What is Spectroscopy: Definition and 332 Discussions

Spectroscopy is the study of the interaction between matter and electromagnetic radiation as a function of the wavelength or frequency of the radiation. In simpler terms, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum; indeed, historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Matter waves and acoustic waves can also be considered forms of radiative energy, and recently gravitational waves have been associated with a spectral signature in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO).
Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of physics, chemistry, and astronomy, allowing the composition, physical structure and electronic structure of matter to be investigated at the atomic, molecular and macro scale, and over astronomical distances. Important applications arise from biomedical spectroscopy in the areas of tissue analysis and medical imaging.

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  1. C

    Exploring the Absolute HOMO: Spectroscopy & Beyond

    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...
  2. T

    Fourier-transform Infrared Spectroscopy Thin Film Thickness

    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...
  3. F

    I Angular dependance of NEXAFS spectroscopy - derivation

    Hi all, this is my first time posting so I hope it's in the right place, if not I apologise. I'm trying to understand the angular dependence in NEXAFS spectroscopy for linearly polarised light. So from what I understand, the quantum mechanical description of the excitation process for a single...
  4. C

    Interference of light, emission spectroscopy prac. report

    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...
  5. A

    Understanding Infrared Spectroscopy: Analysis of a Recorded Spectrum

    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
  6. R

    IR spectra (in thermal scope vs IR spectroscopy)

    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...
  7. Arup Biswas

    Books for Solid State physics and spectroscopy?

    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 !
  8. R

    I What Causes Huge Raman Shifts in Water?

    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...
  9. R

    A Give some ideas on project about spectroscopy

    I m studying in m.sc. physics in final year. Give some ideas about spectroscopy project.give some suggestions and topics.
  10. Eureka99

    Electronic transition in organic compounds

    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...
  11. S

    I Alpha Spectroscopy: Why does Peak Resolution Change?

    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...
  12. emma

    How should I calculate conductivity

    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)?
  13. _maxim_

    A Best coil design for homogeneus NMR RF pulse on liquid discs

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  14. J

    I Interpreting Copper & Argon Emission Spectral Lines with Plasma Spectroscopy

    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...
  15. J

    I How can I identify the appropriate spectral line for Doppler calculation?

    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...
  16. Guilherme Franco

    I Where to find in-depth info about each star's composition?

    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...
  17. M

    Physics New to Spectroscopy? Let's Connect and Exchange Ideas!

    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...
  18. N

    Difference between absorption spectroscopy and extinction

    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
  19. P

    A Detection limits for Raman spectroscopy

    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...
  20. Mzzed

    I Instrument Line Function of a Spectrometer

    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...
  21. J

    I Nitrogen-Vacancy centres in Diamond for NMR spectroscopy

    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...
  22. M

    I Spectroscopy of Rb - crossover peaks more intense?

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  23. JeremyC

    IR and Raman spectroscopy question

    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...
  24. H

    B Spectroscopy before tunable lasers?

    how was it done?
  25. KarolinaPL

    NMR spectroscopy, ligand's influence

    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...
  26. senobim

    Relate wavelength and energy scale

    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...
  27. senobim

    Laser Spectroscopy: Calculating Transmitted Intensity

    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...
  28. A

    I Does ARPES Only Show Fermi Surface of a Structure?

    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...
  29. mfb

    I First atmospheric spectroscopy of Earth-sized exoplanets

    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...
  30. Srv44

    Dye doped spectroscopy interpretation

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  31. A

    I (old?) spectroscopy analysis notation

    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...
  32. Dade Murphy

    Gamma spectroscopy over time?

    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...
  33. LanaK

    UV-Vis spectroscopy: non-bonding electrons and chromophores

    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...
  34. Y

    A Raman Spectroscopy vs. Inelastic Electron Tunneling

    I am a first year graduate student in physics and am becoming familiarized with Raman spectroscopy to study structure of materials based off of their vibrational states. In some personal study outside of this, I came across the idea of inelastic electron tunneling spectroscopy (IETS) and was...
  35. Matthew Adams

    I Emission spectroscopy of an acetylene flame

    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...
  36. I

    I Transient Absorbtion Spectroscopy

    Hello there! The picture attached in file shows typical spectrum of transient absorption spectroscopy. Is it possible to have the same components in quantum dots?
  37. I

    A Exploring PP Spectroscopy to Study Nanocrystals

    Hi there, My question is regarded to PP spectroscopy, I studied this method, expertimental set-up, transient absorption, and it is quite familiar to me. But nowhere I can't find any material that shows how this method can be used to study Nanocrystals, and that is what I am seeking for now...
  38. Developer_CM

    Gamma Ray Spectroscopy - 97 keV Peak for U238 Metal

    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...
  39. davgonz90

    Why do deshielded protons require more energy in NMR spectroscopy?

    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.
  40. O

    Analysis of Atomic Absorption Spectroscopy results

    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...
  41. I

    I Pump Probe Spectroscopy: Introduction to a Powerful Technique

    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 ;)
  42. J

    I Localized and delocalized states, meaning? in Organics

    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...
  43. Jalo

    I Photoluminescence Excitation (PLE) vs PL spectroscopy

    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...
  44. D

    A About X-ray Photoelectron Spectroscopy

    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...
  45. F

    Laser Spectroscopy: Exploring the Depths of Molecules and Surfaces

    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...
  46. S

    Analysis of Urine with Spectroscopy: Urea & Creatinine

    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...
  47. D

    Rutherford Backscattering Spectroscopy, Counting Statistics

    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...
  48. W

    Naphthalene impurities spectroscopy

    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...
  49. B

    MR spectroscopy J-coupling phase

    My lecturer said the following: (see uploaded image) However the two statements are not the same, which is correct? thanks
  50. T

    Spectroscopy and the doppler effect

    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...
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