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

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118 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 ...
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105 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 ...
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2answers
191 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 ...
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128 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 ...
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21 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 ...
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55 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 ...
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339 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.
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371 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 ...
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98 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 ...
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27 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 ...
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3answers
97 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 ...
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76 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 ...
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37 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 ...
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52 views

For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we get absorption lines?

For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we see absorption lines? Similarly, why do we see emission lines if the planet is hot on the ...
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541 views

What is decay associated spectra?

What is decay associated spectra? Suppose we measure the fluorescence intensity over different wavelengths and over time, we get: $$I(\lambda,t) = \sum_i^n \alpha_i(\lambda) ...
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82 views

4 element super conductor without oxygen and iron

I am trying to find a list with super conductors. In particular I am searching for a superconductor, that consists of 4 elements none of which is Oxygen. The reason I rejected Oxygen, is because(from ...
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228 views

Diffraction Grating in spectrophotometer

In terms of spectrophotometer, we need to make the light monochromatic before passing it to sample. For that, we use diffraction grating. From the research, I found out that the grating reflects light ...
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258 views

Thermionic emission and delayed emission

I want to understand the concepts behind the thermionic emission. In thermionic emission, the energy randomization occurs and the energy may be split to electronic or roto-vibrational states. If this ...
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1answer
19 views

Gamma Spectroscopy - Why no Intensity level for Neutron Capture?

I'm undertaking a bit of work looking at a Background Gamma Spectrum. On the spectrum, I have a clear, tall line at 834 KeV. I have a PDF file of a table of Gamma Spectra (ordered in energy) from ...
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31 views

Asymmetric photoluminescence spectra

Why do photoluminescence spectra have asymmetric lineshapes as those here http://www.scielo.br/img/revistas/bjp/v37n4/a04fig01.gif or here: ...
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40 views

What is the reason that EXAFS are done with monochromatic x-ray light?

Why is the light incident on the samples in EXAFS experiments monochromatic? What would happen if a broad bandwidth hits a grating and then all the diffraction spectrum goes through the sample and is ...
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1answer
172 views

What's the difference between NMR and EPR?

Both NMR and EPR describe the response of magnetic spin to external field. When collecting data, how do you know you're looking at nucleus spin flip or electron spin flip? In other words, since every ...
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22 views

Spectroscopy - Absorption lines

Let's say we run a light source (a strong torch) with full spectrum light through a big, transparent, glass box filled with neon. Will we be able to see any Fraunhofer lines on the spectral analysis ...
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49 views

How are different wavelength components collected by the same detector in a spectrometer?

Let's think, we have a detector array (128x1 and each CMOS detector responds 400 to 1000 nm TSL1401CL that way, each detector has 4.6875 nm interval). Then, basically in a spectrometer a prism reflect ...
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3answers
191 views

Spectrometer vs. Spectrophotometer

I have been researching about the difference of a spectrometer and a spectrophotometer. They both sound the same. What is the difference?
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139 views

What is harmonic and fundamental bands in IR spectroscopy?

What is harmonic and fundamental bands in IR spectroscopy? I'm trying to find exact definitions. I guess that fundamental is $1\leftarrow 0$ transition (the most intense and energetic) and harmonic ...
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41 views

What is “Lifetime Intensity” in photoluminescence?

I'm reading an article "Surface plasmon enhanced Förster resonance energy transfer between the CdTe quantum dots". Link The reasearchers are writing about increase in "lifetime intensity" and even ...
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75 views

Nuclear explosion wavelength data

I am looking for data source (or chart) of spectral data that is being emitted on detonation of nuclear or thermonuclear explosion. Reason I am looking is to see if this data has specific signature ...
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201 views

Non Adiabatic Coupling Term in Born Oppenheimer Approximation

I am attaching a section from a text book (Conical Intersections Electronic Structure, dynamics and spectroscopy: David R Yarkony & Horst Koppel). Here I am not understanding the so called 'Non ...
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1answer
188 views

Where I could find values for rare earth metalls levels diagramm (Dieke diagram)?

The Dieke diagrams like this: could be easily found in internet. But it is impossible to determine from where they get values initially, everyone is making cross-links. I'm especially interested ...
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2k views

How to calculate the total angular momentum (J) values

How can I calculate the values of $J$ (total angular momentum) for a particular term, for instance, ${}^3P$?
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1answer
46 views

Is the temperature different and or salinity different can lead to different colour of the water bodies?

I had skimming on an article about Thermocline and Halocline. How can two seas not mix? However, I am still curious on: Why the effect of Thermocline and Halocline are distinguishable based on ...
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1answer
435 views

UV-VIS spectrometer on Solids

I ran an experiment using translucent single crystal solids. I modified the solids along the way using different chemical/temperature environments. After every stage, I ran the samples through a ...
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385 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.
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388 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 ...
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18 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 ...
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1answer
15 views

How to get a better handle on Spectral Irradiance conversion?

I'm using a computer program to simulate a lightsource. I can feed my own spectral irradiance values into the program to simulate color rendering accuracy. The program takes values in electron volt ...
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1answer
21 views

Help reading power spectrum graphs?

How would I go about figuring out how long a source was measured when given a graph of the power spectrum? From notes I'm following, they just state the total observation time as being roughly ...
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19 views

Can near-infrared spectroscopy distinguish between various metals?

Can near-infrared spectroscopy be used to distinguish metals from another? If not, why not?
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25 views

Estimation of source irradiance given the spectral sensitivity of the instrument and spectrum of the source

I am trying to measure the irradiance of a UV source, but the available instrument has a different sensitivity. Suppose the black line corresponds to the spectral sensitivity of the instrument ...
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27 views

Deconvoluting Raman spectras from different wavelengths

I am using a laser source that is wider than typical laser source for Raman spectroscopy. This mean that the full width at half maximum (FWHM) of the laser is about 5-10 nm, compared to the normal 1-3 ...
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11 views

Hyperfine structure interval rule only obeyed approximately?

The hyperfine interaction is given by $\Delta E = A \langle I \cdot J \rangle = \frac{A}{2}\left[ F(F+1) - I(I+1) - J(J+1) \right]$. The interval rule is given by: $$ \frac{\Delta E_{F,F-1}}{\Delta ...
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19 views

Does water absorb microwaves above of beneath its relaxation frequency

I am a bit confused about the concept of relaxation frequency. In my course text we derived a model with the help of Newton's law to describe the movement of polar molecules in an electromagnetic ...
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9 views

Velocity Selective Coherent Population Trapping and recoil limit on temperature

I have read that it is possible to go under recoil temperature limit using VSCPT (Velocity Selective Coherent Population Trapping) and that this method is based on atoms trapping in quantum state in ...
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17 views

Doppler and recoil limit on temperature

I havent't understood the causes of Doppler limit and recoil limit. I have found on the net different observations about them ("Doppler limit is due to the fact that the atom can't have a smaller ...
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1answer
37 views

Optical spectrometer

I am new on optical spectrometer, my particular interest is the spectrometer in which the deflection is produced by diffraction in a diffraction grating. But I can not find a good schematic and the ...
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25 views

Reflectance spectrum and Real Refractive Index Relation

I have taken in the laboratory mesurment of the Reflectance spectrum of a material and via mathematica calculated the phase for Kramers-Kronig Relations,and finnaly i calculated from it the real part ...
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19 views

Does the EXAFS oscillations occur when ultrashort x-ray pulse is used? Electron with a 50eV kinetic energy will travel in 0.1fs 4.2 Angstroms

In X-ray extended absorption spectroscopy (EXAF) an electron is excited by an x-ray photon into the continuum, the outgoing electron wave interferes with the scattered electron wave from the ...
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33 views

Why does the spectrum for deuterium show a weak line at H-alpha?

I was wondering why the spectrum for deuterium shows a weak line at H-alpha, the first line in the hydrogen spectrum.
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52 views

Bandwidth-Pulse Duration Relationship

Assuming Gaussian pulse, the relationship between pulse duration and bandwidth is given by: $$\Delta \nu \cdot \tau \geq 0.441$$ If the rms bandwidth and rms pulse duration are used, then the ...