_process section (discharge) for electrical nanotubes

Weakening of electron transfers and the presence of dispersant when dispersing CNTs multilayered carbon nanotubes

Researcher and author: Dr. Afshin Rashid



Note: CNTs multi-layered carbon nanotubes have many impurities in some samples, such as graphene polyhedral particles, amorphous carbon and Catalyst particles.The optical absorption of these impurities is related to the spectrum and for quantitative evaluation, the field is removed. < a i=6>The assimilation of the background is necessary, which in this caseis not possible and quantitative analysis will be accompanied by errors . The third problem is caused by the presence of a dispersant, which spreads when dispersing a nanotube with multiple layers of CNTs. Its presence causes There is a mistake in the quantitative detection of SWCNT in the state 

When functional groups are covalently placed on CNTs multilayer nanotubes, absorption peaks  NIR-VIS-UV absorption spectroscopy  has two important uses: the rate of covalent reactions  and selectivity towards nanosheets /span> ) or saturation of the conduction band like (doping-n) becomes.leading to the preparation of valence electrons like (dopingPNon-covalent doping or molecular absorption different.  


These non-covalent interactions can affect the intensity of absorption peaks . When doping, electron donors such as (Cs,K) or electron acceptors very similar changes in the spectrum (- Br2) as  create NIR-vis-UV and both cause  weakening of 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  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 adsorption of nanotubes depends on (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 abundance, along with  various errors associated with data analysis, makes it  difficult to quantitatively evaluate the concentration of the special 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 . Its presence causes confusion in the quantitative detection of the amount of  SWCNTs in the state.
Researcher  and author: Dr.   (   Afshin Rashid)

Specialized doctorate in nano-microelectronics