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

learn more… | top users | synonyms

3
votes
1answer
92 views

Does the spectrum of Sol's emission change as it ages?

A follow-up to my earlier question How would one navigate interstellar space? that just occurred to me; albeit on a different tack. Sol is probably in a state of continuous flux. The change of state ...
2
votes
3answers
6k views

What is the difference between Raman scattering and fluorescence?

What is the difference between Raman scattering and fluorescence? Both phenomena involve the emission of photons shifted in frequency relative to the incident light, because of some energetic ...
0
votes
1answer
249 views

What is the reference spectrum?

What is the reference spectrum? I need to know how to calculate the reference spectrum of a wavelength 500nm.
2
votes
2answers
115 views

Driving a solution of optical isomer molecules with the resonant frequency

What happens when we drive a solution of optical isomer molecules (enantiomers) with a microwave radiation in resonance with the tunneling frequency of the molecules (the frequency of the transition ...
3
votes
2answers
1k views

Energy shift between hydrogen and deuterium

Stated: The atomic spectra of hydrogen and deuterium are similar however shifted in energies. So im trying to explain why it is that the emission lines are shifted and how they are shifted. Since ...
1
vote
2answers
308 views

How the spectrum of the hydrogen atom is checked/detected experimentally?

When solving the hydrogen atom, as a 2 body problem, we have the motion of the center of mass and the motion relative to the center of mass. The well known energy spectrum, $E_n$, that goes like ...
3
votes
3answers
306 views

How do NASA's Curiosity determine the elemental composition of Mars using spectrometer?

From this article on hindustantimes.com - Curiosity sends data about Martian surface: The resultant flash of glowing plasma is viewed by the system’s 4.3-inch aperture telescope, which sends the ...
-1
votes
1answer
234 views

What is electron momentum density in solids and molecules?

Can someone kindly help me to know how can i get electron momentum density for one orbital like home? what is the theory of electron momentum density? how can I derive electron momentum density from ...
3
votes
1answer
446 views

Enhance a home build spectrometer

I would like to build a home made spectrometer like it's describing here: http://coolcosmos.ipac.caltech.edu/cosmic_games/spectra/makeGrating.htm How can I improve this spectrometer? A prism from an ...
0
votes
1answer
261 views

Spectroscopic notation $s$, $p$, $d$, $f$, $\ldots$

$s$ is sharp, $p$ for principal, $d$ for diffuse, $f$ for fundamental. Where do all those term come from? I do not see any link with the corresponding shapes.
1
vote
3answers
520 views

How would you explain spectrum and spectral analysis to grandma?

E.g. what the light or sound spectrum is, what it's useful for - in very simple terms that a grandmother or a child would understand.
2
votes
1answer
732 views

How can I subtract Spectra?

I am writing an application that should allow to view and manipulate spectra (Raman). I am only given one normal spectrum consisting of 1024 coordinate points. Plus I have a background spectrum that ...
7
votes
1answer
590 views

Emission line width units

What do these units mean: the large velocity widths of emission lines (in AGN) are 2,000 - 10,000 km s^-1? I've looked for the answer but keep getting swamped in myriads of details. I want to know ...
2
votes
2answers
422 views

Why are overtones forbidden within the harmonic approximation?

In vibrational spectroscopy only transitions between neighboring vibrational states ($\Delta \nu = \pm 1$, $\nu$ being the vibrational quantum number) are allowed within the harmonic approximation. ...
1
vote
1answer
568 views

Calculating Kramers-Kronig using Mathematica [closed]

First of all, I know there is a Mathematica group in beta, but I don't think the problem of the following is directly a Mathematica issue. I am trying to calculate the change of the refractive index ...
2
votes
2answers
2k views

Why in professional spectroscopes diffraction gratings are used instead of prisms?

Why in professional spectroscopes diffraction gratings are used instead of prisms? I guess transparency is not an issue, as we need optics anyway.
2
votes
1answer
188 views

THT (Tetrahydrothiophene) absorption spectrum

I am looking for the absorption spectrum of THT. What is the best way to find these types of exotic material's spectral characteristics?
2
votes
1answer
278 views

Confusion concerning the use of wavenumber in exercise about Fabry-Perot etalon

In the exercise we are given that the spectrum of a light source consists of two spectral lines, which both have wavelengths around $500 \text{ nm}$ and the separation between them - given in ...
5
votes
4answers
206 views

Atmospheric interference and ground based stellar observations

Stellar spectra captured from ground based equipment needs corrections to remove atmospheric spectral noise. Is there an Internet site that shows specific amplitude and wavelength differences between ...
10
votes
1answer
3k 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 ...
6
votes
1answer
2k views

How do we determine what distant planets, stars etc are made of?

I remember this being covered somewhat back in school and I have casually read about it. I know it involves inferring from spectral analysis what physical properties an object may have right? Though ...
3
votes
1answer
281 views

Suns emission spectrum

I learnt that in astrophysical spectroscopy, the emission spectrum of distant stars is used to determine what they're made of. So why is it that our own Sun is emitting the whole spectrum ? (or is ...
7
votes
4answers
683 views

What does ionization of neutral Hydrogen have to do with “transparency”?

Most accounts of the early history of the Universe make some reference to (re)ionization as being the reason that the Universe becomes transparent after a period of opacity caused by the absence of ...
4
votes
2answers
104 views

Metal Dilemma: Only very few civilizations per galaxy

This is a question in the area of extraterrestrial life. While life may be possible without it, space travel is probably impossible without metal. Metal is created in stars and heavy metals (above ...
1
vote
2answers
165 views

Relationship of the abundance of an isotope and the vapor pressure

Say I have a sample of some alkali metal - Rubidium for example. A sample of Rubidium consists of approximately 27% $^{87}$Rb and 73% $^{85}$Rb. Does the vapor pressure of each isotope individual ...
5
votes
1answer
453 views

Why can free lithium atoms not take part in an Auger process?

Shouldn't it be possible for an incoming photon to excite one of the 1s electrons to a 2p state (or one of even higher energy) and then for the excited electron to drop back to 1s and kick out the 2s ...
1
vote
0answers
126 views

Linewidth pressure broadening due to organic molecules

In relation to atmospheric spectroscopy and some other gaseous spectroscopy applications where organic molecules are present in the vapor, does anyone know of any papers or resources on pressure ...
8
votes
3answers
447 views

Significance of letters in Hertzsprung-Russell (H-R) diagram

The Hertzsprung-Russell diagram that categorizes star types uses the letter codes O, B, A, F, G, K, and M to indicate a star's temperature/color. Hottest (blue) is O and coolest (red) is M. What do ...
2
votes
2answers
616 views

Absorption Spectral Broadening

I'm working on a research project involving absorption spectra of particulates in solution. I was curious if someone could clarify or direct me to a resource that explains broadening mechanisms ...
14
votes
3answers
293 views

What is the probability that a star of a given spectral type will have planets?

There is a lot of new data from the various extrasolar planet projects including NASA's Kepler mission on extra-solar planets. Based on our current data what is the probability that a star of each of ...
4
votes
4answers
435 views

Is it possible to see Fraunhofer lines with amateur equipment?

Is it possible to see Fraunhofer lines with amateur equipment? Would it be possible (with reasonable effort) to identify elements or is this hard?
4
votes
2answers
313 views

Resources and requirements for amateur spectroscopy

If I wanted to move beyond just looking through my eyepieces and taking photographs of astronomical objects, what can I do do move into astronomical spectroscopy? Are there any good resources for ...
6
votes
3answers
9k views

What is a spectrometer, and why are they so useful in science?

I've heard reference to many telescope and spacecraft that have a device known as a spectrometer, and I'm curious, what is the purpose of these device? What's the working principal behind them and ...
3
votes
2answers
3k views

Glycerol: refractive index & absorption spectra in 0.2-0.4um range

Could anyone suggest where can I find absorption spectra & refractive index of Glycerol? I am specifically interested in UV range, 200-400nm, everything I was able to find out was for standard ...
5
votes
2answers
2k views

Relation between total orbital angular momentum and symmetry of the wavefunction

My question essentially revolves around multi-electron atoms and spectroscopic terms. I understand the idea that the total wavefunction for Fermions should be antisymmetric. Consider as an example, ...
3
votes
3answers
2k views

Why do we take the first derivative of EPR/ESR spectra?

Apologies if this question is a bit too chemistry-flavoured. In electron paramagnetic resonance spectroscopy, there's a practically ubiquitous convention of plotting the first derivative of the ...
5
votes
1answer
4k views

Newton's color Disk

How does Newton's color disk work? Newton's disk - Take a circular white color disk, make 7 equal intersections and paint section with respective VIBGYOR colors, now when you spin the disk in certain ...
2
votes
2answers
2k views

How do electron configuration microstates map to term symbols?

I am trying to understand energy levels of electron configurations. I visited the NIST web site and discovered that the notation used here are called term symbols. After reading corresponding ...
2
votes
2answers
388 views

Do cosmological and Doppler redshift produce different patterns?

For a given black body radiation curve, would the changes to the spectrum resulting from cosmological expansion and those from Doppler effects be distinguishable on the basis of the shapes of the ...
2
votes
3answers
802 views

Unstable energy levels

Well, reading about "Raman Effect" I saw that when the electron absorb some energy, with frequency $ \omega_{abs} $, that is different from $ \omega_{n} - \omega_{n-1} \neq \omega_{abs1} $, it go to ...
3
votes
3answers
2k views

Why do stars have absorption spectra?

Absorption spectra are a result of light of a certain wavelength exciting an atom from a lower energy level to a higher one and at the same time being absorbed. However, the atom should eventually go ...
0
votes
1answer
366 views

Given temperature, composition, column density, and radial velocity, can I find the bulk flow of a gas cloud?

We've got a hot star in the middle of a gas cloud. We point a spectrometer at the star, calculating the following attributes of our line of sight at the star through the cloud: Total number of ...
12
votes
2answers
5k views

Why is a plastic bag transparent in infrared light?

This is a classic trick to do with a IR camera: Bu why is the plastic bag transparent, while the glasses aren't? I've also heard that water is not transparent in IR light. What causes this ...
6
votes
2answers
1k views

Converting between brilliance, intensity, and flux

This one should be a bit of a softball, but I can't find it explicitly stated anywhere on the internet, and my basic unit analysis doesn't seem to work. Suppose you have a beam of synchrotron ...
3
votes
1answer
224 views

How small of a depletion signal can the best modern mass spectrometers detect?

So I know the answer to this question varies widely across mass spec techniques, masses, and, of course, budgets, but my question is about the best case scenario for all of these variables (although ...
5
votes
1answer
770 views

Selection Rules in electron spectroscopy

How to derive the selection rules $\Delta L= \pm 1$, $\Delta S=0$ for electron spectroscopy?
2
votes
3answers
911 views

Photon absorption probability for a given molecule in gas phase

So I'm pretty sure I'm approaching this problem in the wrong way and I need some guidance (my first hint is that I think I'm thinking about a quantum mechanical problem too classically) Suppose there ...
4
votes
1answer
46 views

Do XAFS excitations and subsequent relaxations lead to vibrationally hot molecules?

I'm in the process of trying to understand X-Ray Absorption Fine Structure (XAFS) spectroscopy, but I think this question is more fundamental than merely as it pertains to XAFS. I think I don't ...
8
votes
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?
2
votes
3answers
141 views

Can a multipass x-ray absorption cell be constructed?

I've been trying to understand the various concepts behind x-ray optics compared to standard visible/IR optics like mirrors and such. However, the x-ray mirrors I've been finding typically have ...