Spectroscopy is the study of the interactions between matter and radiated energy. Experimentally, the results are returned as a function of wavelength versus amplitude (intensity), where the spectral lines represent the resonance frequency of the sample.

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Near IR spectroscopy vs. IR spectroscopy

I am a backer of this Kickstarter: SCiO Near IR Spectroscopy Here is a link to their technology: SCiO Technology Question: How short of full IR spectroscopy do you think this device is? I have asked ...
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What are scattering losses?

In UV spectroscopy, when a beam of light is shone into solution, what is scattering loss during this process?
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several coefficient differences in UV-vis Spectroscopy

Does anyone know what is scattering coefficient, absorption coefficient and extinction coefficient, and how to separate them experimentally?
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37 views

difference between absorption spectroscopy and extinction spectroscopy

can anyone tell me the difference between absorption spectroscopy and extinction spectroscopy in terms of experiment? and how to get extinction spectroscopy, how to get absorption spectroscopy? Thank ...
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Why do we say approximation in the dipole approximation in spectroscopy?

In the dipole approximation the following relation holds: $\hat{V}=-\hat{\mu}\overrightarrow{E}$. When we say "approximation" I guess we want to point out, we are dealing with linear spectroscopy, ...
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How Do I Identify What Impurities Are in My Product?

I am writing a lab report for Organic Chemistry about a multi-step synthesis that we conducted. While our product has the proper melting point, its IR spectrum has peaks not present in the respective ...
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Are there any free phosphorus-31 NMR spectral libraries?

I know that there are some sites like Sigma Aldrich and AIST for $\ce{^1H}$ NMR and $\ce{^13C}$ NMR, but was wondering if there were any free sites to compare $\ce{^31P}$ NMR spectra?
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In spectroscopy, is it possible for the sample to be excited multiple times?

The context of my question is rotational spectroscopy (using microwave radiation), where there is the $J = \pm 1$ selection rule. The way I understand spectroscopy is that the sample is irradiated ...
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264 views

Why is wavenumber used in IR spectroscopy rather than wavelength?

In IR spectroscopy, the $x$-axis is used to represent wavenumber, in $\mathrm{cm^{-1}}$. Why is wavelength, equal to $1/\lambda$, used in place of wavelength, which is simply $\lambda$? Sources I’ve ...
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IR fluorescent material for outdoor use

I am experimenting with IR video cameras. They have a broad sensitivity peak at 940 nm. There is a filter blocking 750 nm and shorter in front of the sensor. I am looking for an IR fluorescent ...
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23 views

Can one figure out an optical absorption spectrum from EPR data?

I'm wondering if it's worthwhile for me as an optical spectroscopist to read up a bit on EPR. Do EPR signals reveal where, in terms of wavelength, features in the optical spectrum can be expected to ...
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154 views

Bohr's model of atom

"the most remarkable success of the Bohr's theory is that it provides a satisfactory explanation for the line spectrum of hydrogen." But what is the problem with line spectrum of hydrogen which ...
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Are the bonding orbitals in methane equivalent - photoelectron spectrum

The low energy portion (the part dealing with the $\ce{2s}$ and $\ce{2p}$ electrons) of the photoelectron (PE) spectrum of methane is reproduced below. (image source) The reaction being examined ...
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Explaining the photoelecton spectrum of krypton

The photoelectron spectrum of krypton is shown below. (where the x-axis is in electron volts (eV))\ Since both the $3p$ and $3d$ shells are more than half full, based on Hund's rules the ...
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Possible ionization and fragmentation of chemicals

Is there any generic method where I can know/calculate/generate the possible ionization and fragmentation of a specific chemical, for example, hydrogen chloride and water. Replies are greatly ...
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22 views

Identifying phycobiliprotein based on wavelength

I have the absorption spectrum of a specific phycobiliprotein. Its maximum wavelength is 620.6 (nm),this is the only data I have. How can I know what type of phycobiliprotein it is?
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35 views

Choosing the instrumental techniques for chemical analysis [closed]

Since every technique has its goods and its bads characteristics, it's a bit hard for me to choose between them to determine specific elements, methods such as UV-VIS spectroscopy, IR spectroscopy, ...
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26 views

How photoluminescence (PL) spectroscopy works

Photoluminescence (PL) spectroscopy is used to find the energy levels in a compound but how does PL spectroscopy works? After exciting a material with a particular wavelength whether PL machine looks ...
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42 views

Carbonyl group Conjugation and IR spectroscopy

Here's the problem... Three isomeric structures with formula $\ce{C10H8O2}$ are shown: I understand that conjugation in the systems will affect the carbonyl stretching ...
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Qualitative spectrographic analysis

In order to identify the presence of a specific element, one must identify at least three ultimate lines of that element in the specter. Those lines are the ones with the highest intensity. I ...
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Atomic emission spectroscopy

There is a sentence in my book I don't understand : Every atom or ion, which has one valence electron, will have double lines in the atomic emission spectrum. For example $\ce{Na}$ will produce lines ...
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35 views

The relation between magnetic resonance spectroscopy and the causes and effects of electromagnetic induction

This is a more physics question, but I need specific chemical knowledge and opinion. Using electric charges to produce current, it was found that an electric charge and magnetic dipoles are related ...
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Has a triplett sigma state of a diatomic molecule a spin orbit coupling?

I know that states with spin S=0 in a diatomic molecule have no spin orbit coupling, independent on the value of the projection of the total electronic angular momentum. I expect the same is true if ...
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Relevance and Determination of the reflection symmetry +/- in Spectroscopy?

If there are two electrons located in a shell (which contains two subshells) the molecule can either have a singlet state (if both electron are in the same subshell; because of the Pauli principle) or ...
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How to interpret orbital transition in TDDFT?

Consider the following TDDFT run with GAMESS: ...
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Why Acetone does not behave like its computational values?

I am trying to simulate the excitation state of acetone. I ran TDDFT for it both in gas phase and solvated state in water (both implicit and explicit water). The experimental data say that acetone ...
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Determination of mercury in AAS

Its known that the only method to determine mercury in atomic absorbtion spectroscopy is the cold vapor method. What is the reason that mercury can't be determined with other methods, such as flame, ...
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How to confirm the type of bonding taking place between two substances?

For example ink on paper: how can I confirm that the bonding is van der Waals and not covalent? Similarly, the same question can be asked about other interaction such as hydrogen bonding, ionic ...
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Is a microwave oven dangerous? [closed]

If we take a look at the electromagnetic specter, microwave wavelength is higher than infrared, which means its energy is very small. To break chemical bonds, the energy required is 100-1000 kJ/mol, ...
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Why might the ratio between two Q-band peaks in ZnTPP decrease with increasing temperature?

In ZnTPP (Zinc tetraphenylporphyrin), there are two Q-band emission peaks. When I run steady state emission measurements at different temperatures, the ratio of their respective peak intensities ...
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Is it possible to predict the lines in the atomic emission spectrum of Na?

The atomic emission spectrum for sodium ($\ce{Na}$) is completely dominated by a line in the range of yellow, about $590~\mathrm{nm}$ (to be more precise, it's a doublet). Here is how it looks like: ...
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Rotational degrees of freedom (3N-5 and 3N-6)

In spectroscopy we described the electric energy with the approximative separability of internal motions as: \begin{equation} E=E_e+E_v+E_r+E_{ns} \end{equation} (energies: electronic, vibratory, ...
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Wavelength extention in AAS

Theoreticly, the width of the spectral line in AAS (atomic absorbtion spectroscopy) is 10^-5, but in fact there happens an extention of it and it becomes 0.002-0.005. There are some factors which ...
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116 views

UV/Vis spectroscopy transition reference

There are mainly fundamental transitions happening during excitation and UV/Vis spectroscopy (as n- > σ* ,π->π* ,n- > π ,..). I am looking for a good reference that shows these transitions for ...
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Auxochrome groups

Functional groups like $\ce{OH}$, $\ce{NH2}$, attached to nonsaturated compounds (chromophores) are called auxochromes. These groups tend to shift the wavelength to the infra-red area which is called ...
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Reference for UV/Vis Spectroscopic Data request

I am looking for a complete reference of UV/Vis spectroscopic data for organic materials ( mostly interested in λmax ) . I have the CRC handbook but it only has data about some organic solvents in ...
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What are the spectroscopic signatures that differentiate triple state water from water at 1 atm?

According to the Wikipedia article Triple point of water, the triple point of water occurs at The single combination of pressure and temperature at which liquid water, solid ice, and water vapor ...
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Infrared spectroscopy of substances on a OHP film

How can we record a IR spectrum of a substance coated on a Over Head Projector (OHP) sheet? instrument has both transmission and ATR modes. IR spectrum is to be recorded for both the OHP sheet as well ...
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Why do electronegative heteroatoms increase C=O stretching frequency (bond strength)

Why does a more electronegative heteroatom (i.e. $\ce{Cl}$ or $\ce{O}$) increase the stretching frequency of a carbonyl? I'd suspect it's that they donate their lone pairs and we end up with a ...
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Spectral Peak-Picking in MS Excel

I'm working often with spectral data of various gases, and the bulk of the data analysis is assigning the peaks with maximum signal (y-axis) to frequency (x-axis). Often we have several thousand data ...
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1answer
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What is this reference material in spectrophotometry?

First, I should say I never have done any spectroscopies and I am just reading about it. As far as I know, UV-Vis spectrophotometer has 2 beam samples: sample and reference. The sample has very ...
2
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1answer
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What happens to chemical shifts of protons close to aromatic systems in ¹H-NMR?

I have two questions regarding chemical shifts on aromatic systems. First, what does being near an aromatic system do to protons? If we look at the spectra of 1-napthalenemethanol and then ...
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Spectral reflectance identification of types of iron rust

Based on the Wikipedia page about rust, there are red and green types of rust that occur on iron. Red rust is the reaction with oxygen and water and the green with chlorine (in oxygen poor ...
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How to calculate vibrational spectra of organic molecules?

I watched a ted talk (Luca Turin: The science of scent) and was wondering if anyone had any examples of how to calculate vibrational spectra of molecules (used as fragrances)? Would love to figure ...
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How to find pKa given absorbances and pH [closed]

If the absorbance of one of the buffer solutions (pH = 4.623) was 0.319 and the absorbance of the basic solution was 0.625, what is the $\mathrm{p}K_\mathrm{a}$ of the indicator? Include activity ...
3
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Amount of substance of a molecule in a solute the same as amount of substance of constituent elements?

I’ve done absolutely no chemistry since high school. Now, 16 years later, I’ve been asked to look at some chemical analyses and I’m having trouble! Context: I’ve got a series of spectroscopy ...
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70 views

Do core electrons in bulk material have discrete energy levels or continuous energy band?

The energy band of valence electrons gets smaller and smaller when the lattice (bulk) atoms are more and more separated from each other, until discrete energy levels are formed, due to the isolation ...
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In infrared spectroscopy, why is there no C=C reading for E alkenes?

For the (E)-2-pentene, there was no C=C reading, about 1600. For the (Z)-2-pentene, there is a C=C. Why is there a reading on the Z but not on the E?
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Finding identities of diatomics from Spectroscopy and Mass Spec Data

Let's say I have a sample of 2 (assumingly different) diatomics A and B. Through Spectroscopy I found the data below: For molecule A: $$B ̃=2.17690\space cm^{−1}$$ $$D ̃=4.79000×10^{-5} cm^{−1}$$ ...
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Lambert Beer's law deviations

Can somebody explain as concrete as possible, how the change of temperature and the change of pH leads to deviations of this law?