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

learn more… | top users | synonyms

2
votes
0answers
105 views

Line-shape asymmetry in undergraduate Hydrogen-Deuterium experiment

I'm working as an LA (undergraduate TA) for an undergraduate physics laboratory experiment where students test the Bohr model and use reduced mass to determine the approximate mass of the neutron. In ...
2
votes
0answers
49 views

How large would the electric field need to be to split the mj -/+1 626.6 nm line of neon?

I am an undergraduate considering an extension on a quantum beats experiment with neon. The premise is to excite neon atoms coherently from a metastable 'ground' state into a superposition of excited ...
2
votes
3answers
65 views

What's the difference between frequency domain and time domain spectra?

If I have a mechanical oscillator and want to observe the dynamical behavior of the oscillator, is there any additional information to observe it in time domain and frequency domain? Normally, we ...
1
vote
1answer
52 views

What happens to light at sharp points? [closed]

At the tip of the sharp point shown, what will happen to light incident on it. This curiosity was invoked by a friend and also my childhood of watching shiny pointed swords in cartoons. Original ...
1
vote
1answer
77 views

Spectral series' formula of a given atom (other than hydrogen-like)?

The hydrogen spectral series is given by the Rydberg formula: The energy differences between levels in the Bohr model, and hence the wavelengths of emitted/absorbed photons, is given by the ...
1
vote
2answers
3k views

Full Width Half Maximum (FWHM) of a transmission spectrum

I have a transmission spectrum of a material which has been fit to a Lorentzian. According to Wikipedia here and here, FWHM is the spectral width which is wavelength interval over which the ...
1
vote
3answers
511 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.
1
vote
1answer
138 views

How much can a laser's position be fine-tuned?

Suppose you wanted to do a time-resolved experiment with a molecular beam traveling at, say, 300 m/s involving a mobile excitation (pump) laser that scans across the length of the molecular beam and a ...
1
vote
2answers
104 views

Do all elements spectrum lines fall within the visible light range?

I was wondering if whether we were extremely lucky to have found spectral (absorption) lines of astronomical objects because they fell within the visible light range or if there something intrinsic ...
1
vote
1answer
62 views

Continuous spectra of photons

I guess this is a basic quantum mechanics problem, but I'm not entirely sure of my answer. Suppose we have an electron in a hydrogen atom having the state \begin{equation} ...
1
vote
1answer
32 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?
1
vote
2answers
47 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 ...
1
vote
1answer
49 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?
1
vote
1answer
110 views

Can I prove boundedness of an operator without checking it for its whole domain?

(I don't have a direct reference so this is a little fishy and I'll delete it if nobody recognises what I'm talking about, but I though for starters I'll ask anyway) I've heard at university that if ...
1
vote
3answers
88 views

Can stimulated emitted photons be absorbed?

Typically a stimulated photon will be one of a pair with its stimulating photon. If the leading photon is absorbed by a particle in the ground state, will it then be re-emited by the stimulated ...
1
vote
1answer
558 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 ...
1
vote
1answer
54 views

Resonance Raman spectroscopy vs fluorescence

In Resonance Raman Spectroscopy we often want to avoid the fluorescence. But what is the problem with fluorescence . What we want is a shift between exciting line and emitted radiation and both can ...
1
vote
1answer
89 views

Where to find detailed measured emission spectra of all chemical elements?

I'd like to have something like this, but for single atoms and with more extended range of wavelengths. All I could find e.g. for hydrogen was lots of talks about Rydberg formula etc. and plots of ...
1
vote
1answer
62 views

Intereference rings by light transmission?

Recently I recorded UV-Vis spectra of liquids with a two-beam spectrometer (Perkin Elmer 900). Lack of proper racks for cells of 0.5 cm optical path length let me use a stack consisting of a 0.2 cm ...
1
vote
1answer
56 views

Limits of laser spectroscopy for determining size of a molecule or particle

Say you have a number of particles respectively molecules suspended in air. The diameter of the particles $d_{particle}$ are of the order 1 to 100nm. Can you actually, i.e. in practice, measure the ...
1
vote
1answer
98 views

Mysterious spectra?

In my blog post Why riemannium? , I introduced the following idea. The infinite potential well in quantum mechanics, the harmonic oscillator and the Kepler (hygrogen-like) problem have energy spectra, ...
1
vote
1answer
562 views

Calculating Kramers-Kronig using Mathematica

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 ...
1
vote
1answer
27 views

What is the 'triangle selection rule' in spectroscopy?

This paper states that However, the multiphonon relaxation bridging the $^5\!D_1$ and $^5\!D_0$ levels is a well-known exception because it is formally forbidden by the triangle rule and occurs ...
1
vote
1answer
74 views

Autocorrelation function for deterministic nonlinear dynamical systems

I am quite puzzled with the problem that spectral analysis has been either applied to noisy dynamical systems or to chaotic ones. I was wondering why nobody makes analysis of non-linear dynamical ...
1
vote
1answer
38 views

Why infrared absorption is a nonlinear technique?

I am looking for a good explanation and/or reference quotation explaining why infrared absorption technique is essentially nonlinear (eg. for carbon monoxide quantification). When using ...
1
vote
1answer
62 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 ...
1
vote
1answer
39 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?
1
vote
1answer
32 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 ...
1
vote
1answer
70 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 ...
1
vote
2answers
65 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 ...
1
vote
1answer
72 views

Difference between photo electron spectrum and photoelectron angular distribution

I am trying to learn the Photoelectron velocity map imaging. While I was going through the article "Chem. Soc. Rev., 2009,38,2169-2177", it is said that the "photoelectron spectrum reflects the energy ...
1
vote
1answer
86 views

Molecular spectroscopy for atomic spectroscopers

My experience is with atomic spectroscopy of alkali atoms, I've recently been asked by a friend to help with some advice on analyzing molecular spectrophotometry data in the context of molecular ...
1
vote
1answer
170 views

Rutherford Scattering Spectra

I am using SimNRA to simulate the classical Rutherford Scattering. Playing around with it, I came across some spectra that I cannot explain... First of all, if someone plots the spectrum of ...
1
vote
3answers
1k views

Franck Condon Principle and Born Oppenheimer approximation

My question here is purely fundamental. I am confused with the concept in Franck Condon (FC) principle and Born Oppenheimer (BO) approximation. The FC principle is in accordance with the BO ...
1
vote
1answer
114 views

Dividing two star spectra

I am doing some work that involves dividing two stellar spectra from the same star. Those stellar spectra are constructed by summing random samples of multiple spectra from the same star to improve ...
1
vote
2answers
303 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 ...
1
vote
0answers
14 views

Vibrational quantum notation

Reading articles on spectroscopy I often see this notation: 30001 <- 01101, 00011 <- 00001 in context of molecular ...
1
vote
1answer
49 views

Total magnetic moment in an atom

I have a doubt regarding the calculation of total angular momentum of electron in an atom.Which is the right way to do it? Method 1: Total magnetic moment $$ \begin{align} \vec{\mu_J} &= ...
1
vote
1answer
27 views

How does change of pressure affect molecular rovibrational bands position and width?

Lets say I have $CO_2$ gas chamber with pressure $P_0$. How do rotation-vibrational transition bands alter when I change pressure P? Do they shift or not and why?
1
vote
0answers
10 views

Dielectric resonance spectroscopy of thin and thick film

How does the technique vary for dielectric resonance spectroscopy for thin film of ~ 3 micrometer and a relatively thick film of 100 micrometer?
1
vote
0answers
33 views

What are the current size limitations of NIR spectroscopes? [closed]

So few days ago I came across this new tool for smart phones http://www.consumerphysics.com/myscio/. It says it uses NIR spectroscopy, which I don't know lot about. My question is: Is it possible for ...
1
vote
1answer
97 views

Wigner Threshold law in Photodetachment and Photoionization

I am writing this question here because I have a problem in understanding the Wigner Threshold law in Photodetachment and Photoionization. The Wigner Threshold Law is given by: $\sigma$=$E^{L+1/2}$. ...
1
vote
0answers
55 views

Why does inelastic X-ray scattering probe the longitudinal dielectric function as opposed to the transverse dielectric function?

Light is a transverse wave. Therefore, light in the optical range (i.e. visible light) couples to transverse collective excitations of a material when measuring the optical conductivity for instance. ...
1
vote
0answers
12 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 ...
1
vote
1answer
89 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 ...
1
vote
1answer
26 views

Equivalent temperature: laser and cell containing Rb

What's the meaning of "equivalent temperature" related to a cell containing rubidium and crossed by laser?
1
vote
1answer
140 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 ...
1
vote
0answers
124 views

Intensive radiative heat transfer in very hot gas ( >5000K, gas core nuclear reactor related )

The question: At temperatures above ~5000K are not stable any solid or liquid materials or even more complex molecules (such as fullerenes and Polycyclic aromatic hydrocarbons) which emit/absorb ...
1
vote
0answers
128 views

Total angular momentum in multielectron atoms

I have some confusion about orbitals in multielectron atoms. Let's say we consider an atom (Lithium, for example, $1s^2\, 2p^1$) and that the state of the last electron is [n=2, l=1, ml=0, s=1/2, ...
1
vote
1answer
453 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 ...