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Raman Spectroscopy graph question

  1. Apr 27, 2010 #1
    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? I've never taken a QM course but I have to learn some of this stuff and I'm not sure whee to start.
     
  2. jcsd
  3. May 4, 2010 #2
    i've also want to see how is the output of raman looks like and still searching for the right equation, may i know, how is the graph looks like after you have done tha equation by matlab..maybe you can show me sometimes..TQ
     
  4. May 5, 2010 #3
    Visible Raman

    HAi...i'm new here and really need help regarding to my topic.
    1. Actually i've just going to futher my study and trying to focus on Raman spectroscopy instrumentation. I've seen lots of instrument prepared using laser as their sources, but instead of high cost, and difficult in calibration, laser also is temperature effected. Is it possible to used Light emmiting diode (LED) ? and try to used PMT as a detector coz i've just want to detect from skin which at the visible wavelength (300-500nm).
    2.I've seen many types of raman such as SERS, SERRS, Hyper Raman, Stimulate raman and many others...what type of raman that suitable with my project coz i'm doing detection on the skin which depth in range of 300-500nm.
    3. In what area should i focus coz i've read some paper and really got confused on that topic..any problem during set=up the instrument? really really hope to help me..plssssss. TQ
     
  5. May 11, 2010 #4
    Re: Visible Raman

    i've been waiting the reply from all the members but still no response...can anyone plz help me with this..anything can help me such as link or books that related with my work..TQ
     
  6. Jan 29, 2011 #5
    Re: Visible Raman

    Hi Deenaz,

    I am new in this forum, I am looking for some help in some specific problems in Raman spectroscopy.

    To answer your 3 questions, here are my answers :

    1- Yes, i think that you can use light emiting diod, but the question is what is it 's intensity? the signal may be proportional to the emiting light. Also, a simple PMT is not good, you need also a monochromator to have a spectrum (wavelength ...) if not a PMT will give you only a signal what ever is the wavelength of the detected light.

    2- the prices of the Raman spectro are so spread, from a simple portable of few thousands of euros to a whole work station with microscopy ...

    3- if you want to work on skins, i can help you, i can use my own raman to do some preliminary tests for you and see if it's okay, and if it s important to work on such instrument.

    So, just let me know if you want any help, i can help also in softwars and books.

    all my best and ... hold of strongly in your research :)

    amayas
     
  7. Feb 5, 2011 #6

    Claude Bile

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    Science Advisor

    Re: Visible Raman

    @ the Original poster;

    The Raman spectrum of a material depends (intimately) on its energy band structure (for atoms/molecules) and phonon spectrum (for solids). The relevant equations are quite complex and cannot be expressed in a simple empyrical form. If you need something to graph, I would suggest perhaps a simple harmonic oscillator for an O2 molecule or the like. Peaks in the Raman spectrum will correspond to gaps in the vibrational energy levels of the system.

    There is no fundamental reason why you can't use an LED source, however, you will lose a great deal of signal if your source is non-collimated. Since the Raman signal is typically weak this makes a laser source a must-have. There is no compelling reason to use LEDs other than cost, and lasers are pretty cheap these days, unless you need an exotic wavelength.

    You can use a PMT, though remember you are measuring a spectrum, which means you need to scan the PMT across a dispersive element. CCD arrays are a bit more convenient in this respect which is why most Raman systems use them.

    It really depends on your sample; SERS is typically used with single molecules rather than bulk samples, e.g. drug and pathogen detection. Stimulated Raman is typically used for efficient wavelength conversion, not probing the internal structure of a sample. Standard Raman ought to be suitable, at least for backscatter detection. A confocal setup might be desirable depending on whether you are getting spurious surface signals.

    I would recommend focusing slightly beneath the surface with a confocal setup to supress surface signals (Unless, of course, you want to study the surface effects!). With a Raman microscope, you can focus on different areas in the X-Y focal plane and determine structural differences; it is really dependent on what you wish to investigate.

    Claude.
     
    Last edited: Feb 5, 2011
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