Questions tagged [spectroscopy]
the practice of separating a signal by frequency (or sometimes energy or momentum) and analyzing the resulting spectrum.
653
questions
0
votes
0answers
3 views
S-W correlation plot from positron annihilation Doppler broadening spectroscopy
From Doppler broadening spectroscopy, we get the S-parameter and W-parameter. I found a S-W correlation plot in many research papers. What information does this plot provide?
-1
votes
1answer
34 views
Black body radiation and line spectra
Firstly, Blackbody radiation and line spectra are both a phenomenon of energy emitted(EM), but why is the blackbody radiation spectrum continuous while line spectra is not continuous?
Secondly, ...
3
votes
0answers
36 views
How is a spectrometer is calibrated for intensity?
For the case of spectrophotometers, we can easily calibrate the device(intensity wise) taking the light source inside the device as the reference, without any need of precise knowledge about its ...
0
votes
0answers
25 views
What are the deciding criteria for occuring of reflection, absorption, Emission, refraction and burning? [closed]
Why does some objects reflect, refract, absorb, emit and burn, when electromagnetic wave is thrown on them? I want to know all these things at atomic and molecular level.
0
votes
1answer
29 views
Does the spectrum of two-beam interference also show an interference pattern?
I know when you interfere two beams you get an interference pattern with a fringe pattern of λ/(2*sin(θ/2)) in physical space. It seems that there must also be modulation of the spectrum. Is this ...
0
votes
0answers
20 views
Is there a difference in wavelength emission spectra of ZnS:Ag when its irradiated with protons vs. gammas?
How would I measure this, because I couldn't find this information in literature as of yet? I have neutron (to produce protons by recoil) and gamma sources, but I don't have a pure neutron source, and ...
0
votes
0answers
6 views
Electronic transitions between sublevels
Is there any rule that says about electronic transitions between sub energy levels? Example only l =+1 or -1?
0
votes
0answers
11 views
Fitting Beta Emission spectrum data according to fermi function
I was trying to fit beta emission spectrum data to the equation
$$\tau(E_e) \propto (E_e^2 - m_e^2 c^4)(Q-E_e)^2\frac{E/c}{\sqrt{E_e^2 - m_e^2 c^4}}.$$
However, on making a custom equation in Origin,...
1
vote
0answers
18 views
Flame under immense pressure and moderate temperature
Consider the flame inside a rocket engine's pre-burner, where the pressure is truly immense (400~600 bar) but the temperature is quite mild (<1500 K), and the flame is of the premixed type. Under ...
0
votes
0answers
9 views
Taking out % contribution of a zero order state from an eigenvector - dipole calculation
I am doing an analysis of a theoretical spectroscopy calculation. I take an eigenvector (nx1) and dot it with many zero-order dipole vectors (nx3) to get the dipole contribution to my new eigenstate. ...
1
vote
0answers
40 views
Design and construction of a system identifying molecular nitrogen and water
I have read papers that use LIDAR-like and LIDAR-Raman systems that detect elements.
I want to measure the vapor water ($\rm H_2O$) and $\rm N_2$ of trees/agriculture using Arduino and low cost ...
0
votes
0answers
21 views
Electronic levels of Cadmium I
I am working on an assignment, and I have ran into a few issues. I tried asking my teacher, but he has been away and is not answering any E-Mails.
My problem is as follows:Considering Cadmium with $Z=...
-1
votes
0answers
52 views
Why did we need to build LIGO when we can just look at spectral shift?
We already know that the spectra of far away stars are redshifted because of an expanding universe. If we happen to look at the neighborhood of two merging black holes that are creating gravitational ...
0
votes
0answers
28 views
Difference between electrical conductivity and optical conductivity
Is there any difference between electrical conductivity and optical conductivity? How to explain it physically and is there any method available to connect them mathematically?
If I calculate carrier ...
1
vote
1answer
29 views
Mass and energy of radiation
We know that mass can be converted to energy and vice versa. So does the mass of molecules or atoms change when they absorb a radiation and go to the higher energy state?
0
votes
0answers
10 views
Is the integral of the spectral irradiance graph equal to the total energy absorbed?
This image is found on wikipedia:
My question is essentially: how can I read from this graph the actual total energy absorbed by the earth?
Is it true that the total red area is equal to the solar ...
0
votes
0answers
12 views
Does emission-spectrum of molecule equal sum of emission-spectrum of its components
Imagine a number of elements with known emission-spectra, that form a primary chemical bond of either
* ionic
* covalent
* metallic
type.
Does the emission-spectrum of the resulting molecule match the ...
0
votes
1answer
36 views
Radiation Emission in Rotating and Vibrating polar molecules
So, I am currently doing a course in Molecular Spectroscopy and I am finding some concepts very non-intuitive and very difficult to understand(maybe due to lack of my knowledge or the lack of ...
2
votes
1answer
53 views
Echelle grating
An echelle spectrometer has one low groove density grating (echelle) and one high groove density grating.
https://en.wikipedia.org/wiki/Echelle_grating
After the echelle grating there will be many ...
1
vote
0answers
37 views
How can you explain long lifetime of the Rydberg atoms? [duplicate]
Long lifetimes of the Rydberg atoms seems counterintuitive to me.
Intuitive explanation: the higher electron was excited, the more levels below became available for spontaneous decay. So the first ...
0
votes
1answer
143 views
Problem with the derivation of the Doppler broadening of atoms spectral lines
I have a problem with the derivation of the gaussian behavior of the doppler broadening of gas atoms specrtal lines. I will describe what I have done so the problem along the derivation could be ...
0
votes
0answers
17 views
Rebinning experimental data
I am working on a spectroscopy experiment and for each wavelength of a laser I have some counts. For the purpose of my question I will make up some data to illustrate my problem, in the table below (...
1
vote
2answers
110 views
Why is the spectrum of a star pretty much continuous? [duplicate]
I was reading about the development of the quantum theory when I got to the explanation for spectral lines. It's a topic that I've revisited many times but I came up with a question. I know that in ...
2
votes
0answers
29 views
How to identify properties of a concave diffraction grating
As a little side project I want to build a spectrometer. The main components are an entrance slit, a concave diffraction grating and a CCD sensor (also the electronics). I bought a used diffraction ...
0
votes
0answers
20 views
Equivalent Width: Strong and weak lines
Equivalent width of lines are known to characterize the overall strength of lines. However, if there are two absorption troughs, with the same equivalent width but different depth, which is possible ...
0
votes
2answers
17 views
Is there a way to precisely measure or infer the color of a material from a distance (~2m)?
I've recently started working on a graphics/SLAM project. I've encountered a problem that requires the measurement or inference of the color / spectral reflectance (and ideally albedo) of points on ...
0
votes
0answers
18 views
Auger electron spectroscopy
I am doing Auger electron spectroscopy on a sample. I found the differential spectra is not symmetrical. For example, oxygen peak in as received sample looks symmetrical but that for carbon is not ...
0
votes
1answer
20 views
Spectrograph difference between cross disperses and echelle gratings?
In echelle spectrographs, the presence of echelle gratings and cross-dispersers is common. What task does each one perform? Why are the cross-dispersers needed?
0
votes
0answers
16 views
Critical Point in Derivative of Absorbance
Background, and Question
I have a graph of $\frac{dA}{df}$, change in absorbance, over the change in frequency. I have a $A'= 0$ which happens to line up with a peak in absorbance, and a transmission ...
2
votes
3answers
72 views
High-purity silicon detector vs HPGe for gamma-spectroscopy
Is it possible to construct a high-purity silicon detector for gamma spectroscopy the same way HPGe detectors are made? Will it work when cooled to the same 77 K?
Why HPGe is mainly used for gamma ...
0
votes
2answers
37 views
What is absorbance and Transmittance?
I am currently doing some work in Spectroscopy, and I was wondering how are absorbance, and transmittance related? Do they have a domain, and range, how to read some sample graphs.
I was ...
0
votes
0answers
27 views
What does represents the concept of “magic wavelength” in optical frequency standards?
I cannot find on the internet references on this topic, so I'm trying to post my question on this forum, this is the first time I post here.
I can't understand the difference between "normal" ...
0
votes
0answers
82 views
Are there names for Helium (He) emission lines like the Lyman/Balmer/Paschen series in Hydrogen?
Just wondering if helium emission lines have names like hydrogen lines. For instance the Balmer series is:
$$H_{\alpha}, H_{\beta}, H_{\gamma}, H_{\delta}...$$
The Lyman series is:
$$L_{\alpha}, ...
0
votes
0answers
22 views
Relation between oscillator strengths $\log{gf}$ and the Einstein $A$-coefficient, rotational quantum number, …
I'm analyzing the spectra of M dwarfs. Some authors characterize the lines with the oscillator strengths $\log{gf}$ while others follow different paths with the Einstein $A$-coefficient. I would like ...
0
votes
0answers
17 views
Can a LGL (Lens-Grating-Lens) spectrometer have a non-zero geometry?
I am designing a transmission grating based spectrometer. Can the angle of incidence on the grating (alpha) be unequal to the diffraction angle (beta)?
I didn't think that they could be varied as i ...
5
votes
2answers
302 views
What is the cause for the fine structure?
What is the cause for the fine structure? I know that it describes the splitting of the spectral lines of atoms but I don't understand its cause,
any help is appreciated
1
vote
0answers
50 views
Has man ever observed the spectrum of a single hydrogen atom?
Were there this kind of experiment done before?
The spectrum we observed is radiated by huge number of hydrogen atoms in the gas, not by single hydrogen atom.
I know it's very hard to test a single ...
1
vote
1answer
41 views
Are there accepted spectral lines, or wavelength of light emitted, for the various neural and ionized atoms? If yes, where can I find them? [duplicate]
I am working with the redshift phenomena and analyzing the spectral lines of various emissions by galaxies. However, when I came to analyze the change in wavelength I was confused on what to compare ...
0
votes
1answer
23 views
Laser power inside a vapour cell
I have a laser beam whose power I measured to be x $\text{mW/cm}^2$. Furthermore, I measured the beam profile of the laser beam and therefore can estimate its intensity. I shine this laser through a ...
3
votes
1answer
34 views
Neutral lithium ionization energy for removing an electron from the $1s$ orbital
How much energy does it take to singly ionize a neutral lithium atom by removing an electron from the $1s$ orbital?
0
votes
0answers
30 views
Why infrared laser goggle looked orange?
So here's the thing, the laser goggle for UV light looked orange-yellow, which was sort of understandable, cause, if one want to block UV light, then the transmitted light ought to stay away from the ...
1
vote
1answer
63 views
What is so special about Paschen, Balmer and Lyman series?
I'm reading McIntyre's QM book and I see the same diagram ever so often:
He goes on to say:
I don't understand what he is trying to say with the last sentence. It seems he is saying, that ...
1
vote
1answer
35 views
Formation of Red and blue bands in the sky
Today at the time of sunset I saw this
The sky is divided into two parts one In red and one in blue which are very distinctive
Can anyone tell how?
The upper part of the image points towards the ...
0
votes
0answers
20 views
State coefficient in Kramer-Heisenberg-Dirac formula
I'm following the derivation of the Kramer-Heisenberg-Dirac formula from the book "Modern Optical Spectroscopy" and I'm having trouble understanding the wording and the derivation of the transition ...
1
vote
0answers
11 views
Why luminescence peak can move to higher energies with increasing temperature?
Can somebody explain me, why sometimes I see changes in position of luminescence maximum as temperature dependence in dielectric crystals? Is this is caused by band gap changes or maybe some exciton ...
1
vote
2answers
58 views
What software programs are recommended for background extraction and peak fitting?
I have an energy spectrum for various gamma sources. What software programs are recommended for background extraction and peak fitting in this case?
1
vote
0answers
27 views
Disk-like structures spectra vs ring spectra?
In the introduction to this paper (https://arxiv.org/abs/1803.06423) it is mentioned that disk-like spectra was observed in black hole X-ray binaries, when models would expected to be unstable (...
0
votes
0answers
19 views
Is it possible to do Raman Spectroscopy without having to use a filter?
We are doing our thesis regarding Raman Spectroscopy and we saw that the setup usually includes a notch or edge filter. I understand that it is important in order to remove the Rayleigh scatter of the ...
2
votes
1answer
48 views
(What causes) the *other* Compton edge?
The question
If one exposes a scintillator to a gamma source, one will observe two features for each characteristic energy in the source: a photopeak, due to complete absorption of photons, and a ...
1
vote
0answers
54 views
Photo Multiplier Tube (PMT) and charge sensitive pre-amplifier
I have an H7195 assembly type Photo Multiplier Tube (PMT) used to be tested for single photon measurement. I would like to use the dynode output to check the spectrum by connecting to a charge ...
