code: private static IAtomContainer initiateIonization(IAtomContainer container, IAtom atom) throws CDKException {
          IReactionProcess reactionNBE = new ElectronImpactNBEReaction();
  
          IAtomContainerSet setOfReactants = container.getBuilder().newInstance(IAtomContainerSet.class);
          setOfReactants.addAtomContainer(container);
  
          atom.setFlag(CDKConstants.REACTIVE_CENTER, true);
          List<IParameterReact> paramList = new ArrayList<IParameterReact>();
          IParameterReact param = new SetReactionCenter();
          param.setParameter(Boolean.TRUE);
          paramList.add(param);
          reactionNBE.setParameterList(paramList);
  
          /* initiate */
          IReactionSet setOfReactions = reactionNBE.initiate(setOfReactants, null);
          atom.setFlag(CDKConstants.REACTIVE_CENTER, false);
          if (setOfReactions != null && setOfReactions.getReactionCount() == 1
                  && setOfReactions.getReaction(0).getProducts().getAtomContainerCount() == 1)
              return setOfReactions.getReaction(0).getProducts().getAtomContainer(0);
          else
              return null;
      }
docs: Initiate the reaction ElectronImpactNBE.
  
  @param container The IAtomContainer
  @param atom      The IAtom to ionize
  @return          The product resultant
  @throws CDKException