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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Could someone please explain the difference between m/z and m/e in mass spectroscopy

The definition: The abbreviation m/z is used to denote the dimensionless quantity formed by dividing the mass number of an ion by its charge number. It has long been called the mass-to-charge ratio ...
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28 views

Difference between an absorbance, emission, and excitation spectrum for uv-visible spectroscopy

The exam paper answer is 500, because we need the wavelength of "maximum absorbance." But this graph shows two curves, and the absorbance curve is omitted. But what is the difference between an ...
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29 views

How to calculate m/e value for the base peak in mass spectroscopy?

My working out: Propan-1-ol : CH3CH2CH2OH This can be broken up into: CH3 + CH2CH2OH CH3CH2 + CH2OH CH3CH2CH2 + OH Base peak = most abundant fragment formed (highest peak) How do i know which ...
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29 views

UV-Visible Spectroscopy in the analysis of sodium chloride in potato chips

Here is the question and answer out of an exam paper: Firstly, I thought UV-Visible can also use radiation in the visible spectrum. Also when analyzing sodium chloride (a molecule), then UV-Visible ...
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36 views

1H-NMR and deducing structures

here is the data booklet we must refer too: Here is the exam paper solution: I dont understand how they conclude this. Peak areas and the chemical shifts seem to be different for me. For ...
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Fluorescence Spectra, emission spectrum

What exactly does the excitation spectrum tell us about a sample in Florescence Spectroscopy, what information does it tell us? I know that we will get an output of concentration vs intensity but ...
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21 views

If absorbance is 0, what is the equilibrium constant?

If the absorbance of something is 0, what is the equilibrium constant? In a reaction, the absorbance is 0, so the concentration of the product is 0. The concentration of one of the reactants is also ...
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149 views

Why is filter paper fluorescent?

Typical filter paper used in chemistry lab (e.g. Whatman #1) exhibits autofluorescence in near UV with excitation maximum at 365 nm and emission maximum at 440 nm. It was reported in literature[1] ...
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38 views

Alcohol irregularities in Hydrogen NMR

We've started learning about NMR in my ochem class and my instructor told us that in Hydrogen NMR an alcohol can have a fairly wide range of possible values - usually from about 2 to 5. He said that ...
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56 views

Help with understanding term symbols

I think that I understand most of the parts of the symbol shown for ground state oxygen However, I was hoping that someone could tell me what exactly the negative superscript sign means? And how do ...
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67 views

Looking for raw interferogram data / raw FID data from FT-IR / FT-NIR / FT-NMR

I'm trying to get my hands on some raw interferogram data / raw FID data from an FT-IR / FT-NIR / FT-NMR so I can run some tests using FFT with it (it needs to be real data). Here's a picture below of ...
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How to get defect-energy level diagram from PL data

I am reading this article Phys. Chem. Chem. Phys. , 2011, 13, 14902-14905 and seen that the authors have drawn a image of defect level using PL data Can you explain me how this diagram can be drawn ...
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70 views

Does my data show quadratic regression in a calibration curve?

This data was taken for my science fair project, and I would like to know the relationship between spectrophotometer absorbance and cell density (taken manually) of algae after a toxicity test. The ...
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1answer
88 views

What is the approximate lifetime of an $S_N2$ transition state complex?

Imagine some $S_N2$ reaction involving an aliphatic $sp^3$ carbon with a halide leaving group (e.g. Iodide or Bromide). Given the rise of femtosecond spectroscopy (e.g. using a mode-locked ...
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1answer
103 views

Why does the excitation and emission spectrum of a fluorescent molecule have overlap?

Question is rather self-explanatory. Came up during a lecture without a concrete answer. I understand that the differences in emission wavelengths is due to relaxation to the lowest energy level of ...
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32 views

Red glow in the dark pigments

I want to do some spectrometry experiments with glow in the dark paints. The red paints I've read product details for all seem to require a uv light to charge. Are there any red glow in the dark ...
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1answer
49 views

Are there any molecules with the same spectrum?

Are there any two distinct types of atom or molecule that have identical emission or absorption spectra?
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46 views

Changes in defects in a material due to heat treatment

Currently i am doing some research on optical properties of a oxide material and for that purpose i have done some photoluminescence study on it. Because this is an ongoing research i cant divulge ...
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167 views

Understanding moseley's law from the rydberg-type equation?

To explain the characteristic X-ray emission peaks for various elemental targets, a formula was developed which was similar in construct to the rydberg equation for H-atom as derived by the ...
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148 views

How to use IR spectroscopy to determine structure of molecule

A molecule $\ce{XY2}$ is known to be linear, but it is not clear whether it is Y-X-Y or X-Y-Y. How would you use IR spectroscopy to determine its structure?
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361 views

Effect of dopant size on XRD peak shift

If we add an impurity atom (doping) to the crystalline struture of another material and take the XRD of the doped material what kind of peak shift can we expect. For the better description of my ...
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1answer
2k views

What is the principle of diffuse reflectance spectroscopy behind band gap measurement?

As the title suggest can you explain how DRS can be used for finding band gap of a material. Below is an DRS output result: From the figure we can see that at about 465 nm the reflectance drops ...
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72 views

NMR Spectroscopy - simplification

I understand the fundamental principles of NMR spectroscopy, however what I fail to do is apply my understanding in order to form a structure of the molecule in question. My difficulties are the ...
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210 views

Which are the differences between resonance Raman and fluorescence?

If the fluorescence is the re-emitting of a photon with a larger wavelenght due to the transition from a higher energy state to a lower energy state the case of resonance Raman (where there aren't any ...
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Colors of soap, Dodecanol, and chlorosulfonic acid

I was wondering if anyone had any insight as to why the reaction of chlorosulfonic acid (colorless) and 1-dodecanol (colorless) produces a deep dark red colored solution? The reaction should give ...
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176 views

Bond of interest

What does it mean for our bond of interest if we have low bond length and high frequency? Trying to make this connection but am not understanding. If anyone could explain it intuitively, that would be ...
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83 views

Do chemical compounds have spectral lines, or only elements?

I know that elements (ex. Ag) have spectral/emission/absorption lines, but do chemical compounds (ex. NaCl) have spectral lines as well? Ones that when seen you can tell that that compound (NaCl) is ...
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135 views

Can dust or fingerprints interfere in ultra-violet spectroscopy

My question pertains generally to any form of spectroscopy, but I'll focus on UV spectroscopy. I am trying to get information on carrying out spectroscopy, but most of it is theoretical. Wikipedia is ...
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63 views

How did Scientists Capture The First Images of Molecules Before and After Reaction?

"Using a state-of-the-art atomic force microscope, the scientists have taken the first atom-by-atom pictures, including images of the chemical bonds between atoms, clearly depicting how a molecule's ...
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454 views

How do I know if concentration of Ammonia affected my absorbency measurements?

This is for determination of copper in a penny Lab. After making standard solutions we made a solution with a penny, dissolving it in nitric acid and adding ammonium hydroxide to form a more ...
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239 views

Wavelength of light

how do you calculate the wavelength of light? For chemsitry lab, we calibrated the scale reading of Hg, for example, to be 4.91 cm which is violet and the given wavelength says 436. For Hg, it says ...
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93 views

What does the signals in a XPS spectrum mean?

I was trying to figure out the different peaks in a XPS spectrum for Molybdenum, but I could not understand them. About XPS, I know that this technique is based on the binding energy of the electrons ...
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1answer
262 views

Explanation of the Selection rule in light of IR spectroscopy

I am in mathematics, but I am writing a paper on molecular vibrations (because you can use representation theory to handle this). I want to prove the selection-rule, but I also have to give a ...
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264 views

How much CO₂ should one expect in an IR spectrum?

I ran an IR spectrum ($\ce{KBr}$ pellet) and found a sharp absorbance at $2360 \text{cm}^{-1}$, which was unexpected. As far as I can tell, this indicates either a nitrile or $\ce{CO2}$. I know that ...
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What causes Copper Rose?

We made a solution of Tetrakis Copper(I) hexafluorophosphate and the usual color is yellowish. As it oxidizes to Cu(II), it should turn blue. However, our current mixture has an off color that is ...
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266 views

Can ammonia be detected by a 1D-1H-NOESY experiment?

I'm not detecting ammonia in my samples while using a NOESY pulse program for a 1H-NMR experiment. Is it possible for ammonia to be detected by a 1D-1H-NOESY experiment?
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1answer
66 views

Fourier transform for spectroscopy spectra?

I was thinking back to my chemistry major days and remembering the bunch of cool spectra we produced by various means (HNMR, IR, UV/Vis) and I remember all the cool 'self-interference' like couplets, ...
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49 views

Kinetic energy of electrons emitted in Photoelectron Spectroscopy

In multiple sources (example), I found the information that the kinetic energy $E_k$ measured using (Ultraviolet / X-ray) Photoelectron Spectroscopy is given by: $E_k = h\nu - B.E._F - \phi_{spec}$ ...
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150 views

IR Spectroscopy for Bonds in Sodium Triphosphate

I prepared a sodium triphosphate and wish to determine which bond corresponds to which vibration wave length on the spectroscopy graph. Is there some resource including any table for this or should I ...
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78 views

What is the 'ancestral term' in the LS coupling scheme?

On the physics.nist.gov site: http://physics.nist.gov/Pubs/AtSpec/node06.html The table titled "Atomic structural hierarchy in LS coupling and names for the groups of all transitions between ...
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153 views

Spectral analysis of periodic table of elements in time domain

I'm trying to get the spectral analysis data of the periodic table of elements in the time domain format or find a site that has the data in the time domain format. All the sites I know have the data ...
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1answer
577 views

What is the bandgap value of SiO2?

Using Diffuse Reflectance Spectroscopy, I have obtained the band gap for $\small\ce{SiO2}$ (purchased from a chemical retailer) in the range of 3.25 to 4.75 eV. I would like to know if the values ...
6
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1answer
455 views

Extracting elemental ratios from X-ray photoelectron spectroscopy (XPS)

Is it possible to extract information on elemental ratios from X-ray photoelectron spectroscopy (XPS)? For example, I am reading a paper and in it they say that the carbon to oxygen (C:O) ratios of ...
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1k views

Temperature dependence in absorption spectroscopy

What are some qualitative guidelines one should know regarding the temperature dependencies (of the gas and maybe the radiation, if that makes sense) for an absorption spectroscopy measurement? How ...
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227 views

When simulating spectral line broadening, which convolution is preferred?

Many computational chemistry packages permit the calculation of vibrational and electronic spectra. These spectra are obtained as a set of discrete eigenvalues however they are often convolved with ...