Spectroscopy Definition and 305 Threads

What exactly is the absolute highest occupied molecular orbital? I think, as the name suggests, it's the absolute highest occupied molecular orbital in a molecule. Could it be determined using spectroscopy? Maybe, depending on the type. You could use UV-Vis if the energy gap between the HOMO...

I had an experiment involving FTIR (incoherent light source) to measure the thickness of plastic film through making use of interference fringes. I don't understand how the interference fringes can occur over a frequency range (in term of wave number ν for FTIR) and also how it can occur at the...

Ok, so I've got a practical report due tomorrow and I just wanted to clarify a few things. A bit of background knowledge first. The practical involved taking angular measurements for the emission lines of the Mercury spectrum using the apparatus, a spectrometer and a Mercury spectral tube...

I do attach a plot (pdf and Matlab) of a recorded spectrum where I do not manage to find the gas specie overlapping CO2 Could you help me? Best Alain

In thermal imager vs IR spectroscopy, they both look at the IR radiation of an object. What is the difference between the two.. I know IR spectroscopy look at the dipole moments of molecules. But in thermal imager.. do they also image the dipole moments of molecules? Also why you see images in...

Actually those to subjects are in our syllabus now! Please suggest me some books which will be easy to understand and somewhere maintain my academic syllabus too !

Hi, The following is the typical raman spectra of water. In their normal form, water molecules maintain a simple configuration: an oxygen atom is in the center and two hydrogen atoms are on the two sides symmetrically. Under ambient conditions, water molecules within liquid water give rise to...

I m studying in m.sc. physics in final year. Give some ideas about spectroscopy project.give some suggestions and topics.

Hello everybody :) I have a problem understanding the different types of pi -> pi * transition of organic compounds. I can't understand what's the difference between K-band, B- band, and E-bands, and I cannot find any explanation on the internet. Also I don't understand why benzene has two E...

I'm trying to understand why peak resolution changed in my alpha spectroscopy experiment. I've increased the distance between a Am-241 source and a silicon surface barrier (semiconductor) detector and taken spectra along the way, recording information about peak height and FWHM. As the...

Hello, I would like to ask if I have this data from impedance spectroscopy: frequency, Z(im), Z(Real), how should I calculate conductivity ? Should I use R(im) or R(re)?

Hi there, we have a NMR spectrometer equipped with a standard bore 54mm cryomagnet working at 14.1 T (600 MHz Larmor Frequency) produced by Oxford. I would implement a special probe capable of generating a RF pulse and reading a NMR answer from a sample that is not standard for such...

Hi, I recently started working on MPD Thrusters. During a recent experiment, spectral images (uncalibrated) were obtained. The thruster is made of copper and the propellant is argon. These two elements will be the source of emission spectral lines. I need help to interpret them. I have...

Hi, I was looking into Doppler shift calculations, and I came across this blog post. It gives a very simple and straight forward account of calculating the velocity of a star. Following is the summary the blog post: Spectrum of Alpha Centauri (A. Cen.) is obtained through Lhires III...

Hello. I couldn't sum my entire question in the title, so here it goes: I have a friend that needs information about the content of Iodine and Molybdenum in stars (from as much stars as he can). There are references to the content of many stars in books and papers, but most of them don't give...

hi friends, I am new to this forum and to this domain as well,i am basically a networking/IT guy, i am looking to do some project which is involving spectroscopy to find chemical composition in different elements. As i am new to this domain,i don't know how i can find a friend/guide probably...

Hello everyone I want to know what is the difference between Absorption and Extinction spectra. and in term of experiment how can get extinction spectrum. Thank you

This may be a completely terrible question, but does someone have an idea on the detection capabilities for raman spectroscopy of a bulk sample like human tissue (hair, blood, skin, anything)? I thought it might be fun to see if it were possible to use raman to identify exposures to chemicals...

I realize that in a spectrometer the spectral line being viewed will be the result of the actual spectral line plus an instrument line function as well (as seen in the linked image). What I don't understand is how this is produced? Someone tried explaining this to me once before but their...

Hello, I have been looking into NV in diamond and how it can be used for nanoscale magnetometry, and was wondering if anyone could help explain how it works or link to a paper that does. Is it just a spin 1 state (splits to 3 levels) that undergoes NMR or is there something else happening? I'm...

Hi, I am currently looking into the atomic spectroscopy of Rb using saturated absorption spectroscopy. So far I can observe the crossover peaks with hyperfine splitting. I am aware of why crossover peaks occur however do not understand why these transitions are so much more intense than the...

Homework Statement Sulfur hexafluoride is a centrosymmetric molecule with four infrared inactive vibrational modes: 346 cm-1 , 524 cm-1 , 643 cm-1 and 775 cm-1 The Raman spectrum of a liquid sample of SF6 (held at elevated pressures) was measured with a laser that has a centre frequency of...

how was it done?

Hi, i have been wondering about the influence of the ligands on metal NMR shifts, for complexes with metal like Pd, the ligands are 2 amine ligands, and they have also two chlorides in structure, cis or trans geometry. In DMF, when comparing the difference between the chemical shifts of the...

Homework Statement Light intensity is measured by monochromator and is given by I(\lambda ) = I_{0}\lambda ^{3} How to change it to the energy scale I(h\nu ) = ? Homework Equations Photons energy E = h\nu, E =\frac{hc}{\lambda } The Attempt at a Solution It's kind of strange to relate...

Homework Statement Unpolarized light of intensity I0 is transmitted through a dichroic polarizer with thickness 1mm. Calculate the transmitted intensity when the absorption coefficients for the two polarizations are α|| = 100cm −1 and α ⊥ = 5cm −1 Homework Equations Is it possible to say what...

I am reading about angle-resovled-photoemission-spectroscopy (ARPES). It seems that it is a technique that gives the energy dispersion as a function of the momentum k. However in all talks about it, it seems to be a technique that gives us the fermi surface of the given structure. I don't...

The Hubble telescope lead to the first spectroscopy of the atmospheres of two Earth-sized exoplanets, TRAPPIST-1b and TRAPPIST-1c. A large hydrogen/helium atmosphere could be ruled out - not that surprising, but still nice to have this confirmed. The main star, TRAPPIST-1, is just 40 light...

Hello all, I am working on a dye doping project and got a photospectrometry result as show in a picture for my thin film. Can anyone please help me interpret the physical meaning of the graph below? Thanks!

Hello, I've been studying spectroscopy in organic molecule and I came across an old data from 1934. 280(5b)(k,i±e), 297(1vd)(e), 354(1vd)(k,e), 378(1vd)(k,e), 398(Ovd) (e), 426(1vd)(k,e), 766(Ovd) (k,e), 807 (Od) (k,e), 817 (lb) (k,e), 842(1vd)(k,e), 862(2)(k,e), 878(3)(k,e), This is a piece...

Hello! These might be silly questions to the experienced, but this will be my first time trying gamma spectroscopy, so I'm a newbie. Firstly, I'm wondering if there's some software that will record changes in the spectrum over time? I know some people have been doing audio recording, but it...

Hello everyone, I'm just learning about UV-Vis spectroscopy, I have some questions and I would be really thankful for help. It's stated that apsorption happens when electrons go from ground to excited state. And that transition to excited state is easier for non-bonding electrons which I...

Hey there folks! This is my first post so please be gentle... ;-) One of my students has been studying the emission spectrum of an acetylene flame. A gas mixture from both an acetylene cannister & an oxygen canister is fed out to a nozzle, a flame is ignited and we study the emission...

I recently acquired a 39 gram sample of U-238 metal. I ran a gamma spectrum on the sample and found a major peak around 97 keV. I couldn't find any documents that mentioned this peak for U-238, but it is very prominent. I ran a gamma ray spectrum on a 5 gram Uranium Oxide sample and it also...

As you move to the left in the NMR spectrum, the protons become more deshielded. So why is it that they require MORE energy to change their spin? If they don't require more energy, then why is the left side labeled as high frequency? Thanks.

Homework Statement Hello, This week I ran an AA Spectroscopy experiment in my university, in which we had to analyze the percentage of Copper in a metal coin, and the containment of Iron in morning cereal. We used 2 standard solutions of 1 and 10 ppm (containing both Copper and Iron), and...

Hello there ! I am looking for a brief description of a pump probe technique. I am rather new to this subject, so I am interesting in such a good introductory articles or books. Your own explanations are always welcome ;)

Looking (if possible for some of you) a concise but non mathematical explanation of the terms localization and delocalization? This questions is related to Quantum Molecular Physics. When reading a paper of Spectroscopy and allowed transitions, I encounter the following phrase " [Intersystem...

I'm not sure I understand what information we can get from Photoluminescence Excitation (PLE) that we don't get from regular PL. Let's imagine we have a sample with emissions between 700nm and 850nm. If I'm not mistaken in a typical PL experiment you'd just use a laser source with a wavelength...

Hello, I am trying to create peak models for some XPS spectra. I have a decent intuition of the chemistry of the samples, and I obtain really good residual standard deviation values for the modeled data; however, some of the FWHM of the modeled oxidized species (C and P) on the narrow scans are...

So I came across this article while looking for laser spectroscopy. From what I see most of the laser spectroscopy requires the laser to beam directly at the ample to retrieve a spectral image about the sample. I want to know if it is possible to reverse the spectral image back into a 3D image...

I'm an electrical engineer, and right now i am working with a system that is supposed to detect the amount of different substances in urine. Including glucose, urea, creatinine, ketons, proteins, leukocytes, nitrite, urobilinogen, hemoglobin and bilirubin. The way we want do detect the...

Homework Statement I am given a numerical example (to be solved with pen, paper and calculator only) of an RBS spectrum of a AuAgCu-alloy on a glass-substrate. The question is "Can you get the composition? How accurate is the result?Homework Equations All the Rutherford Backscattering...

Dear all, I was doing cleaning of naphthalene through zone refinement. After it is finished impurities from the naphthalene concentrate completely in one place of the ampule (lower part). I was interested to see which type of impurities are collected and did a spectroscopy measurement. Couple...

So the prof shows us how to tell if an object is red shifted, by comparing two spectra (i assume of the same object). The emission lines had similar gaps but were shifted right, therefore moving away from us. How can you obtain two different spectra of the same object if it's constantly moving...

So I am given a rotational microwave spectrum of a molecule (CO specifically) and I have to find the constant B if it's not elastic , the constants B and Dj if it is elastic. Anyone know how to do that? :frown:

This is a question on fluorescence spectroscopy so physics/chemistry. What causes a large Stokes shift in the spectra? I know what causes the shift in wavelength, i.e., a relaxation of vibrational states before de-excitation to the ground state, but what actually causes a (very) large Stokes...

Hi. I was wondering if you could please help me understand something about NMR spectroscopy (MRS). I know that the chemical shift (Hz) of a particular chemical will vary with B0. As I understand (although this may be wrong) ppm is frequency independent so the peaks should always be in the same...

I was curious about what forces can be applied to a molecule to cause a rotational emission.

Hi, I'm trying to use LIBS technique to figure out elemental analysis of human nails. But every time i run the experiment, i get the emission line of metal instead. The sample holder is indeed made up of metal. What should I do to overcome this problem? Since i have small size sample, I'm...