Spectroscopy Definition and 305 Threads

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

[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?

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...

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?

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...

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?

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...

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...

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

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...

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...

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

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

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...

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

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...

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...

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...

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...

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...

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...

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

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...

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...

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...

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...

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...

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

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...

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...

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...

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...

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...

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...

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...

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...

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...

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.

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...

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...

Am currently doing an undergraduate project work on 'estimation of radiological risk pose by U-238, th-232 and K-40 in rock samples' . The instrument I'll use are NaI(TI) crystal for scintilation were the gamma rays from the source(my rock samples) interact with the crystal through photoelectric...

What are the axes(horizontal & vertical axes) in a Raman spectrum?

Dear all, I learn that photoelectron spectroscopy can measure the work function of solid semiconductors. However, some research papers reported it measured the ionization potential of solid semiconductor nanoparticle films. As we know there's obvious difference between the work function and...

Has anyone read or seen any articles that might highlight the techniques of Stimulated Raman Scattering Spectroscopy? Or just any knowledge on the process they would be able to share? I am having a tough time getting a hold on the process and if anyone has any useful information or articles that...

Hi! In my lab class, we are using a photomultiplier to examine gamma ray emission lines and determine absorption coefficients of different radioactive materials. Homework Statement As we test for absorption (by layering on metals, incrementally increasing the thickness), we consider spectral...

Homework Statement For our lab, we looked through the spectrometer to find the spectral values for Helium, which after being plugged into an excel spreadsheet, yielded an equation which I could use to find the wavelengths for Hydrogen. We were told to solve for R, which I did. However, at the...

When we want to view the spectrum of light emitted by a certain gas (via spectroscopy) how much voltage do those gas discharge tubes end up having? I know they are very high voltage, but how high exactly? Now if I were to look at an incandescent light bulb through a spectroscope, I would see...

Hi I'm a first year undergrad student studying Electronics. I am really interested in creating a working Laser Induced Breakdown Spectroscopy(LIBS) setup in my summer break which is June and July. I'm reading about it these days, although still scratching the surface. I'm confused whether I'll...

Homework Statement The bond length of CO is 1.128 Å. At what wavenumbers do the first three rotational transitions appear Homework Equations μ= (m1m2/m1+m2) I = μr0^2 B= h/(8∏^2)IbC ΔE = 2B (J+1) The Attempt at a Solution For the first equation I got (12 x 16) / 28 =...

I have read from time to time (e.g. Lakowicz) that the fluorescence spectrum of a substance is not generally influenced by the wavelength excitation source. On the other had there is a correlation as exemplified in excitation-emission matrix spectra for example. The obvious case is for...