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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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1answer
64 views

from a spectrometer, how to determine unknown substance in water?

I created a spectrometer that produces nice clean wavelengths, I calibrated it using a fluorescent bulb. from that I can create a graph from the data. after which, I use the known position to of ...
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1answer
40 views

Noise reduction approaches in optical spectral measurement

I am using an optical spectrometer to measure some surfaces in the visible, and since the signal is quite noisy I wondering what would be the best way to reduce the noise. In particular, are there ...
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51 views

Cannot observe Raman signal from Styrofoam

I am trying to build a low cost Raman spectrometer. I am using a refurbished B&WTek spectrometer that I purchased from eBay. I calibrated the unit myself and found to be very sensitive and ...
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2answers
278 views

In extragalactic spectroscopy, what is D4000?

In relation to astronomy what is D4000? In my work I understand it is a good indicator of a stars age and I believe it is a spectral region, but I am having a hard time even finding resources to help ...
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2answers
259 views

How is hydrogen able to emit a light spectrum with only one electron?

When light is shined through hydrogen gas, three colors of light appear. The issue I have with this is that hydrogen has one electron, meaning somehow the electron has to be emitting all three of ...
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1answer
202 views

Can Rayleigh scattering explain the orange color of the Titan sky?

It is my understanding that Rayleigh scattering depends on both the length of the particle as well as the wavelength. Due to the similar lengths of molecular nitrogen and oxygen it is blue light that ...
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1answer
38 views

What are the benefits of direct sun viewing spectrometer over a backscatter measuring spectrometer to quantify trace gases in the atmosphere?

I am using a Pandora spectrometer and a MAX-DOAS spectrometer to quantify the amount of formaldehyde (HCHO) present in the troposphere and stratosphere in Fairbanks, Alaska. Both the spectrometers use ...
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216 views

How to cleave a perovskite single-crystal in vacuum?

I am trying to cleave the lead-halide perovskite in vacuum to study its intrinsic electronic properties using photoelectron spectroscopy, since it is difficult to remove surface adsorption without ...
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17 views

Tabulated Emission Lines beyond NIST

It appears that when it comes to atomic lines, the most complete table is provided by the NIST website, which is, verbatim, based on the tables of Basic Atomic Spectroscopic Data Handbook authored by ...
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2answers
470 views

Why is Scan Rate Measured in Hz, not Hz/s?

Spectrometers have a specification called scan rate. As spectrometers measure spectrum, one would think the units of scan rate would be like Hz/s - meaning, the bandwidth scanned per unit time. Like ...
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0answers
22 views

can a photons energy state be altered with magnetic force?

with respect to sunlight, is there any way to use a magnet to alter the energy impact of sunlight? more or less energy, or hotter vs cooler? All spectrums considered. visable, xray, gamma. Can a ...
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39 views

Trouble trying to simulate the color of a reflection spectrum

My goal is to estimate the color of a hypothetical (but realistic) surface through simulation of the spectrum of the light reflected on the surface. In the simulation, a light with known spectrum is ...
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0answers
43 views

What are some mechanisms that can lead to unexpected/anomalous spectral lines

I am studying fluorescent spectroscopy (laser-induced fluorescence spectroscopy specifically). In a particular atomic spectrum, there are some unexpected lines not associated with any known ...
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1answer
278 views

What is the difference between the dipole in IR and Raman vibrations?

In order for a vibration to be IR active, there must be a change in the dipole moment ($\mu$) of the molecule, which is given by: $\mu$ = $\sum$ q * r Where q is the charge magnitude and r is the ...
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1answer
45 views

Atomic spectroscopy with nuclear spin: hyperfine splitting

In $^{171} Yb$, nuclear spin $1/2$, there is a transition: $^{2}S_{1/2}(F=0) \rightarrow\; ^{2} F_{7/2} (F=3)$ In this paper on p.3 (top-left) they say that $m_F^{(f)} = 0$ at the final state $^2 F_{...
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2answers
39 views

Utility of Filters?

I'm relatively new to astronomy and I would like to better understand why we need filters. I understand the concept of the filter, I just can't understand we they are so useful. In other words, ...
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1answer
61 views

Mossbauer effect explanation.

I need to understand Mossbauer effect. Is there any simple explanation? So far I know, when an atomic nucleus emits a gamma-ray photon, the nucleus must recoil to conserve linear momentum. ...
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1answer
183 views

Given redshift how do I obtain distance in parsec? [duplicate]

I have a catalog I am experimenting with that has some spectroscopic red shift data available (in the range from 0.5-1) as well as total Ks (K -short band) flux data available, how would I go about ...
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1answer
42 views

What are Chopper Spectrometers and how are they different from Triple-Axis Spectrometers?

I've been reading about inelastic neutron scattering experiments. Recently encountered these two techniques. Can anybody please tell me why/when are these two techniques used?
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20 views

Is it possible to emit an arbitrary Spectral Color [duplicate]

I've been playing with frequencies of colors lately, and just out of curiosity, was wondering if we have technology to generate a spectral color from an arbitrary frequency (to some degree of accuracy)...
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1answer
106 views

Given a fixed spectral resolution, what is the minimum detectable redshift?

Given an spectral resolution $R$ (for example $R=1000$), what is the minimum redshift which I can measure? How is this related to the minimum velocity among galaxies? If this velocity is related with ...
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1answer
53 views

How feasible is the production of antimuonic atom?

How feasible is the production of antimuonic atom (antimuonic antihydrogen)? It would be interesting to study the 2S-2P transition in this bound state given that the mass of the (anti)muon is greater ...
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0answers
42 views

Quadratic relationship between amount of light and intensity

In a spectroscopy experiment, we were able to control the amount of light shining onto a sample by adjusting two small slits. By investigating the relationship between slit width and the intensity of ...
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1answer
30 views

What, precisely and clearly, is the difference between scanning-tunneling microscopy and spectroscopy?

Is there a clearer description of the difference(s) between STM and STS than that on Wikipedia? I also found one other site which gave an equally contradictory, overlapping 'explanation'.
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111 views

Why can we see the fundamental rotational-vibrational transitions of molecules like CO?

In rotational-vibrational spectroscopy, the "fundamental" transition is the one in the lowest electronic state between the first vibrational level ($\nu'=1$) and the ground level ($\nu''=0$). Since ...
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1answer
239 views

Colors sensitivity by human eye and light wavelength [duplicate]

I do not understand why human eye sees different colours from the LED TV/screen. Especially violet. For example, how we get yellow color on TV. There are 3 small diodes Red, Green Blue in LED screen ...
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1answer
27 views

Is there Seebeck effect on junction between same metal but with different isotopes?

I recently discovered Mössbauer spectroscopy and its explanation drove me to think we should observe the Seebeck effect between two similar metals but with different isotopes. The main reason that ...
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2answers
65 views

Different methods for measuring intensity of IR wavelengths

I am proposing a teaching experiment at my university for undergraduates to learn about black body radiation and part of it will involve measuring intensities of different near - mid IR wavelengths. ...
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1answer
92 views

What do the numbers and letters in the “Intensity” section for strong lines (emission) mean?

NIST has a website containing various tabulated spectroscopic data, including the strong lines for various elements. For example, here are the strong lines for Helium. On that page, you can see on the ...
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1answer
124 views

Obtaining photoelectron counts from known radiance

I am attempting to make a rough estimate of the counts seen on a CCD spectrometer assuming I know the spectral radiance of a calibration source. I understand that this is not the same thing as ...
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2answers
88 views

What does this notation mean: $\mathrm{O}_{2} \ \ a\,{}^{1} Δ_{g} ← X\,{}^{3}Σ^{-}_{g} $?

The notation (which I found in the abstract of this paper) is $$\mathrm{O}_{2} \ \ a\,{}^{1} Δ_{g} ← X\,{}^{3}Σ^{-}_{g}. $$ Any help with this? I understand it's talking about quantum states of ...
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0answers
107 views

typical gamma spectrum

I have a positron emission tomography experiment and for the preparation of this experiment I have to discuss a typical gamma spectrum. The x-axis is the pulse height and the y-axis is the counting ...
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1answer
194 views

Ramsey spectroscopy of atoms — Heisenberg Picture

I was reading this thesis on the Ramsey spectroscopy, which deals with Ramsey spectroscopy of a two level system using the Heisenberg picture. This topic is dealt with in the Appendix A.1 of the given ...
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0answers
83 views

Dielectric constants from refractive index and absorption spectra

I would like to calculate the dispersion relation (dielectric constants $\varepsilon'$ and $\varepsilon''$) from two spectra: refractive index $n$ and absorption (in %). I tried to use the relation $$\...
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1answer
79 views

What causes the relative strength of hydrogen absorption lines in stars?

Every star has it's own spectral classification due to its spectrum. For example, $F, G, K$ and $M$ stars have a calcium absorption line due to the calcium in the star. As far as I know, all stars ...
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2answers
69 views

Are there any celestial objects which emit radiation with non-blackbody spectra?

Insofar as the blackbody spectrum is a "reasonably" good approximation for the radiation of the sun and presumably every ordinary star, and discounting objects which merely reflect light of some ...
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3answers
944 views

What's the lifetime of the excited state when you shine light on molecules?

Let's say, when x-ray hits a molecule, an electron from an inner shell absorbs the energy and flies away, so there's a hole waiting for an electron to come down and fill it. How long does this hole ...
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1answer
386 views

Raman Scattering vs. Fluorescence (1-photon / 2-photon process) [duplicate]

I have a question considering the difference between Raman Scattering and fluorescence. I know that Raman Scataring is a non-resonant process, while fluorescence is resonant, that Raman scattering ...
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2answers
51 views

What neutron spectrum should be produced from a low level nuclear fission event?

I am trying to determine what neutron spectrum would be produced by a low level nuclear event (for example a tactical nuclear weapon). What ratio or combination of thermal, slow, and fast neutrons ...
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1answer
4k views

How do I pretend that my high resolution spectrometer only has low resolution?

I have a spectrometer with resolution high enough to recognize the fine structure in alkali metal. Now if I add these two peaks together and ignore the non-resonance part between them, what do I get? ...
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1answer
60 views

Where does the galactic electromagnetic radiation come from? [closed]

What mechanisms or physical processes are responsible for the emission of electromagnetic radiation in a galaxy in the different wavelength bands?
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1answer
41 views

Technical: Scaling FTIR spectroscopy results

I have atechnical which I hope can be answered by someone's experience. I'm studying absorption on a sample by FTIR spectroscopy and, to catch the signal coming out from the little guy, I'm using a ...
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0answers
32 views

Electromagnetic Wave Spectroscopy [closed]

If a material has a non-zero second order susceptibility and you are impinging two electromagnetic waves at frequency f1 and f2 simultaneously on this material, what is the maximum number of ...
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1answer
158 views

Designing a grism spectrometer

I have read about grism spectrometers, e.g. in the work by F. Sigernes, and would like to try to make my own. However, I have some practical questions regarding the design: F. Sigernes uses camera ...
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2answers
1k views

Why doesn't the ${\rm H}_2$ molecule have a permanent dipole while the neutral ${\rm H}\,{\rm\small I}$ has one?

According to the National Radio Astronomy Observatory, the $21\,{\rm cm}$ line of hydrogen can be emitted by the neutral hydrogen atom due to the magnetic interaction between the spins of the proton ...
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1answer
23 views

What are the detectors used to count electrons in modern day spectroscopic tools?

I was taking a course in electronics. Scintillation counters, Dynodes, Channeltrons are some of the common names in counting elementary particles. When I entered an XPS lab, I saw "Detector used: PSD ...
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1answer
72 views

Extracting spectra of individual stellar objects

When you look through a telescope into the heavens you see an entire patch of the sky in which there are many light sources. If I attach a spectrometer, with a diffraction (or prism), to the eye ...
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1answer
208 views

Deriving the 2s to 1s transition rate

The hydrogen $2s$ to $1s$ is forbidden so it has a long mean-life (0.125 s vs 1.6 ns). Fermis golden rule can be used to derive the $2p\to1s$, but it predicts a zero rate (I think) when applied to the ...
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2answers
149 views

21cm line of Hydrogen spectrum [closed]

What is the advantage that we have when we study about 21cm line of Hydrogen spectrum over others, in radio-astronomy?
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1answer
44 views

What do the Bessel & Brett, Buser & Kurucz and Cousins filters evolution with time tell us?

I have been studying different filters to observe galaxies and I'm not sure I completely understand what information one can take from, in particular, the evolution of difference of intensity in the U-...