Spectroscopy Definition and 305 Threads

When you are setting up a spectral acquisition with a raman microscope, what does the exposure time mean? I would expect this to mean the amount of time the sample is exposed to the laser, but it doesn't seem like that can be true if it takes around 20 minutes to acquire the spectrum with a 2...

Hello, I've taken a spectrum of a U238 sample, and I keep getting this hill of low energy values. Any ideas as to what could be causing them? Sorry about the weird screenshot; it's the only one I had and my friend couldn't see the dots, so i had to go over them in paint.

So, this has been bugging me for years (seriously). So my spectroscopy course says the following: 1) In an atom, for a closed subshell, for each electron possesing an m_l quantum number there is another electron possesing -m_l, which means that the sum M_L = \sum {m_l} = 0. I have no problem...

What is a difference between NAI and Germanium detector in terms of accuracy?

Can one monitor dynamics of a specific protein domain (helix, strand etc) by Raman Sp? If one labels a specific residue with an isotope, like in NMR, can one use that to monitor the dynamics of the region that encompasses this residue?

Why do we get line spectra from absorption/emission of atoms, but band spectra from absorption/emission of molecules? As I understand the Heisenberg Uncertainty Principle mathematically, some operators do not commute and as such, the order of measurements determines the results. In regard...

When a molecule, let's say butane is placed in an external magnetic field and its hydrogens align parallel or antiparallel to the direction of the magnetic field, do 50% of the H atoms align parallel to the B field and the other 50% align antiparallel or what? If so, when they radio waves are...

hi, i went through some textbooks about photoelectron spectroscopy and was looking for information on how it is used to determine the structure of a surface. but they mostly focus on how it can be used to identify the identity of the sample and some of the terms in the books were too...

Please can anyone suggest a good book on raman spectroscopy. cheers.

Hi, For someone my question could be very simple but I couldn't find a well explain paper that explain this to me. In a Raman spectrometer the stokes and anti-stokes wavelength will always be grater than the laser wavelength used?. I have this confusion because I saw that Raman...

Say I want to monitor the interface of an electrochemical cell via IR spectroscopy. If H2 gas is generated, there must be a characteristic IR signature to this event. How can I figure out what this is? Are there calculations for this? I'm sure this is in the literature somewhere, but I...

Hi Why does a bond stretch or vibration have to cause a change in dipole moment to be IR active? Presumably all vibrational modes depend on energy aborption to occur whether they cause a change in dipole or not. I'm presuming that only those vibrational modes that cause a dipole change are...

I'm looking for the more precise value for the 2S-2P lamb shift transition frequency. I found the value 1 057 844.0(2.4) kHz in the National Institute of Standards and Technology website: http://physics.nist.gov/PhysRefData/HDEL/transfreq.html. Can someone tell me if there is a better value...

Hi Are there any protons that do not show up on proton NMR as I am analysing an NMR spec (of a known molecule but I don't know what it is!) and I can't get my integration to equal the number of Hs in the empirical formula of the molecule Many thahks

Hi In UV spectrscopy, is the definition of absorbance (A = ecl) derived from the definition of transmission (T = It/Io) where It is the transmitted light and Io is the incident light, or is the definition of transmission defined from absorbance. Also A = -log(T) and T = 10^-A = 10-ecl...

Hi What units does incident light have in UV spec? Is it joules? Transmission is defined as transmitted light / incident light so any units of light simply cancel out to give a unitless number. I presume the original units were joules as light is EMR? Perhaps its more complicated than that...

Hi I'm a little bit confused about infrared spectroscopy. My basic understanding (which was obviously wrong) was that molecules absorbed EMR in the infrared region and that this caused vibrations in the molecule. Some vibrations/stretching cause a change in charge distribution and for reasons...

my question is why oxygen lines does not appear in metal oxides spectrum taken at 532nm wavelength of Nd:YAG laser at atmospheric pressure. and what is the criteria for selecting emission lines for analysis?

Why are sp2 carbons more downfield than sp3 carbons? Is it because the bond length of sp2 carbons is shorter (electrons are more localized-thus more shielded)?

Homework Statement Two first-order spectrum lines are measured by a 9650line/cm spectroscope at angles, on each side of the center, of +26*38', +41*02' and -26*18', -40*27'. Calculate the wavelengths based on these data.Homework Equations \lambda= (d/m)sin(\theta) The Attempt at a Solution i...

Can anyone help me find this book: Plasma Spectroscopy, Author: (H.Griem) It is the most famous book and it is the very basic level of plasma spectroscopy, if you find it that will be great for everyone in this field. thank you

What are some simple graphs that can be created (in Matlab) relating to Raman Spectroscopy or just basic equations that can somehow be related to it? So far all I've done is graph E=E_0 cos (wt + 1/2 αt^2). And any suggestions of things I should read up on about the topic and understand...

Hello Group! I'm working on analyzing Raman spectra of proteins. I'm particularly interested in learning more about the signal processing of the amide I band. If anyone has any experience with Peakfit program or Origin, Savitsky-Golay smoothing, or amide I deconvolution for secondary...

i have a mossbauer data for a ferrite sample in terms of channel vs counts, i need to convert it into velocity vs counts. i don't have any software, i tried to download the demo versions of MOSSWIN and IGOR PRO but i am unable to know how to convert them. Please guide me for the conversion.

What's the difference when I observe the emission lines of say, Hydrogen or Neon, on two diffraction gratings having different line spacings? Will there be colors that will only be observed in one and not the other? Thank you!

Hello, Gentlemen! Is there anybody who has ever published in the "Internet Journal of Vibrational Spectroscopy"? I had a couple of article published there (in the years 1999 and 2000), and everithing with the site of the Journal www.ijvs.com was correct until approx. one week ago...

Hi all, Got a bit of a problem with a lab experiment at uni (I'm not sure if this is the right place to post this, mods feel free to move it if necessary!) Anyway: We're trying to get a plot of efficiency against energy for a planar germanium detector. We've got spectra for different...

How can astronomers use earth-based spectroscopy to determine the chemical composition of nebulae, stars, planets etc. when the light has to pass through the Earth's atmosphere before it's detected? Does the chemical composition of the Earth's atmosphere pose a problem?

Homework Statement if light incident on a grating makes an angle phi with the normal of the grating, show that the equation m(lambda)=d(sin(theta)) becomes m(lambda)=d[sin(theta-phi)+sin(phi)] Homework Equations m(lambda)=d(sin(theta)) d=spacing of slits, theta=angle displaced from...

From uncertainty relationship ∆E τ ~ hbar, what is the lifetime for a state that gives rise to a line of width 0.1 cm^-1? what about for 100 MHz? How do you get the energy term? I'm really not sure how to do this, would appreciate some insight, thnx.

Hello I am looking for a few textbooks to digest, I am learning the fundamentals of spectroscopy, in particular absorption spectroscopy of gases. Are there any great textbooks out there on these subjects? I feel I need a more solid grounding. Any undergrad would be welcome, as would any...

Hey everyone, Over the past few days I have been having trouble with finding research for my optics project. The topic I chose was supposed to be the physics behind how astronomer's and astrophysics measure the Spectrum of the Sun ans specifically the mathematics/physics behind the...

Hello, I am having a little trouble getting to the fundamentals of FM (laser) spectroscopy. As I understand from some research, the frequency of the incident beam is varied with a second frequency much larger than the first: Bjorklund 1980: "The key concept is that the modulator is driven at...

All of my questions that follow revolve around the question of atomic geometry/structure as it relates to quantum mechanics. On every high resolution (1 angstrom, and a few less than 1 angstrom) TEM image I have seen, atoms appear as spheres. I then found a website that claims it has visualized...

Hi, I have measured some spectrums from various gamma sources and I was wondering what kind of fitting I should do to determine the Compton edge. I have access to Logger Pro, Excel, and mathematica. I have fit the photopeak with a Gaussian so I know the uncertainty in the Compton edge, I...

Quoting from wikipedia I understand what symmetrical and antisymmetrical stretching come from and the number of vibrational mode(s) can be predicted basing on the concept of degree of freedom. However, for scissoring, rocking, wagging and twisting, are they considered as bending...

Hello, i ve got some questions on spectroscopy. surface states and quantum well states have free-electron like dispersions, they a more or less free states, so E ≈ k*k. d-electrons have flat dispersions, they are bound. My Question is: why have bound states flat dispersions? does this have...

I am taking my second semester of organic this summer. We are working on IR Spectroscopy and mass spectrometry in class. Is there anywhere that anyone knows about that may put it all together? Or can anyone maybe give me some tips on how to remember all of the main functional groups? I am...

i need help in determining thickness of thin film created by pouring volatime solvent with solute using HATR technique also would like to know how experimental design can be set with HATR technique quantification purpose.

hi i m studing AAS(atomic absorption specvtroscopy) technique.using beer"s law i plot a graph bw absorbance and concentration.then how can i make the quantitative analysis of my sample?

Hey guys, There is something I have known and applied for a long time, that the greater the length of an interferogram the greater the resolution of the resulting frequency-domain spectrum. But I've never fully understood why, I've always waved it off as something to do with the uncertainty...

Apologies for making a long posts, I just wanted to lay down the basic idea of what I'm doing at the beginning. I'm working on a home-made Michaelson type Interferometer. I'm trying to make few changes, mainly modulation of the black-body type radiation (Globar). Instead of amplitude...

I did a bit of x-ray spectroscopy in labs studying Fluorescence of some different elements. I was just wondering whether or not flourescence occurs in all elements? I'm sure I've read people talking about 'flourescecnt materials' or something like that. I can't think of any reason why it...

I'm a freshman physics major and I'm doing summer research on Raman Spectroscopy. I've read up on it a bit but I was wondering if there are any resources that would help me better understand or at least get a general idea of what this is.

In rotational (microwave) spectroscopy, the Kth energy level is BK(K + 1), B = constant. It turns out the each Kth level is (2K + 1) degenerate. Now, as the energy level increases, does this mean that a single molecule will be in all these states at once, or in one of them? Or does it...

Homework Statement I have attached the IR and NMR spectrum from lab. I have determined that there was a nitrogen present in the compound. There was no sulfur or halogens. The molecular weight was 138. The compound was solid and yellow color. It had a melting point between 124 and 134 C...

I wonder if anyone have an idea about the software (CASA) used for the treatement of data dounded by XPS analysis. If yes, I am in need to know how to remove the satellite peaks that may show in a spectrum. thanks

Hi, Does anyone know any good Linux/Unix software for analysing optical emission spectra? I've been searching the net, but I can't find any. The software I'm currently using is old, only for MS Windows, very expensive, and pretty much useless. So any suggestions would be much appreciated...

hi friends, I'm going to simulate the spectrum of a specific ion, with constant situation (like: density, temperature and etc). but I don't know what should I do first! thanks for your help :frown:

I've got the spectra for C5H8O2 (the spectral database confirms that it's ethyl acrylate) and treatment with hot aq. HCL causes the signals in the 1N NMR spectrum at d 1.3 and 4.2 to disappear. Does anyone know why this happens? Thanks!