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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How to calculate the transition energy between $^2P$ to $^2S$ and $^2D$ to $^2S$ for sodium?
It's been known how to calculate the Zeeman effect. However how to calculate the transition energy between $^2P$ to $^2S$ and $^2D$ to $^2S$ for sodium($Z=11$)? ($^2P$ here meant term symbol ignored ...
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Principle series, Sharp series , Quantum defect, in Alkali Spectrum
Could anyone help me to understand the relation ship between principle series, Sharp series(https://en.wikipedia.org/wiki/Sharp_series ), electron spin, and atom's inner magnetic field etc. the ...
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How is “linewidth” defined for a damped driven oscillator?
Suppose we have a damped driven harmonic oscillator governed by the following equation of motion:
$$\ddot \phi(t) + 2 \beta \dot \phi(t) + \omega_0^2 \phi(t) = J(t) \, .$$
In the case that $J(t) = A \...
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Which device to measure UV lamp wavelength with high precision
Which techniques and devices are able to measure the wavelength/frequency of a UV lamp within the wavelength range of 50nm - 300nm?
Is a VUV Optical spectrometer the right device for this?
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42 views
Converting flux value given in Infrared
I have a flux value in the infrared band of 8 mJy at a wavelength of 80 microns that I want to translate into X-ray conventional ...
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1answer
66 views
Which colour comes out first from a prism?
When a narrow beam of white light is incident on a triangular prism. The speed of red light is maximum and violet is of minimum, red light bends less and travels less distance as compared to violet ...
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1answer
23 views
Selection rules in rotational spectroscopy- water molecule
The University of Liverpool maintains a ChemTube 3D page, where it says
http://www.chemtube3d.com/spectrorotcd0-CE-TEST-ROTATE-ALL.html
*> Highly symmetric polyatomic molecules, such as carbon ...
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23 views
Pressure inside spectrum tube?
I asked the firm who sells them here in Sweden, but they didn't know. I asked sellers on eBay, same answer. Is it different with say neon and hydrogen? Or is it the same pressure in all? I'm ...
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31 views
What's D lines for hydrogen like atom?
Could anyone tell me what's the definition of D lines for hydrogen like atoms?
(Not just those two lines for sodium.)
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1answer
13 views
Pump Probe Spectroscopy using in ultrafast diffraction
I am going through currently the experiments on "Ultrafast Diffraction". Would you please explain with some significant degree of conceptual details how I can find the transverse Doppler shift ...
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52 views
Gamma from U238 decay chain
Where can I find detailed information on the gamma background from the U238 decay chain?
Edit: Thank you for your replies. I need to find all the branching ratios and extract information of all the ...
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1answer
24 views
difference between infrared radiation and infrared night vision
I need th eanswer that are infrared radiation and infrared night vision are same?. Are Infrared night vision camera use IR rays?, if yes then why we use Infrared LEDs around the lens???
I am totaly ...
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1answer
37 views
Experimental Assignment of Electronic Transitions in Atoms (Grotrian Diagram)
Grotrian diagrams often taught in instrumental methods of chemical analysis to chemists. After a decade, I finally found the original book of 1927 by Grotrian "Graphische Darstellung der Spektren von ...
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1answer
45 views
Is discharge tube dangerous?
Are those gas discharge tubes dangerous?
I found atom spectra interesting, so I booked a 1.5 hour lab session at a local high school. The physics teacher gave me a few hydrogen tubes, helium tubes, ...
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1answer
51 views
What is line broadening phenomenon in quantum many body physics?
I have been reading Anderson's paper, "Absence of diffusion in a certain Random Lattice" and found the concept of inhomogeneous broadening. I couldn't really find a satisfactory explanation with a ...
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1answer
20 views
Why can't the electrons in Lamb-Retherford Experiment transition from 2S to 2P(j=1/2)
This experiment reveals metastable state and uses the fact that an electron in 22S1/2 can't go to the ground state as ∆l=0 is restricted. But I was thinking why doesn't electron go to 22P1/2 and then ...
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1answer
29 views
Does hydrogen reflect all visible wavelengths other than the wavelengths it absorbs?
I'm confused how reflection and absorption of photons work. For example hydrogen absorbs 4 wavelengths of light, but then that energy is emitted once the electron falls back to its ground state. So ...
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second-harmonic generation and inversion centers confined to a planar defect
Let's say that we have a phase which breaks inversion symmetry. Now lets say two domains of this phase meet at a plane such that the whole system now has inversion symmetry, with the inversion ...
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25 views
How can I determine, in what extent the fit to experimental data is good in Matlab?
I have experimental spectrum in which y-axis is intensity values, and x-axis is frequency values. Int - array of experimental intensities (y-axis). w - array of frequencies (x-axis). I know the view ...
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1answer
34 views
Light source needed in colorimeter and a spectrometer
I've found myself doing some research to ascert the differences when trying to assess the colour of a given sample.
I've found two main options, which are (1) a colorimeter and (2) a spectrometer.
...
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1answer
39 views
Predicting spectral lines
In the spectrum of some hydrogen-like ions the three lines are known, which belong to the same series and have the wavelengths 992, 1085, 1215 angstroms. What other lines can be predicted?
I don't ...
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37 views
Fourier Coefficients
Suppose i've a two voice samples v1 and v2. Comparatively voice v1 is louder than the v2. If both the voice is spoken by the same person.(Spoken normally as he speaks)
Is it good to state the ...
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2answers
103 views
What is the purpose of the slit in a spectroscope?
I built a spectroscope using a CD as diffraction grating. I understood how the grating works, but I didn't get why the slit is essential. Shouldn't it work even without the slit?
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1answer
45 views
How did Edwin Hubble estimate the velocity of distant stars?
I didn't know how to be succinct with my actual question in the title. My question is, how did he separate the components of the actual velocity of stars from that of the velocity due to recession (...
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18 views
Degenerate and Non-Degenerate Pump Probe Spectroscopy
I have just started my Msc Project, working on Pump Probe Spectroscopy. I will be most probably trying to setup a non degenerate pump probe technique, with the setup for degenerate type already done ...
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1answer
48 views
How was the electron in Rutherford's model producing a continuous spectrum and not a line spectrum?
How was the electron in Rutherford's model producing a continuous spectrum and not a line spectrum? What is the logical thinking behind that it will produce a continuous spectrum?
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1answer
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What are good, reliable databases of atomic spectra?
I am looking for a database of atomic spectra, which contains
atomic levels and their energies, electronic configurations, angular-momentum characteristics and lifetimes, and
atomic transitions and ...
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1answer
21 views
Principle of Energy Dispersive x-ray Spectroscopy
I have a question about the EDS
I don't understand how the detector can differentiate the Energy of incident x-ray simultaneously.
In my thought, the emitted x-ray from the sample have different ...
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1answer
17 views
Why sample is placed after the interferometer in FTIR?
In all image of schematics of FTIR I found (Wikipedia for example), the sample is placed after the interferometer:
Wouldn't this miss some emergent effects, such photo-induced absorption, since the ...
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42 views
DIY IR spectrometry - stray light (higher orders diffraction maxima)
Context: homemade IR spectrometer with diffraction grating.
Since
$$m \lambda = d \sin \Theta _{m}$$
diffraction maxima of higher orders from shorter wavelengths will be mixed with lower order ...
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Crude spectrometer using the Huawei P20 monochrome sensor
I am thinking of taking advantage of the Huawei P20 Leica monochrome sensor to create a crude spectrometer to measure the spectrum of different light bulbs.
I prefer not to use the optical ...
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1answer
78 views
Why do objects have a Natural Frequency? [closed]
Why should an object even have a natural frequency, why not vibrate at any other frequency? This just sounds nonsensical.
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Degeneracy of Polyatomic Molecules
I was given the following question to calculate in a problem class earlier this week:
A volatile pure liquid comprising a single polyatomic molecule is placed in a sealed sample cell in an FTIR ...
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1answer
21 views
Change in vibrionic energy in at atom at a higher excited electron state
I was studying the coupling of Vibrational and Electronic energies and was left confused at one aspect of the subject.
Consider the image showing a transition from one electronic state to a higher ...
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Confusion regarding the possible term symbols/spectroscopic terms for (2p)(3p) configuration
Note: I have read this answer but it still doesn't address my question in terms of the permitted symmetry.
I am learning about atomic states, and possible electron configurations. The first example ...
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17 views
Relative strengths of multipole contributions in atom photo-excitations
I have heard and read many times that dipole contribution to the photo-absorption matrix element is orders of magnitude stronger than quadrupole. To be exact, they are related as:
$\frac{\langle ...
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1answer
34 views
Vibrational and rotational spectroscopy
I don't understand why vibrational spectroscopy only has 1 intense absorption peak whereas the rotational spectroscopy has many separate peaks and the distance between the peaks is equal. $\Delta E\...
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2answers
26 views
Variation of electronic energy levels $E_{nl}$ of a many-electron with $n$ and $l$
Within the central field approximation, the electronic energy levels $E_{nl}$ depend on both $n$ and $l$.
For a given value of $n$, $E_{nl}$ increases with increasing value of
$l$.
For a given ...
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161 views
Is there a difference in the infrared absorption spectrum of a greenhouse gas when pure and when mixed with non-greenhouse gases?
According to the standard IPCC greenhouse climate change hypothesis a doubling of the preindustrial CO2 concentration of 285 ppm in the atmosphere - the current value is 405 ppm - would lead to an ...
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1answer
37 views
Frequency gap between neighbouring spectral lines
According to classical theory the atomic line spectra are discrete and their frequencies quantized.
Have the newer quantum theories changed anything since then, giving some other expressions for the ...
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1answer
40 views
Momentum Conservation for ARPES
I have a question about the principle of momentum conservation the modeling of ARPES:
https://en.wikipedia.org/wiki/Angle-resolved_photoemission_spectroscopy#Theory
We split the initial momentum of ...
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1answer
27 views
Which transparent material alters light the least?
I am making a spectrometer as my school project. It's main application will be analyzing the light emitted by various light sources. It measures visible, near IR and UVA/UVB radiation. I need it to be ...
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1answer
35 views
Determination of the variability of different spectra over shorter wavelength ranges from that of a single spectrum?
To pictographically explain, how do you convert Fig. 1 to Fig. 2?
Fig. 1
to
Fig. 2
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2answers
84 views
Why are there so many different “colors” in the line spectra of simple elements?
I understand that atoms emit photons of wavelength $\lambda$ when electrons transition to lower orbitals according to the equation $E = \frac{hc}{\lambda}$. Based on my understanding, those orbitals ...
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How to find all the possible spectral term for an atom configuration using LS coupling in the case of two unfilled subshells?
I'm not sure how to find all the possible spectral terms for an atom configuration where there are two shells not completely filled or empty.
Here the LS coupling is described for 2 electrons in 2 ...
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1answer
51 views
“For every line in absorption spectra, the corresponding emission line is present, but the reverse is not true”
I was studying atomic physics and read the line
for every line in absorption spectra, the corresponding emission line is present, but the reverse is not true
and I am not able to understand it ...
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1answer
22 views
how to estimate the error of FTIR spectra?
how to estimate the error of FTIR spectra in transmission, especially on the wavenumber ? please
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23 views
Why can't there be a direct absorption of a photon between Raman active states?
My question pertains to the fundamental difference between Raman spectroscopy and IR spectroscopy. Simply put, the Raman active transitions correspond to a change in the polarizability of the molecule ...
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1answer
30 views
In a frequency comb, how is $n$ determined?
A frequency comb from a mode-locked laser produces a series of spectral lines with $f_n = nf_r + f_{ce}.$
$f_r$ is the frequency of pulses coming out of the laser and can be measured directly via an ...
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A problem in spectroscopy [closed]
In this problem the wavelengths of emission are not equispaced. The answer is given as rigid rotator. We can write the energy as E=BJ(J+1) where J=0,1,2 etc. In order to justify the answer as rigid ...
