the practice of separating a signal by frequency (or sometimes energy or momentum) and analyzing the resulting spectrum.

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2
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1answer
22 views

Why Doppler shift is applicable to spectral lines alone?

In astronomical spectroscopy, Doppler shift is an important parameter. But why is it applicable to spectral lines alone, and not to the continuous spectrum in the background? Shouldn't the motion of ...
1
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0answers
19 views
+50

Plasmon quenching vs plasmon decay. What is the difference?

I'm reading an article "Quenching, Plasmonic, and Radiative Decays in Nanogap Emitting Devices" (pubs.acs.org/journal/apchd5). I don't understand the following: Counterintuitively, we evidence ...
0
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0answers
9 views

Infrared Camera spectral filtering with an uncooled camera? [closed]

I have been doing experiments with thermal cameras and stumbled upon CO2 detection. Having ordered a filter I was full of joy and immediately tried it out - nothing happened. So I talked to the ...
0
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0answers
9 views

Lorentzian nature of reflected microwave power in Electron Spin Resonance

Reflected microwave power has Lorentzian shape when plotted against frequency in ESR. How to mathematically prove this?
0
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0answers
8 views

Change in Q factor on tuning external magnetic field in Electron spin resonance experiment

Does the Q factor of the cavity resonator show a dip at the resonant value of the external magnetic field while performing an ESR experiment?If so, what is the physical reason behind it?
0
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0answers
28 views

Which Hydrogen Emission Lines Appear First?

When a blackbody is heated, it radiates photons. At low temperatures, there isn't much radiation at high-energy end of the spectrum but as the temperature raises, high-energy radiation becomes ...
0
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0answers
11 views

What photomultiplier failure causes a zero signal?

I have a photomultiplier detector that suddenly stopped working. Usually I would have expected damage to occur over time by overexcitation, leaving a distorted signal. Now I'm unsure whether the PMT ...
1
vote
1answer
22 views

Should I see evidence of neutron induced gammas on a background spectrum?

If I am looking at a background gamma spectrum taken from a neutron spallation source whilst the beam was off (IE in a shutdown period), should I expect to see emissions coming from neutron induced ...
1
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0answers
49 views

Calculating Natural Broadening of Emission Lines

I'm trying to demonstrate the small effect of Natural Broadening as compared to other types of broadening (Doppler, Stark, van der Waals, etc.) and my calculations don't match the accepted values. My ...
0
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0answers
16 views

How to calculate term symbols and quantum numbers in spectroscopic physics?

I am studying for an exam in Quantum and Atomic Physics, and I having trouble working out what all of the possible term symbols are for a given electron configuration. So for instance, if I have the ...
3
votes
1answer
21 views

Why is a notch filter required for Raman Spectroscopy?

It is my understanding that Raman Spectroscopy uses a notch filter (or sometimes an edge filter) to remove the light from the laser, so only the relevant Raman bands are present. However, if this is ...
-1
votes
3answers
53 views

What physical properties can't be predicted based on index of refraction? [closed]

If I tell you the real and imaginary parts of the index of refraction for all frequencies, name a property that can't be predicted based on that information. If you're assuming this is a gas, specify ...
1
vote
1answer
39 views

Why don't stars re-emit the photons they absorb, thus restoring a continuous emission spectrum?

If you shine white light through a gas, electrons can absorb sufficiently energetic photons to reach higher excited states. This produces gaps in the spectrum and it's how Helium was discovered. So ...
-1
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0answers
4 views

Dependence of low res spectrum of binary system on phase

How much a low resolution spectrum of a binary star system depends on the phase of the system? i.e., what's the difference in the spectrum if star1 is ahead of star2 or star2 is ahead of star1 or ...
1
vote
0answers
26 views

Role of Cavity Resonators in continuous wavelength-electron paramagnetic resonance(CW-EPR)

Why is it necessary to place the sample in a cavity resonator for obtaining EPR spectrum in CW-EPR? What role does a cavity resonator play in a CW-EPR spectrometer?
0
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0answers
15 views

Absorption cross-section in atoms

How could someone calculate the absorption cross-section for an atomic species, not only on a specific atomic resonance, but derive a result, for the dependence of the absorption cross-section from ...
0
votes
2answers
42 views

Characteristic frequency

Can you please give me shortest possible (bare basic definition) of the characteristic frequency of a spectrum? All that google gives me are books and articles where I don't understand a word.
3
votes
0answers
40 views

How come hydrogen produce spectrum in visible light

I am confused, how can hydrogen produce emission lines in the visible light region? the only excitation that can happen to hydrogen is from energy level 1 to any other energy level, all of that ...
2
votes
1answer
50 views

Why is intensity related to number of photons?

I have been reading up on Doppler broadening and have found a number of sources (for example here and here) which seem to be taking the number of photons in the range $[\nu,\nu+d\nu]$ to be the same ...
2
votes
2answers
55 views

How can only one valence electron in sodium cause doublet in spectrum?

The valence electron in sodium atom gets excited and moves to higher orbital say $3P$ and it then comes to the lower energy state $3S$ thus there should be only one line in spectrum (regarding this ...
1
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0answers
15 views

Why do NMR spectrums have the higher chem shift values closer to x-axis? [closed]

Im not understanding what the intuition is behind why the graph is represented like this? I understand that downfield = deshielded and will have higher ppm value which is closer to x-axis, but i dont ...
1
vote
1answer
21 views

Formation of Line Spectra in light of Bohr's Theory [closed]

I am reading about the electronic structure. It is written that when hydrogen's electron comes back to ground state from excited state, it releases energy in a specific amount according to Bohr. But ...
1
vote
1answer
21 views

Finding natural linewidth's

I want to check whether my fit parameter for the width of a Lorentzian fit on my digital spectroscopy data for Helium (the 5875 Angstrom line) is what you would expect from the uncertainty principle, ...
1
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0answers
29 views

Spectroscopy: The trustworthiness of reflected, refracted, and “mixed” light sources

Spectroscopy: If spectral lines are used to determine the composition of an object, wouldn’t the reflected light (e.g., from a star) that allows us to see non-luminous objects (e.g., planets, bolides) ...
5
votes
2answers
66 views

Why absorption spectum is not identical to emission spectrum?

Hydrogen emission and absorption spectral lines are typically depicted as the same: (source) However, in more complex systems, the emission and absorption spectra are significantly different. For ...
0
votes
1answer
35 views

Can we determine the surface temperature of stars other than the sun by using the black body radiation theory?

It is well known that the surface temperature of the sun can be determined by fitting the solar spectrum to the black body radiation spectrum. Is this scheme feasible for other stars? Possibly the ...
0
votes
1answer
59 views

Calculate how many photons hitting a sample that are absorbed

In the determination of the quantum yield of a photoisomerization, $\Phi,$ the following is needed $$ \Phi = \frac{\mbox{Number of "reactions"}}{\mbox{Number of absorbed photons}} $$ The photon flux ...
1
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0answers
20 views

How to calculate the magnetic field due to orbital angular momentum in the fine structure

How to calculate effective magnetic field due to the angular momentum L in an atom like Na(23)? I found an answer that we could imagine the case that the atom was orbiting the electron now and ...
2
votes
0answers
65 views

Estimating temperature with Boltzmann relation with split emission lines

I'm trying to estimate the temperature of a plasma through the use of hydrogen lines, $H_{\alpha}$ and $H_{\beta}$ using the Boltzmann relation: $$ \frac{ n_{2} }{ n_{1} } = \frac{ g_{2} }{ g_{1} ...
0
votes
1answer
9 views

The $^1S_0 \rightarrow ^3P_0$ transition in O III

Checking out NIST data, I cannot seem to find any data about a $p^2$ valence atom, such as O III, for the $^1S_0 \rightarrow ^3P_0$ transition. Obviously it isn't a electric or magnetic dipole allowed ...
0
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0answers
31 views

Selection rules in a finite quantum well

I have a finite quantum well made of two different semiconductors with different bandgaps and I want to calculate the different transitions between the energy levels possible that I calculated in that ...
1
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0answers
30 views

Variable speed of light impact on spectral absorption lines in distance luminous objects?

There are many other arguments as to the constancy of the speed of light (or more precisely, c). One thing I have been curious is what would the impact be on spectral measurements from distant ...
0
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0answers
12 views

Spectral Signature

I am interested in studying about spectral signature of various materials. I am working as an electronics engineer intern in a company which deals with Hyperspectral imaging. Working with spectral ...
0
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0answers
8 views

Could IR and Raman be measured simultaneously?

IR and Raman are measured using two different machines. Looking at the nature of excitation and at the way data is collected, it seems that these two measurements could be done simultaneously (or with ...
0
votes
1answer
22 views

What is the meaning of the magnitudes on the axes of this spectrum?

I'm taking a course on radiation physics and I've been given an spectrum by my professor (concretely it is a spectrum of $\left.^{22} Na \right.$). This is the first time that I come across this kind ...
1
vote
1answer
35 views

Stark broadening and Voigt fitting

I have LIBS spectral data acquired with a CT spectrometer of resolution 0.4nm. I fitted the Voigt profile into the spectral peak at $\lambda_0$. The lorentz $\Delta \lambda_L$ and the gaussian ...
0
votes
1answer
30 views

Where can I find the Auger emission spectra of the most common chemical elements?

I am looking for an online resource where I can find the Auger emission spectra of (most common) chemical elements, i need them for AES (Auger Emission Spectroscopy). Thank you.
6
votes
3answers
592 views

How can light emit three kinds of spectra?

In case of black-body radiation, radiation gives continuous spectra. Molecular spectra is an example of band spectra. Similarly, there's also the atomic spectra. Why are the spectra of light not same ...
0
votes
1answer
132 views

Exact meaning of “pi/2 pulse”

In studying Mach-Zehnder and Ramsey interferometers, I came across the expression "$\pi/2$ pulse". What does it mean exactly? I am working with a Bloch vector representation $(u,v,w)$ of a 2 state ...
0
votes
0answers
37 views

Sum rule in X-ray Photoelectron Spectroscopy (XPS)

What is the sum rule in X-ray Photoelectron Spectroscopy (XPS)? how can I derive it? Can anybody explain the principle of sum rule in XPS or in spectroscopy in general? How can I apply it to a ...
0
votes
0answers
39 views

Multi-photon excitation probability for a two-level system

If a two-level system with a lifetime $\tau$ is excited with a pulse of duration $t_{pulse}$, what is the probability of exciting more than one photon? For simplicity we can take it to be a $\alpha ...
3
votes
0answers
33 views

Book on spectroscopy (line dependency on parameters)

I am trying to find a book (undergraduate level) on Spectroscopy. I am interested in how molecular absorption lines depend on parameters like temperature and pressure (for example with gases). Can ...
2
votes
0answers
25 views

What is the origin of the naming convention for the various branches in vibration-rotational spectroscopy?

In vibration-rotational spectroscopy, the different spectral lines are grouped into branches for different changes in the total angular momentum, i.e. $$ \begin{array}{rrrrrr} & \mathrm{O} & ...
0
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0answers
55 views

Difference between three mutually complementary methods: Raman, Infra-red spectroscopy and inelastic incoherent neutron spectroscopy?

When I read the wiki on Raman spectroscopy, I found a paragraph explaining what system is suitable for using Raman and what others do not. It provide two other method as shown in title: infrared ...
0
votes
1answer
29 views

Why higher FAT level implies more signal in XPS analysis?

In XPS analysis, the FAT (Fixed Analyzer Transmission) parameter controls the electrostatic field of an emispheric analyzer, called Pass Energy $E_P$. The FWHM of a peak of signal is given by ...
0
votes
0answers
17 views

Gamma spectroscopy - Extractable information from peak significance changes?

Apologies for the title - I couldn't think of a better way to summarize my question I have a table which contains information on 60 gamma spectra taken over a total period of 20 days, from the hall ...
1
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0answers
46 views

Quantum beats and Quantum mechanical side of photosynthesis

I have two questions. One concerning quantum beats alone, another - process of photosynthesis. I am very well aware that there is strong evidence suggesting that mechanism that leads light through, ...
1
vote
0answers
52 views

Can one measure experimentally the average distance between the two electrons in the excited state of helium in the singlet versus triplet states?

$\frac{1}{\lvert\ \vec(r_{1})-\vec(r_{2})\rvert}$ is a hermitian operator so I am supposing there could potentially be an observable with this which might be experimentally measured. We can measure ...
0
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0answers
54 views

Beta decay - Relative probability of electronic conversion for different disexcitations energies

I'm studying, experimentally, beta decay phenomena. Internal conversion of electrons happens when we have a sobreposition between a excited nucleus with it's electronic cloud. The colision between the ...
2
votes
1answer
46 views

Antisymmetry requirement for the total wavefunction

My understanding is that if we are dealing with a system of two electrons, the total wavefunction needs to be antisymmetric only when the two electrons have same value of n and l ( i.e. they are ...