Recent content by photon79

  1. P

    Another Raman spectrum question!

    Now its much clear to me. My question was "How can we absrove rotations and/or vibrations in Raman spectra where we use visible source?" Here what happens is molecule is excited to a virtual state (as Gokul said)say 20,000 Cm-1 which is in visible and scattered at lower vibrational say, 19,000...
  2. P

    P,Q and R branches!

    Hi claude...thanks for the replies, I got some thing out of them,.
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    Spectroscopy Discussion Thread

    Thank you Gokul,,but I have exam on 7th so if possible please reply to my specrtoscopic threads (also those regarding P,Q,R branches in solidstate forum, if you want I'll post them again here) as soon as possible. Just give small and adequate replies and then we can continue on the regular...
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    Split from Spectroscopy Discussion Thread

    A laser in visible is used in Raman spectroscopy and the resultant spectrum is in IR and Microwave region(which means molecular vibrations and rotations are excited), what type of interaction is this that induces these levels? ( I cannot think more than..."To be Raman active molecules should...
  5. P

    Another Raman spectrum question!

    Yes, but my question is how vibration can be escited during the scattering? (As the source used is visible, I think some basic understanding is missing from my side)
  6. P

    Another Raman spectrum question!

    Thank you inha! My question is How this inelastic scattering of visible light excites rotations or vibrations ?
  7. P

    Another Raman spectrum question!

    A laser in visible is used in Raman spectroscopy and the resultant spectrum is in IR and Microwave region(which means molecular vibrations and rotations are excited), what type of interaction is this that induces these levels? ( I cannot think more than..."To be Raman active molecules should...
  8. P

    Raman spectroscopy is Single molecule identification

    Ok , Thanks Gokul! I dodn't get what scattering cross section has to do with molecule identification, more info please! (or any web site?)
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    Raman spectroscopy is Single molecule identification

    That is what I want to know,i think it is not same as you said but it is connected with the Surface enhanced Raman spectroscopy(I think). It might be identifying a given unknown sample using info about its symmetry !!!!!!
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    P,Q and R branches!

    In rotational-vibrational spectroscopy P-branch corresponds to low level rotational transitions "delta J = -1" and R-branch to high rotations "delta J = +1". And I am confused about Q branch which corresponds to "delta J = 0" ; which means that no rotational change is there and it is allowed in...
  11. P

    Raman spectroscopy is Single molecule identification

    Thnks inha,,you are right, I was looking in laser excitations.
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    Raman spectroscopy is Single molecule identification

    Raman spectroscopy is "Single molecule identification" Hi , I heard that the speciality of Raman spectroscopy is "Single molecule identification", it'd be really great if somebody can tell me HOW! because its surely going to be a question in my exam!! Thanks in advance.
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    Metallic bonds

    Electrons which have more energy(K.E) will form CB and electrons with lower energy will create VB. CB is nothing but space where electrons are more mobile hence conductive and in VB they are somewhat bound. I suggest some readings on solidstate physics from Richard Bube(Electrons in solids) or...
  14. P

    Si and light

    To speak more of this, there are semiconductors with Direct band gaps and Indirect band gaps. In direct band gap materials optical transitions are more probable eg:- GaAs. Here valance band maximum and conduction band minimum lie at same K-value. Where as in indirect band gap materials...
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    Metallic bonds

    conduction band is NOT EMPTY. There are carriers(electrons in general) which are mobile. . Also for nonmetals in all cases does the valenece band overlap the conductive band? For metals valance and conducton bands are merged i.e for conductors. (note that som times distinction between...
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