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. allure123

    Discovering Constant B in Rotational Spectroscopy of CO Molecule"

    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:
  2. R

    Fluorescence Spectroscopy and Stokes Shift

    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...
  3. B

    Why does spin-spin coupling cause splitting in NMR spectroscopy?

    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...
  4. G

    What Forces Cause Rotational Emissions?

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

    Laser Induced Breakdown Spectroscopy

    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...
  6. fricke

    Raman Spectroscopy: Why Peaks of Stokes Higher than Anti-Stokes?

    Why do peaks of Stokes higher than peaks of anti-Stokes in graph of absorbance unit against wave number?
  7. madhusoodan

    Why are core electrons removed from atoms on X-ray irradiation in XPS?

    [Mentor's note: Post moved to its own thread] Hi Please let me know why core electrons are removed from the atoms on x-ray irradiation in XPS, though it was easier to outer electrons?
  8. I

    Raman Spectroscopy Processing Software

    I am looking for a program that allows me to process my Raman data. What i want to do is to do integrations under certain intervalls, but also baseline corrections, noise reductions and so on. I have been coding a little bit on Matlab, but gave up once i realized I had no idea how to fix the...
  9. S

    Gamma-Ray Spectroscopy SCA vs. MCA

    A single-channel analyser (SCA) counts the number of voltage pulses whose height falls within an adjustable range. A multi-channel analyser (MCA) sorts the pulses according to height and counts the number in each spectral window to give a spectral energy distribution. Does this mean the...
  10. Y

    Study molecular conformation using optical spectroscopy?

    I want to study the molecular conformation of conjugated polyelectrolyte (CPE) using optical spectroscopy. Obviously a lot of people have used optical spectroscopy to study the structure of conjugated polymers, including this conjugated polyelectrolyte. However, they did in when the CPE is in...
  11. popopopd

    Spectroscopy hookes law, derivation?

    hi, i am a lillte confused why the equation for hookes law is 1/(2pi*c)*sqrt(k/m_reduced)? where does c come from? http://www.massey.ac.nz/~gjrowlan/intro/lecture5.pdf - slide 8. also, is there any particular reason why we use reduced mass?
  12. L

    UV-VIS Spectroscopy question

    Hello everyone, I'm quite new to lab work and I have the following question: I'm doing immobilisation on enzymes and I want to quantify how much enzymes is bound to my material after immobilization. I'm using UV-VIS for this. Before the experiment itself I want to a calibration with known...
  13. B

    VSCPT 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 which they can't absorb light. I have found same papers but they are too detailed for my...
  14. Jalo

    Spectroscopy - Forbidden transitions appearing in spectrum

    Homework Statement Why do supposedly forbidden transitions appear in experimental spectrums? Homework EquationsThe Attempt at a Solution I'm really puzzled as to why they appear. Can it be due to transitions on higher energy levels that happen to be equal to the forbidden ones?
  15. E

    How to know the shape of a specific location on Earth?

    How do you know the shape (land altitude, roughness, etc.) of a specific location on Earth through a satellite? For example, if a specific place is covered by clouds is there a way to know the shape of the ground at this specific point? I have read through the absorption spectra of the...
  16. T

    Infrared spectroscopy of water

    We all know that angular molecules have 3N-6 vibrational degrees of freedom. So, why lots of books show that water has more than 3 modes of vibration, like rocking, wagging and twisting? Another example is -CH2 group. You can see what I said here: http://chemistry.ncssm.edu/watervibCS.pdf...
  17. K

    Understanding Absorbance Values in UV Spectroscopy

    Hi guys, please can you kindly help me. I am getting an absorbance of over 6.0Abs for my experiment. However, when I am reading posts they mention that an absorbance above 1 is not reliable. Please can you explain so that I can understand. Thanks
  18. T

    Understanding Spectroscopic Term Symbols: Unraveling the Confusion

    Terrm symbols are really letting me confused. A spectroscopic term or term symbol is used to identify different arrangments of a given electronic configuration. For example, to carbon in ground state (1s² 2s² 2p²) there are a lot of different possible values for ml and ms, and term symbols can...
  19. B

    Infrared spectroscopy to find water absorption lines

    Hi I am currently trying to find the water absorption lines by using a Michelson interferometer, as a detector I am using an ocean spectrometer. The data obtained is thus the spectrum's "received" by the spectrometer. Am I right to assume that in order to find the absorption peak/peaks I should...
  20. B

    What gases can be absorbed between 800 and 1000nm wavelength?

    Hi I was wondering if anyone could tell me what gasses are absorbed between 800 and 1000nm wavelength and weather there is a book that lists all the gas wavelengths that can be absorbed in this region Thanks bertopolis
  21. B

    Gases I could expect to see using an IR receiver

    Hi I was wondering if someone could tell me what kind of gases I could expect to see using an IR receiver between the wavelengths of 110 and 330 nm. As well as this id love to know what kind of glass could be used in order to not interfere with the actual results. Thanks a million
  22. Domenico94

    Where Can I Find Detailed Information about Nuclear Magnetic Resonance Machines?

    Hi everyone. I'm just looking for an online description of the nuclear magnetic resonance machine, with explanations of all components, and their physical principles...anyone can help me? Giving me any link to a website talking about it? In addiction, could be this be a valid topic for a...
  23. chikou24i

    Exploring the Fundamentals of Instrumental Spectroscopy: A Guide for Scientists

    Hello ! what do you suggest as a good book for instrumental spectroscopy ?
  24. Dadface

    What is the positronium spectrum and why is it difficult to display?

    The energy levels of positronium in eV are given by: En = - 6.8/n2 From this the positronium spectrum must contain some frequencies smaller than those of gamma rays including some lines in the visible spectrum. My problem is that I have been trying to find photographs and other details of...
  25. S

    How to Calculate Excited Molecules in O2 Gas Using Spectroscopy | Mark's Guide

    Hi All, Lets say I know the absorption cross-section of a gaseous species e.g. O2. I have a pulsed laser of a certain energy and of pulse duration, which will hopefully guide me with the number of photons and I focus that laser beam into a stream of O2 gas. Can I calculate the percentage of...
  26. P

    Alpha Particle Spectroscopy - Is My Method Correct?

    Homework Statement Hey, first time poster here, I'm current writing up a lab report I just wanted to check my method is correct. I'm doing alpha particle spectroscopy using a cloud chamber setup. Most published reports seem to vary pressure (so the mass thickness varies). Our chamber let us...
  27. T

    2D Fourier Transform Infrared Spectroscopy

    I'm recently new to the field of 2D Fourier Transform Infrared Spectroscopy and am learning its applications. I would like to know its applications in biology. Specifically, is there anything in the 400 nm to 1000 nm range that is important in protein structure, protein dynamics or biology in...
  28. V

    Paschen notation in atomic spectroscopy

    I was trying to understand electronic excitation in Xenon. Most of the research journals are denoting different excitation levels in terms of Paschen notation, which i think, is generally used to represent excited states of inert gases. Can someone please explain how to use this paschen notation...
  29. S

    Optics: Design of Beamsplitter Ge on KBr substrate

    Hi there, I am making a beam splitter for an FTIR, but I do not know the anatomy of a beamsplitter of this type, does anybody have information on the design of these? I plan to order KBr crystal windows and apply the Ge coating myself using physical vapor deposition and assuring quality with a...
  30. K

    ESR Spectroscopy: Hydrogen vs. Deuterium G-factor

    Hi. I did an esr-experiment, analyzing hydrogen and deuterium. I am wondering: Why do the atoms not have the same g-factor?
  31. T

    Can Vibrational Spectroscopy Reveal Combinations of Normal Modes in Molecules?

    In vibrational spectroscopy we read peaks related to normal modes of a molecule. But I just can't understand: we can have a combination of those normal modes of vibration, right? So how can I read a spectrum of a molecule if this molecule can absorb a frenquency that might excite a combination...
  32. R

    What could be the compound in this spectra with peaks at 154 and 154+2?

    Hi guys As part of my degree I've got to analyses a set of spectras unknown compounds. I've managed to do them all so far, but seem to be struggling on this one particular set. Here's the spectra that I have to analyse: http://imgur.com/a/oVNYe So far I think it might be an ester with a Alkyl...
  33. B

    Accurately and Quickly Interpreting NMR/IR Spectra

    In examining the IR spectrum, I noted that there were peaks for CH2-x where x is bromine, methylene (2 peaks) and a peak corresponding to a methyl group; I concluded that I've synthesized n-bromobutane. Is the method I used to interpret my spectra sound? *CDCl3 was the IR solvent In addition...
  34. C

    Solid state ultrafast spectroscopy - a good research direction?

    I am interested in ultrafast optical spectroscopy of solid state materials. The unique measurements and especially the process of developing new measurement tools for the optical measurement of quantities that are hard to measure in other ways, and the learning of transferrable skills, make this...
  35. R

    Difference between X-ray Diffraction techniques and Raman spectroscopy

    Hi everyone, I'm little bit confuse about non destructive techniques such as XRD (X-ray Diffraction) and Raman spectroscopy, I know that both techniques can determine the crystal structure of the certain materials, and also, I know that XRD is working with the principle of emission of x-ray...
  36. R

    The difference between Auger Electron Spectroscopy and XPS.

    How can we distinguish between Auger and core-level loss peaks (such as in XPS) in the secondary electron spectrum?
  37. P

    Spectroscopy technique for detecting water saturation front in polymer

    Hello all, I am a grad student in materials science. As part of a research project, I need to measure/detect the velocity of a water saturation front moving through polymers (a few materials, most fluoro/perfluoropolymers). The ultimate goal of the project is to determine the permeability of...
  38. Q

    Pump probe spectroscopy as linear process away from equilibrium

    Greetings everyone, I have recently been trying to generate some theoretical pump probe spectroscopy data. The typical way to do this is via third order time dependent perturbation theory and applying phase matching approximations / Rotating wave approx etc etc. There is however, no...
  39. Einj

    XYZ spectroscopy and the existence of possible 4-quark states

    Hi everyone, I've been studying the so-called XYZ spectroscopy and the existence of possible 4-quark states. The LHCb collaboration recently confirmed the existence of a particle called Z(4430)^-. This particle is the unambiguous evidence for the existence of 4-quark states. From what I...
  40. H

    Why Can't Bainbridge Mass Spectrometers Use Multiple Detectors Simultaneously?

    Why is it not possible to use multiple detectors in a Bainbridge Mass spectrometer,so that we can record the intensity of each ionic species at the same time? I got this question because whenever i read about Time of flight mass spectrometer,i find that one of its advantages is listed as the...
  41. B

    Spectroscopy: clarification about doppler shift

    I've just begun to study spectroscopy, and I need a clarification about the Doppler Effect. Consider a cell containing Rubidium and enlight it with a laser. Connect the system with an oscilloscope and give a triangular wave as input (so you can know when the Rubidium is resonant). This is the...
  42. T

    Gamma spectroscopy- Fine Gain Coarse Gain factors

    I'm currently doing a spectroscopy lab where you use a scintillator and Cs-137 to obtain a Cs-137 spectrum. I calibrated this spectrum using the known gamma energy for Cs-137 at 662 Kev at the photo peak. I am now trying to use this calibration for a Co-60 spectrum. The problem is that when I...
  43. K

    How were atomic masses determined before mass spectroscopy existed?

    I remember a professor mentioning something about how scientists did this when we were discussing the history of the periodic table (they originally ordered it by atomic mass). I can't seem to find an answer online without digging through a lot of stuff...there was one article on this topic...
  44. K

    Maximizing Vibrational State in Raman Spectroscopy: Techniques and Pricing

    I have read about it, and interested. Here's some questions not obvious in the references I read. For the strokes where the laser final result is higher than the ground state or more accurately described by Wikipedia "If the final vibrational state of the molecule is more energetic than the...
  45. C

    What is Channel Number? (In gamma spectroscopy)

    Really quick question. In a graph like this: http://en.wikipedia.org/wiki/File:Cs137_Spectrum.PNG Source What does the Channel Number represent? Also, just to make sure, am I right in saying the count rate is \frac{\delta m}{\delta t} ? where m is the cumulative number of scintillations and...
  46. A

    Rotational Spectroscopy Question

    Which of the following molecules can be studied by purely rotational spectroscopy? a) NH3 b) N2 c) CH4 d) SF6 e) CS f) CS2 The attempt at a solution[/b] To my understanding, using only rotational spectroscopy could be used to study b) N2 and e) CS but I am not sure about my answer...
  47. Borek

    Mass spectroscopy and electromagnetic radiation

    Bear with me, I am a chemist :shy: As far as I understand, every accelerating charge emits electromagnetic radiation. In mass spectroscopy charged molecules/parts of molecules move in the magnetic field which bends their trajectories using Lorentz force. That means they are accelerated...
  48. E

    Using CCD acquire spectroscopy

    The question could be stupid,but It really confused me. when we capture spectroscopy using reflected grating and CCD, Does the diffracted light must be focused on the plane of CCD (using a plane grating),or it must be collimated to arrive the CCD.
  49. V

    Something weird with my Kurie-Plot (Beta Spectroscopy)

    So I'm doing a Beta Spectroscopy of Sodium and apart from the Energy Spectrum, I'm intending to use the Kurie Plot to incorporate the Coulomb Correction Factor F(Z,p). But when I try plotting the data, my K(Z,p) has an incredibly huge number, on the order of 1020 and the linear graph looks...
  50. A

    Gamma spectroscopy regarding Cs-137

    Hi, I was doing a measurement on a Cs-137 source, strong enough so that my detector registers a sum peak. I can't get my head around A, the peak at ~80 keV.. I get B (backscatter peak), C(compton edge) and D total abs.peak. I tried with a weaker Cs-137 and I saw the 35keV (Ba) but no...
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