Weakening of electron transfers and the presence of dispersant when dispersing multi-layered carbon nanotubes and CNTs

Note: CNTs multilayer carbon nanotubes in some samples have many impurities,  such as polyhedral graphene particles, amorphous carbon and  catalyst particles. The optical absorption of these impurities  is related to the spectrum and for quantitative evaluation it is necessary to remove  the absorption background  , which is not possible  in this case  and the quantitative analysis will be accompanied by errors. The third problem is caused by the presence  of a dispersant that spreads  when dispersing  the multi-layered nanotubes of CNTs, which causes confusion in the quantitative detection of the amount of  SWCNTs in the state.

When  the functional groups are covalently  placed on CNTs multilayer nanotubes, the absorption peaks  are clearly weakened or even  disappear because the structure of nanotubes in some  six-sided SP2 is changed  to the structure  of parts of SP3 structure  . NIR-VIS-UV absorption spectroscopy  has two important uses: the rate of  covalent reactions and selectivity towards  different nanoparticles.  Non-covalent doping or molecular absorption  leads to the preparation of valence electrons (doping P ) or conduction band saturation  (doping-n).

These non-covalent interactions  can affect the intensity of absorption peaks  . During doping, electron  donors such as (Cs, K) or electron acceptors  produce  very similar changes in the spectrum  (-Br2 ) such as  NIR-vis-UV and both weaken electron transfers.  Absorption spectroscopy should be used to estimate the abundance of  metal and semiconductor species by comparing  the intensity of the corresponding peaks;  Because the position of these resonance peaks  depends on the chirality and diameter. For  qualitative analysis, absorption spectroscopy is excellent because  it shows the overall composition of the sample;  But the quantitative evaluation depends on several possible reasons  for the adsorption of nanotubes to (m,n)  .

The ratio of extinction coefficients for metal-to-semiconductor SWCNTs  is reported to  be +0.352, which should be independent of  -0.009 separation method or starting materials. But the  extinction coefficient values ​​of SWCNTs reported in  scientific sources are not consistent, and better measurement methods are still  needed to determine the extinction coefficient  of different (m,n) nanotubes. Secondly,  the strong π absorption in the short wavelength region causes  that the resonance transitions are not separate.  In addition, the complexity related to the overlap  of the peaks is problematic. As a result, the existence of a large number of SWCNTs with  different (m,n) with unknown frequency, along with  various errors associated with data analysis, makes it  difficult to quantitatively evaluate the concentration of the specific species  (m,n) in the sample, and only estimated data  It comes

Conclusion:

CNTs multilayer carbon nanotubes in some samples have many impurities,  such as polyhedral graphene particles, amorphous carbon and  catalyst particles. The optical absorption of these impurities  is related to the spectrum and for quantitative evaluation it is necessary to remove  the background absorption background  , which is not possible in this case  and the quantitative analysis  will be accompanied by errors. The third problem is caused by the presence  of a dispersant that spreads  when dispersing  the multi-layered nanotubes of CNTs, which causes confusion in the quantitative detection of the amount of  SWCNTs in the state.