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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Two molecules with different polarizability in a EM field
If I have two molecules with different constants polarizabilities $\alpha_1$ and $\alpha_2$ and I send and EM field first on the molecule no.$1$ and then on the molecule no.$2$ so that the two ...
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The use of Principal Component Analysis (PCA) in Spectroscopy [closed]
Greetings there fellow users.
I am to prepare and give a seminar on Principal Component Analysis (PCA) in the subject of Laser Spectroscopy (aka solid state spectroscopy).
Now i am quite comfortable ...
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How to get rid of unnecessary signal in Photoluminescence Spectroscopy?
I am having some issues figuring out have to get rid of laser residues (might be) or scattering from the setup itself (please see attached pic).
In the lab, we have AUREA PIXEA 405nm laser, Horiba ...
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Examining isotope shift in ions vs neutral atoms - why use ions?
I'm currently deep-diving isotope shift (IS) spectroscopy literature. I've come across several papers that look at the isotope shifts of charged ions, and I want to try and understand why researchers ...
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A (Mostly) True Violet Pigment
Is there a "True Violet" dye or object? That is, one that reflects higher frequency light than blue, but doesn't reflect red light? All the chemical dyes I have found were part violet, part ...
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Why do metals appear as coloured in flame tests, while at room temperature they don't?
I'm not sure if this is more of a chemistry-type question, but my question focuses more on light spectroscopy than the chemical elements;
Why do some metals appear coloured in flame tests while they ...
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Does each spectral line of an atom/molecule have a unique lineshape?
A spectral line is determined by a particular transition in an atom or molecule. In reality, this line isn't infinitely sharp, but has a small distribution about the resonance frequency as a result of ...
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Estimate kubelka-munk coeffs at home
(originally i asked it on chemistry stackexchange)
I want to estimate Kubelka-Munk coeffs (absorption and back-scattering) for acrylic pigment. I want to do this only for three wavelengths that ...
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Is it possible that enriched iron can "lose" it's enrichness?
I am doing Mössbauer spectroscopy at room temperature while using my source as a $^{57}$Co and using as my absorber enriched iron. The result I got for some reason is much more similar to iron than ...
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Mössbauer effect literature's value resource
I am doing Mössbauer spectoscopy at room temperature on the following materials:
Enriched iron
sodium nitroprusside
ferric sulfate
by using the source as $^{57}Co$. So far the experiment go pretty ...
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Splitting of Sodium Line in weak magnetic field
Someone asked me two question which are
"On application of weak magnetic field the Sodium line arising due to the transition $^2 P_{3/2} \to ^2 S_{1/2}$ will split ideally into."
and
&...
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How do electrons know where to "drop to" when returning from an excited state?
The Balmer series only shows electrons dropping to the energy level n=2 and the Lyman series only shows those that drop to n=1. How did they restrict the electron's energy transition so that the ...
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Why would peaks of absorption spectra follow a Gaussian distribution?
I'm working on some code that is used for hyperspectral analysis.
In the older version of the code there were two main approaches taken when extracting features from the hyperspectral absorption ...
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Can you combine photons to ionise electrons?
I was talking with a friend about the photoelectric effect. I know that only light of a certain energy will eject an electron from a metal plate.
But consider this.
A photon (red) had the exact energy ...
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How to predict the time domain of pulse from an amplitude mask in frequency domain?
I am studying ultrafast spectroscopy (pump-probe) and I know that ultrashort laser pulses are used for the pump and probe. These pulses often contain multiple frequencies (i.e. polychromatic pulse) ...
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What is the relationship between density respose function and spectral function?
In ultracold atomic experiments, Bragg spectroscopy and Radio-frequency spectroscopy both can measure the property of the energy specturm. But one says that Bragg spectroscopy measures the density ...
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Which neutral atom-based quantum sensor is hardest to build/operate?
I am currently going through the presentation, "Sensing with neutral atoms", by Grant Biedermann.
I understand that, according to the talk, there are a large number of different sensing ...
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Thermally activated delayed fluorescence
In thermally activated delayed fluorescent (TADF) molecules, we consider 25% molecules in singlet first excited state and 75% in triplet, statistically, on electrical excitation after carrier ...
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Which are the spectral lines used to calculate the redshift?
I'm not sure if this is correct but I read in an article that the light of a distant star is first passed through a tube containing hydrogen gas and then through the prism for getting the absorption ...
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How is the light from distant stars obtained on a prism for calculating redshift?
Redshift has been used to map the expanse of the universe but what mechanism do scientists use to obtain and single out the light from a galaxy millions of light years away on a prism for getting the ...
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Splitting of $sp$-System due to LS coupling
How do I explain the splitting of $sp$-system due to LS interaction?
I think it is due to the magnetic field created due to the orbital motion of the electron, and that magnetic field splits the ...
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Quantum Defect in Atomic Spectroscopy
What is Quantum Defect?
According to a book I read, Quantum defect is defined as the physical Quantity which represents the degree of penetration of atomic trunk.
I am not able to fully understand ...
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How can we extract the Doppler shift of supernovae?
My understanding is that supernovae are used as standard candles, whose spectral lines indicate the recession velocity of the host galaxy.
But the material from the supernova is ejected at a ...
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What resources are you aware of and can recommend me to study and model spectral diffusion?
I am looking for textbooks, papers, etc. that cover this topic in some detail and would allow me to develop a simple model to use in my BSc thesis. I'm having a hard time finding the resources I need. ...
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Could a reflective beam expander deteriorate the lateral symmetry of a beam collimated from a single-mode optical fiber?
Background: I am currently concerned with getting a confocal time-correlated single-photon counting (TCSPC) setup ready for autocorrelation spectroscopy (fundamentally: fluorescence autocorrelation (...
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What is the Lorentzian line temperature coefficient and how is it determined?
The spectral Lorentz line shape is given by:
$f (\tilde{\nu} - \tilde{\nu}_0) = \frac{1}{\pi} \frac{\alpha_L (P,T)}{\alpha_L (P,T)^2 + (\tilde{\nu} - \tilde{\nu}_0)^2}$
Where
$\alpha_L (P,T) = (\frac{...
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Electronic vibrational rotational transition of electrons -- for a transition from $\Sigma$ to $\Pi$ how are P and R branches possible?
Suppose we have a diatomic molecule in a $^1\Sigma$ state, and it transitions to an excited $^1\Pi$ state. Note that the total spin of the electrons remains unchanged ($\Delta S=0$) as we can assume ...
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How can imaging spectrometers identify minerals on earth from satellites
I've seen descriptions of satellites orbiting earth which can create maps of continents with elements represented as colors on a map, how can they do this? I understand how a heated black body emits ...
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Collision-Induced Spectroscopy
In spectroscopy, are Collision-Induced Absorption and Collisional Excitation the same thing? If not, how are the effects they have on the spectra related?
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Generating a spectrum from relaxation times
I have some relaxation times that span several orders of magnitude. I'd like to plot the time spectrum and look at the frequency via a Fourier transform. I imagine there should be an appropriate ...
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How can they estimate exoplanet radial velocities using Doppler considering spectrograph resolving power?
I read that spectrograph resolving powers, the ratio of wavelength uncertainty to wavelength are like 1000 or 10000. Plugging this into the non relativistic Doppler formula gives a velocity ...
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Excitation of electrons from $3p$ to $3d$ in sulphur
In my book it is shown that sulphur in its excited state forms 6 covalent bonds with Fluorine to form SF6 but after the electron is excited does it not dexcite from $3d$ back to $3p$ and $3s$ by ...
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Can polychromatic light be produced from monochromatic light after passing through a crystal in transmission spectroscopy?
I have an optical setup where monochromatic light (573.5nm) is passed through a cuprous oxide crystal (Cu2O). This light is then passed through a monochromator, but the output light is actually ...
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Raman scattering collection geometry
I believe that most Raman spectroscopy measurements are carried out with the collection optics being at either 180$^{\circ}$(back-scattering) or 90$^{\circ}$ from the excitation source. Are there any ...
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Total brightness from emission spectra?
Some background: I'm looking to analyze stars through a telescope; I'd like get both the visual spectrum and the brightness of each target. I'd also like to have to build/carry as few instruments as I ...
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Determine Mass of a Star Using Electromagnetic Spectra
How do astronomers determine the mass of a star using spectra. In this answer here https://physics.stackexchange.com/a/503515, they state that the mass of a star is extracted from its spectrum and ...
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What does "Coherent" mean in coherent spectroscopy?
I find this on wiki: "Coherent or resonance spectroscopy are techniques where the radiative energy couples two quantum states of the material in a coherent interaction that is sustained by the ...
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What does the energy level referred to as ${}^3P_2$ refer to?
I am looking at a video about the latest nuclear-based quantum computer and it refers to energy levels by a notation I cannot decipher: for example $^3P_2$
$P$ refers to orbital angular momentum $\ell=...
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Why does there seem to be a disconnect between the spatial dependence of the order parameter and spatial dependence of the superconducting gap?
I am studying superconducting bilayers. My understanding is that the superconducting energy gap is the real part of the order parameter. In many theory papers describing S-N or S-S' contacts, they ...
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What is the function of the RF pulse in NMR?
I am slightly confused about the purpose of the RF (radiofrequency) pulse in NMR. The powerpoint of my course mentioned that an RF pulse perturbs the equilibrium magnetization and sets the nucleus ...
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What kind of material could be used as a diffraction grating for Xrays?
I'm trying to design a home-built X-ray fluorescence spectrometer with the following layout:
Building the X-ray tube is relatively simple, however I'm uncertain what material could be used as the '...
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If there were undiscovered elements (119 on) in a star's spectral lines, could we tell?
This question is kind of a companion question to this question on the creation of heavier elements via head on stellar collision. Both arise from me thinking about Przybylski's Star. This star has ...
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What causes a baseline to form in laser spectroscopy?
I am rather new to laser spectroscopy and recently came across some absorption spectra, produced by a MIR QCL. All of the spectra featured a prominent baseline, which can be roughly fitted by a 3rd or ...
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Extracting a mass attenuation coefficient for a dilute metallic gas for visible wavelengths
Currently, I am examining the attenuation of a visible wavelength laser with an initial intensity, $I_0$ by a metal vapor (in this case Aluminium) that has a density, $\rho_g$ of around 0.02g/cm$^3$. ...
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In FTIR, why is the sample interferogram out of phase with the background interferogram?
I am reading "Fourier Transform Spectroscopy" by Griffiths and de Haseth. In section 2.4 Apodization they state:
I do not understand the physics behind why the sample interferogram is out ...
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About normal Zeeman effect and Hydrogen atom
I think that the normal Zeeman effect is experimentally observed only when we can neglect the spin i.e. if we consider a spin-singlet state with total spin $S=0$. Since in the hydrogen atom there is ...
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Why does constructive interference occur at zero path difference in a Michelson interferometer?
I was reading Introductory Fourier Transform Spectroscopy by Robert Bell.
In chapter 9 "Beamsplitters" he states for self-supporting dielectric beamsplitters:
"There are $\pi$ phase ...
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Does carbon dioxide absorb visible light to any degree?
Does carbon dioxide absorb visible light to any degree?
I found this: https://www.dinosaurtheory.com/thick_atmosphere.html and I wondered whether several hundred atmospheres worth of CO2 really would ...
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How is that possible to isolate one particular star light from the others?
We can analyze distant stars by investigating the spectrum of their light. But we have billions of stars in the sky, and I wonder how it is possible to isolate the light of one particular star from ...
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List of lowest ground state energy transitions for all elements
Do you know of a list of the lowest ground state (s-p) transition for all/most/some of the periodic tables? It would be great if some molecules were included in this (water, CO2, etc). I am after ...
