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

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34 views

Where I could find values for rare earth metalls levels diagramm (Dieke diagram)?

The Dieke diagrams like this: could be easily found in internet. But it is impossible to determine from where they get values initially, everyone is making cross-links. I'm especially interested ...
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1answer
99 views

Why is an exciton only observed when we excite to the conduction band and not to other electronic level inside the bandgap?

Excitons can be observed when we excite electrons to the conduction band. I don't know about excitons being observed when we excite the electrons to an electronic level that would eventually be in ...
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1answer
25 views

What will be the effect of placing a light source very close to a photodiode?

What will be the effect of placing a photodiode really close to a laser source and what should be the appropriate distance between a light source and photodiode to get maximum output current?
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2answers
33 views

For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we get absorption lines?

For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we see absorption lines? Similarly, why do we see emission lines if the planet is hot on the ...
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1answer
84 views

Thermionic emission, delayed emission and predissociation

In molecular photodissociation, the thermionic emission, delayed emission and predissociation are the same? Otherwise, what is the difference between them? My question is not about the solids, but I ...
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2answers
55 views

How organic impurities in the air affects laser?

We have a Nd YAG laser pumped Optical Parameter Oscillator in our lab. A technician came to our lab (my professor called him for its maintenance) and while he was working on it, he told me that ...
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2answers
80 views

How hot is aurora?

Has anyone done research on how hot aurora is? I mean if it is plasma it should be hot and since it is emitting mostly green light due to nitrogen (~78%) in the air, could it then be considered that ...
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1answer
32 views

Absorption lines in the context of identifying elements in far away celestial objects

I understand that absorption lines are used to identify elements but how are individual absorption spectrums identified in the light that is received by a telescope?
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1answer
313 views

What is the secondary electron cutoff in ultraviolet photoelectron spectroscopy?

While the fasted emitted electrons comes from the fermi level of the material in UPS measurement, where does the slowest, which is called secondary electron cut-off orginate from? I really can't ...
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1answer
31 views

Calibrating the relative intensity of a spectrometer with a blackbody source?

I am trying to compare the relative brightness of H-Beta and H-Alpha lines using a CCD spectrometer. In order to correct for the different grating efficiency at the two different wavelengths. I took ...
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0answers
31 views

Absorption coefficient from HITEMP or HITRAN [closed]

How to calculate the absorption coefficient (for radiation) from HITEMP or HITRAN databases? Or where can I find some tables or plots for the absorption coefficient?
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1answer
59 views

Resolution in a Fourier transform spectroscopy setup

I am a bachelor physics student and as an assignment we had to perform measurements on an FT spectroscopy setup. Context. Our setup consisted of a Michelson interferometer through which the light ...
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1answer
23 views

Nuclear explosion wavelength data

I am looking for data source (or chart) of spectral data that is being emitted on detonation of nuclear or thermonuclear explosion. Reason I am looking is to see if this data has specific signature ...
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1answer
37 views

Is the temperature different and or salinity different can lead to different colour of the water bodies?

I had skimming on an article about Thermocline and Halocline. How can two seas not mix? However, I am still curious on: Why the effect of Thermocline and Halocline are distinguishable based on ...
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0answers
6 views

Spatial Resolution in Magnetocardiography

In the science paper called Development of an optical cardio-magnetometer by George Bison, it is mentioned that spatial resolution of 10-20mm is required for mapping MCG signal(page 52). What does the ...
4
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1answer
44 views

Unknown peaks on RBS spectrum

I was given a sample, that it is supposed to be a medium thickness Rhodium on top of an infinite silicon waffer. The experimental RBS spectrum along with the simulation looks like that Apparently, ...
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1answer
252 views

Why does the addition of paramagnetic ions decrease the spin lattice relaxation time of protons?

My question pertains to NMR (nuclear magnetic resonance). $T_1$, the spin lattice relaxation time of protons in water is about 2.5 seconds. If you add some $CuSO_4$ (copper sulfate) to the water the ...
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1answer
33 views

What causes the triplet state in Helium?

I am not familiar with the notation used on wikipedia (http://en.wikipedia.org/wiki/Triplet_state). Is there a more physcial way to explain the cause of the triplet state (maybe without referencing ...
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16 views

Spectrum calibration from wavelength to energy [eV]

If we have some spectrum on camera after spectrometer, how we plot the spectrum in Energy in eV. Lets say I know which pixel what energy is, how the intensity will have to change as function of E to ...
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1answer
23 views

Why is solar eclipse so important for sunlight spectrum analysis?

People wait for decades to catch the chance of a solar eclipse to observe the sun. Why cannot they do it every noon?
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14 views

Why photoelectron imaging is a 'complete' measurement?

In many articles and books, it says that photoelectron imaging gives a 'complete' information. What is mean by 'complete' measurement or a 'complete' information? Through photoelectron imaging ...
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1answer
55 views

Absorption line detected with a significance of $2.2\sigma$

What do we mean by the following statement? The SV $\lambda$ 786.46 line is detected with a equivalent width of $W = 22.7\pm10.2$ corresponding to a significance of $2.2\sigma$ How does one ...
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0answers
11 views

Interpretation of decay associated difference spetrum

We measured transient absorption spectra and we got $\Delta A(\lambda,t)=A(\lambda,t)-A(\lambda,0)$. If we use DAS (decay associated spectra) for interpretation, we assume that our data have this ...
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52 views

Interchange symmetry for states with identical particles

I was reading this web page about interchange symmetry for states with identical particles here: http://quantummechanics.ucsd.edu/ph130a/130_notes/node317.html The article states that the highest ...
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0answers
8 views

Dipole and multipole bound state anions: Do these bound electrons behave exactly like conventional electrons in the molecular orbitals?

Recently, I read about dipole and multipole bound anions. Dipole bound anions are those, if I understood correctly, when an electron is attached electrostatically on a neutral molecule which is polar. ...
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33 views

how does different colour wavelength intefere? [duplicate]

Say a red colour with 400nm mixes with blue colour with 700nm, but out of phase by a little. What would be the resultant colour? I would know how to represent the resulting wave mathematically, but ...
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1answer
2k views

How do we know the temperature on the planets?

I was watching a show and they were saying that the temperature of Pluto (I know it is not a planet) is about -300 degrees. I know that depends where in the orbit Pluto is, but how do we determine ...
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2answers
137 views

Self-study: resources for understanding Gamma spectroscopy

I work in applied mathematics and have no background in atomic physics. I need to have a good understanding of the principle and application of Gamma spectroscopy. I am ok to spend the needed time but ...
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0answers
23 views

On characteristic X-ray spectra and relative intensity

I am looking at the following image (from http://www.schoolphysics.co.uk/age16-19/Atomic%20physics/X%20rays/text/X_ray_spectra/index.html): and I want to know, of the two curves, which one ...
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3answers
1k views

Is there a light source that emits all wavelengths of visible light at the same time?

Many light sources like LEDs and lasers only emit a single wavelength of light. Is there a light source that emits all wavelengths of visible light at the same time?
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1answer
83 views

Relative weights in rotational bands of symmetric diatomic molecules

In an old paper, Ehrenfest 1931, the introduction starts off as follows: The band spectra of symmetric diatomic molecules show certain striking differences from those of asymmetric molecules. For ...
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1answer
61 views

Non Adiabatic Coupling Term in Born Oppenheimer Approximation

I am attaching a section from a text book (Conical Intersections Electronic Structure, dynamics and spectroscopy: David R Yarkony & Horst Koppel). Here I am not understanding the so called 'Non ...
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1answer
37 views

Why some electrons in ESR aligned their spin towards external magnetic and some against

Why some electrons in ESR aligned their spin towards magnetic field and some against?
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4answers
120 views

How do we demonstrate that all spectral colors exist in nature?

Spectral emission by elements occurs in discrete wavelengths. There are only about 118 elements. My question is whether there are pure colors either disfavored in nature or even disallowed? The sun ...
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1answer
28 views

Spectroscopy and the current state of our ability to determine the composition of extra-solar planets

I was interested in learning more about the status of our scientific understanding and technological instruments regarding extra solar spectroscopy. I am motivated by this almost 3 year old ...
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2answers
59 views

Raman vs. Brillouin Scattering

In my class notes, I have the two types of inelastic scattering described as follows. (Note that the "difference in energy" here is the difference between the incident frequency of the light and the ...
2
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1answer
34 views

How is “Band Intensity” related to absorption coefficient

I am interested in the linear absorption of 762nm light near a transition of molecular oxygen. I need to find some experimental numbers that will tell us how far the 762nm light will propagate before ...
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2answers
39 views

Doppler spectroscopy to verify Earth's speed around the sun

I'm looking for data points to check changes in $z$ as the Earth moves towards and away from a star. I'm finding lots of data for various objects [1] but lots of variation too (for eg, the results for ...
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1answer
47 views

Precision measurements on sodium doublet wavelength?

I'm currently searching for a good and reliable source where precision measurements on the wavelength of the so called sodium doublet ($D_1$ and $D_2$ lines) at approximately 589.0 nm and 589.6 nm are ...
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0answers
46 views

Saddle point and transition state of a molecule

During a transition of a molecule from one state to another, it pass through a transition state. This transition state, mathematically speaking, is a saddle point. That means, the second derivative ...
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1answer
43 views

Can scientists tell the energy levels of the atom?

In the hydrogen spectral series how did the scientists know the number of the energy level which the electron is moving from or to?
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1answer
42 views

Blackbody radiation and Spectral Lines [duplicate]

Blackbody radiation is thermal radiation from a hot object emitted over a continuous range of wavelengths. But why are spectral lines, lines (i.e., you only get certain wavelengths when an element is ...
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3answers
171 views

Why is spectrum obtained by sunlight, said to be continuous?

My sir spoke about atomic spectra today. Sir said that, unlike the spectrum obtained by analyzing the sunlight, the spectra of atoms are not continuous. I got a doubt here, i,e even the sunlight ...
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1answer
296 views

Understanding the Selection Rules of a Spin-Forbidden, Magnetic Dipole Transition in Molecular Oxygen

I am studying the transition from the second excited electronic state of molecular oxygen, $b^1\Sigma_g^+$ , to the ground state, $X^3\Sigma_g^-$. I know that the ground state has total angular ...
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0answers
23 views

What is the perceived color of a D-illuminant?

I am implementing a software that simulates the color of the sky. To do this, I use a model that takes as input the sun position and returns the Yxy components of a D-illuminant for each point of the ...
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0answers
27 views

Textbook on Diffusion and Diffusion NMR Spectroscopy

I am looking for textbooks ( Mathematical / Theoretical Physics ) that cover diffusion in general. Although it is not necessary that your recommendation covers it, I am also particularly interested ...
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1answer
250 views

Ba K Lines in a Cs-137 gamma ray spectrum

I'm looking at a spectrum for the gamma ray spectrum of a 137-Cs source and I'm not sure where the peak in the lower energies of ~32keV comes from. I understand that it's to do with some sort of ...
2
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1answer
82 views

Apparent color of flame as superposition of spectral lines?

In some cases one can identify a substance by the color emitted as it burns in a flame. A green flame might indicate the presence of copper. So here is the question. If we know wavelength and ...
6
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1answer
96 views

Meaning of generalized normal distribution

I asked a version of this question over on Math.SX, and never received a response… perhaps it will be more appropriate here. I'm looking at spectroscopic data (specifically a $T_2$ coherence decay ...
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1answer
111 views

What is decay associated spectra?

What is decay associated spectra? Suppose we measure the fluorescence intensity over different wavelengths and over time, we get: $$I(\lambda,t) = \sum_i^n \alpha_i(\lambda) ...