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

learn more… | top users | synonyms

1
vote
0answers
43 views

Quantum beats and Quantum mechanical side of photosynthesis

I have two questions. One concerning quantum beats alone, another - process of photosynthesis. I am very well aware that there is strong evidence suggesting that mechanism that leads light through, ...
1
vote
0answers
27 views

Can one measure experimentally the average distance between the two electrons in the excited state of helium in the singlet versus triplet states?

$\frac{1}{\lvert\ \vec(r_{1})-\vec(r_{2})\rvert}$ is a hermitian operator so I am supposing there could potentially be an observable with this which might be experimentally measured. We can measure ...
1
vote
1answer
10 views

Sound range and depth it travells whe it hits sound

I know most people hear from 20hz to 20000hz and about the absorption spectrum of water absorption spectrum of water link but how deep does sound travel when it hits the skin and which range of ...
1
vote
0answers
13 views

Diffusion of magnetization (NMR)

In the context of MRI I'm trying to understand the mechanisms of magnetization diffusion. Consider a sample that is magnetized by an external magnetic field. We have displacement of magnetic moment ...
1
vote
0answers
18 views

Modelling populations of GE isotopes

I asked a question similar to this here: What combination of stable GE isotopes make up the germanium in a Ge(Li) spectrometer And got some very good answers. This question is instead based on the ...
1
vote
0answers
38 views

Coincidence summing in gamma spectrum

Question on coincidence summing here. I've been reading about the coincidence summing effect when a radionuclide has two energy levels that decay to another state in rapid succession. There is also ...
1
vote
0answers
65 views

Activation energy of luminescence

Assuming that activation energy is constant for some range of temperature, it can be determined from the slope of the plot: $$\ln{I}=A-\frac {E_a}{k_bT}$$ where $I$ - intensity , $E_a$ - activation ...
1
vote
0answers
47 views

Using stellar spectroscopy to measure stellar parameters, why is it log g?

Stellar spectroscopy can in principle measure the stellar surface gravity, radii, effective temperature, and stellar rotation. Why is it that surface gravity g is ...
1
vote
0answers
103 views

UV absorption decrease with an increase in concentration

I am working on a project measuring the absorbance of a solution which contains surfactant and hard brine. The solution has a constant concentration of surfactant and varying concentration of hard ...
1
vote
0answers
59 views

What does 'easily reversed' mean in the NIST spectral database? [closed]

Cross posted to http://engineering.stackexchange.com/q/3303/ I'm trying to do some processing of optical emission spectra from sputtering plasmas, and am confused by what NIST means by 'easily ...
1
vote
0answers
33 views

PM-IRRAS Equidistant Fringes in Spectrum

What is the cause, and best method to prevent / minimize, fringes in one's FTIR (PM-IRRAS) spectrum on samples deposited on a thin metal film? The fringes look as though they are spaced out by a ...
1
vote
0answers
63 views

Can anybody explain about phase shift and phase spectrum terms in case of multidimensional signal?

I know about phase of a 1D signal, but when I move into higher dimensions like 2D or 3D etc, it becomes headache to grasp the concept. What do the terms "phase shift" and "phase spectrum" mean in ...
1
vote
0answers
49 views

Why graphene's substrate is important

I just have some feelings that somehow it is important what specific subtrate is used to grow graphene monolayer on. Some substrates are better, another ones are not so good. But I cannot completely ...
1
vote
1answer
57 views

How to convert the molar attenuation coefficient, ie. molar absorptivity, to heat capacity?

In spectroscopy techniques, such as infrared spectroscopy, light of a certain wavelength is absorbed. I see parallels to the concept of heat capacity, i.e. the heat necessary to change the temperature ...
1
vote
0answers
90 views

Angle-resolved photoemission spectral (ARPES) function from band Hamiltonian

I am trying to derive spectral function for a band Hamiltonian. I am using http://arxiv.org/abs/cond-mat/0306084 as a prototype reference. I do not understand how the coherence factors $u_k$ and $v_k$ ...
1
vote
0answers
66 views

Rotational Spectrum of a Diatomic Molecule

The rotational energy levels of a diatomic molecule are given by $$E_l=\frac{\hbar^2}{2I}l(l+1)$$ where $l$ is an integer. If the molecule is a dipole it can emit or absorb electromagnetic radiation ...
1
vote
1answer
57 views

Is there a correct yet more compact way to write these equations?

I've got the following equation which denotes the total absorbance $A$ as determined by the sum of the absorbances of individual molecules: \begin{equation} A(\nu,c_{1},...,c_{n}) = \sum_{mol=1}^{n} ...
1
vote
0answers
79 views

What's the difference between “spectromicroscopy” and “microspectroscopy”? [duplicate]

Both definitions that I found are rather vague. (Related question: What's the difference between microscopy and spectroscopy?)
1
vote
0answers
19 views

Explain materials with 4 fold symmetry having same reflectance when shone with LCP and RCP

This is my first post here. I am currently reading "Optical planar chiral metamaterial designs for strong circular dichroism and polarization rotation" by Do-Hoon Kwon, Pingjuan L. Werner, and ...
1
vote
1answer
39 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
18 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
43 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
0answers
84 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
24 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
32 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
249 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
202 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
198 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
0answers
69 views

How to absorb a characteristic line in a spectrum

I have an x-ray tube. When I see the spectrum, I notice the characteristic lines of the anode. What do I have to do if I want to absorb a characteristic line? I have thought that I can add a filter. ...
1
vote
1answer
125 views

Thermionic emission, delayed emission and predissociation

In molecular photodissociation, the thermionic emission, delayed emission and predissociation are the same? Otherwise, what is the difference between them? My question is not about the solids, but I ...
1
vote
0answers
111 views

Correlation function in relaxation in NMR

I am new in this community, I am from a chemistry background. I want to know a detailed solution of a density matrix for a singlet state using the concept of spin lattice relaxation in NMR. I will ...
1
vote
2answers
201 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 ...
1
vote
0answers
129 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 ...
0
votes
2answers
71 views

Gamma spectroscopy - Do annihilation photons produce a backscatter peak?

Below is a diagram of part of a structure which I find in a gamma spectrum taken from a hall in which a neutron source is undergoing spallation. The structure which I'm interested in can be seen ...
0
votes
2answers
28 views

How to measure the spectra of the stars

I recently made a mini spectrometer using a CD. I have used that to measure the spectrum of the Sun, moon and various artificial light sources. My question is how can I use it or modify it to measure ...
0
votes
1answer
117 views

Hydrogen Spectra using Hydrogen Gas Discharge Tube

I am doing an experiment for my lab work which include determination of value of Rydberg Constant using method of Interpolation. For this we first plot calibration curve for various wavalengths ...
0
votes
2answers
68 views

Photon yield of NaI

We have to calculate the photon yield of the scintillator NaI. We have measured his pulse height spectrum but we have no idea how to solve this problem. Can someone explain it? The source that we used ...
0
votes
1answer
412 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.
0
votes
1answer
24 views

Can we determine the surface temperature of stars other than the sun by using the black body radiation theory?

It is well known that the surface temperature of the sun can be determined by fitting the solar spectrum to the black body radiation spectrum. Is this scheme feasible for other stars? Possibly the ...
0
votes
1answer
21 views

What is the meaning of the magnitudes on the axes of this spectrum?

I'm taking a course on radiation physics and I've been given an spectrum by my professor (concretely it is a spectrum of $\left.^{22} Na \right.$). This is the first time that I come across this kind ...
0
votes
1answer
76 views

I don't understand the spectrum of elements e.g. hydrogen spectrum [closed]

Quote from my textbook The hydrogen spectrum has spectral lines which correspond to transitions of the electron between energy levels. This statement implies that hydrogen has multiple electron ...
0
votes
3answers
166 views

Having trouble understanding spectral lines

In my notes I wrote that Rutherford's model of the atom could not explain spectral lines, because that is what my textbook says. I'm not really sure about the details of spectral lines though. I know ...
0
votes
1answer
624 views

Precision measurements on sodium doublet wavelength?

I'm currently searching for a good and reliable source where precision measurements on the wavelength of the so called sodium doublet ($D_1$ and $D_2$ lines) at approximately 589.0 nm and 589.6 nm are ...
0
votes
1answer
114 views

How to measure distances to stars by means of spectroscopic parallaxes?

How to measure distances to stars by means of spectroscopic parallaxes on practice? What is the accuracy of measuring distances using this method compared with distances based on HIPPARCOS ...
0
votes
1answer
9 views

The $^1S_0 \rightarrow ^3P_0$ transition in O III

Checking out NIST data, I cannot seem to find any data about a $p^2$ valence atom, such as O III, for the $^1S_0 \rightarrow ^3P_0$ transition. Obviously it isn't a electric or magnetic dipole allowed ...
0
votes
1answer
28 views

Where can I find the Auger emission spectra of the most common chemical elements?

I am looking for an online resource where I can find the Auger emission spectra of (most common) chemical elements, i need them for AES (Auger Emission Spectroscopy). Thank you.
0
votes
1answer
42 views

FWHM of different spectra and separation in fine structure

I'm doing some research on spectroscopy and there are some phenomena I can't explain (only a second year physics student). I took some spectra of neon in the 659.89529 nm and then of hydrogen at ...
0
votes
1answer
118 views

Detecting molecules in space?

http://www.forbes.com/sites/alexknapp/2012/02/24/nasa-detects-solid-buckyballs-in-space/ I refer to the above article, which mentions that buckyballs "far smaller than the width of a hair" were ...
0
votes
2answers
127 views

Why doesn't the color of an object change when signal of different frequency impinge upon it?

Correct me if I'm wrong but I've always thought that the color that an object has is due to the oscillation of the atoms that makes up the material of that object. When white light is shine upon an ...
0
votes
1answer
45 views

Hydrogen Spectra [closed]

I am talking about hydrogen spectral lines such as Lyman, Balmer etc. In order to make those spectral lines series more than one electron are needed to jump from higher orbits to lower orbit. But ...