NQR SPECTROSCOPY

 

NQR SPECTROSCOPY

 

NUCLEAR QUADRUPOLE RESONANCE SPECTROSCOPY

 

·         Why we use NQR Spectroscopy?

          We use NQR Spectroscopy to examine Chemical analysis. NQR transition of nuclei can be detected in the absence of magnetic filed so for this NQR Spectroscopy is referred as “Zero field NMR”.

 

Instrument of NQR Spectroscopy 

Instrument of NQR Spectroscopy

WHAT IS QUADRUPOLE AND QUADRUPOLE MOMENT.

·         Any body which is having a four poles is called a quadrupole body.

·         Quadrupole will decide the shape of a molecule that whether the Shape of a molecule is in horizontal oval (Q<0) vertical oval (Q>0).

·         Their spin quantum no. must be (I>1)

·         No. of orientation depend upon the magnitude of nuclear Quadrupole moment.

·         The NQR Spectroscopy is intermediate by the interaction of electric filed gradient.

 

Charge distribution of nucleus will tell us the shape of molecule.

the shape of molecule 

QUADRUPOLE MOMENT:

 

      Quadrupole mechanism consideration of the distribution of nuclear charge shows that nuclei do not have permanent electric dipole moment but can have electric Quadrupole moments when their electric charges are not spherically symmetric. This is usually the Quadrupole moment.

Electric filed gradient:

 

     It s the parameter which measure the rate of change of electric field in which atomic nuclei generated by the electric charge distribution nearby an electronic charge densities on the nucleus of  an atom.

·         During spectroscopy it couples the quadruple moment of nucleus with electric field gradient due to which nucleus staring to resonate.

·         That’s why we call that it is nuclear quadrupole resonance spectroscopy in which all the energy levels are generated.

·         Now in nucleus electro spinning is rise different levels.

·         To study these electrostatic interaction levels we do NQR spectroscopy.

·         They  are directly applied by nature we don’t provide it any source of UV light, X-ray beam.

·         It is fixed and particular so its is also called chemical finger print. 

 

 

MOSSBAUER SPECTROSCOPY

 

·          It’s light source is gamma δ-rays so it is also called gamma rays      resonance spectroscopy.

·          In this spectroscopy both ground state and excited state.

·          It is only occur on solid objects or a chemicals coordination    compounds.

·          The coordination compounds will be detected on the nuclear energy     levels.

 

·          All compounds are not studied by Mossbauer spectroscopy. They are   specified.

·          Sample will only absorb 14.4 eV.

 

EXAMPLE OF FE₃(C0)₁₂.

 

·         An excellent example of the use of Mossbauer spectroscopy in structure determination is provided by Fe₃(C0)₁₂. Although the dark green crystals of this compound are easy to prepare dissolve Fe(C0)₅ in aqueous alkali to give the Fe(CO)₄^-2 anion and oxidize this with solid Mn0₂ to give Fe₃(C0)₁₂^-its structure was uncertain for over 30 years Although eight structures, all incorrect, had  been proposed for  Fe₃(C0)₁₂, it was the ninth, suggested on the basis of its Mossbauer spectrum, which eventually proved to be correct. The most evident thing is that it corresponds, approximately, to three peaks of equal intensity. 

 

Mossbauer spectrum of Fe3 (C0)12