Introductory Theory and Terminology
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Figure3.13: Decoupling Experiment
Figure3.14: Ethylbenzene Spectrum with Homodecoupling
The experiment described above is an example of homodecoupling in that the same isotope,
namely 
1
H,  is  observed  and  decoupled.  Heterodecoupling  is  where  the  isotope  to  be
observed  is  different  to  that  which  is  decoupled.  In  the  chapter  ¹³C  Spectrum  with  Proton
Decoupling [}67] of this manual you will perform a heterodecoupling experiment where you
observe 
13
C  and  decouple 
1
H.  AVANCE  spectrometers  have  the  ability  to  perform  very
complicated types of experiments depending  upon  the number  of channels installed.  A four
channel spectrometer can be used to observe one nucleus and decouple three other nuclei.
With up to eight  independent  channels the  possible range  of experiments  is  quite amazing.
The  user  should  be  aware  that  currently  the  limiting  factor  is  not  in  the  generation  of  RF
excitation and decoupling pulses but in transmitting these pulses to the sample via the probes
and to some extent the preamplifiers. The signal routing of the experiment to be carried out is
set  up  using  the  "edasp“  menu.  More  details  can  be  found  in  the  manual  “Acquisition
Commands and Parameters” (P/N H9775SA3).