Questions tagged [spectroscopy]
the practice of separating a signal by frequency (or sometimes energy or momentum) and analyzing the resulting spectrum.
1,138 questions
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Judd-Ofelt theory for molecules directly on metal
I am currently dealing with Judd-Ofelt theory and wondering if it is applicable on molecules containing a lanthanide directly on metal. Does anyone know more about it? I usually find it applied for ...
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1 vote
1 answer
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Blazed transmission grating
I'm having trouble figuring out why the max intensity envelop (i.e. single slit intensity peak) would be separated from zero order of the grating, for a blazed transmission grating. In the left ...
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8 votes
1 answer
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Zeeman splitting of Mercury green (546 nm) line: why no spin-orbit?
I'm teaching the Zeeman Effect and have gone through books and other lecture notes. I understand why, for the sodium D-line, we need to include spin-orbit coupling and then apply the Zeeman shift to ...
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4 votes
1 answer
51 views
Nuclear spin degeneracy in Einstein coeffcient (e.g. ortho-/para-hydrogen)?
In general, the Einstein coefficient for sponateneous emission transitions between degenerate levels $n$ and $m$ of degeneracy $d_n$ and $d_m$ is given by $$ A_{nm}=\frac{64\pi^4\nu_{nm}}{3h}\frac{\...
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What are the main sources of systematic uncertainty in $Δα/α$ measurements from quasar absorption lines?
Studies like Webb et al. (2011) and King et al. (2012) have reported small deviations in the fine-structure constant, α, using quasar absorption spectra at high redshifts. These rely on precise ...
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Difference between graphing spectral irradiance by frequency versus wavelength [duplicate]
This web page includes two graphs, one of which shows the sun's spectral irradiance as a function of wavelength and the other as a function of frequency. On the first graph, the spectrum "peaks&...
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3 votes
2 answers
166 views
Photomultiplier tube behavior in a fluorescence detector
I am observing a fluorescence detection phenomenon which seems unexplainable and all the spectroscopists who I contacted consider this a puzzling behavior. I feel this is some fundamental property of ...
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Infrared modes and momentum conservation in amorphous solids
In the paper about infrared spectroscopy on amorphous materials I read the following In amorphous carbon, there is no k-conservation because of the loss of long-range order, and consequently all ...
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11 votes
4 answers
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Funny looking hydrogen spectrum
I am preparing a physics demonstration for high schoolers. The picture shows the line spectrum I see from a hydrogen (Balmer) lamp through a diffraction grating. The red line and the cyan line are ...
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1 vote
1 answer
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Distinguishing IR/Raman active phonon by their irreducible representation?
In spectroscopy, we label phonon modes by their irreducible representations. My question is, can we directly read out if a phonon mode is IR- or Raman- active based on its irreducible representation---...
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About Fourier Transformed Infrared (FT-IR) Data Processing Techniques and Normalization
I am new in the community so I am sorry in case this is not the correct place to ask this question. I have a question regarding the processing of Fourier Transformed Infrared (FT-IR) Spectrocopy data. ...
3 votes
2 answers
278 views
Analogy of X-ray edge singularity problem for longer wavelength
X-ray edge singularity means that when one uses X-ray to excite the core electron, one will see that the absorption cross-section exhibits a power-law divergence at a certain frequency threshold above ...
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What are Lu-Fano plots in spectroscopy?
Can someone explain to me the purpose of Lu-Fano plots? (spectroscopy)
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How do you deconvolute both Lorentz peak and Gaussian peak from the Voigt peak?
How do you deconvolute the Gaussian and Lorentz from the Voigt function? Typical deconvolution, I know, involves different peak positions. But for a case like this, where the peaks are at the same ...
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1 vote
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121 views
How to determine penetration depth of film using integral sphere setting UV-Vis data?
I am currently conducting research on polymer films and my current objective is to calculate the attenuation coefficient of the polymer film in order to determine its penetration depth. Using an ...
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