part, what is its ...
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How to identify the composition of sun if it is treated like a blackbody? [duplicate]
The sun is usually assumed to be approximately very close to a blackbody, but using spectroscopy it is concluded that the sun is made up of Hydrogen and Helium because the lines corresponding to those ...