The E11 * intensity of some SWCNTs directly increased stepwise after the diazonium salt was added, while others stayed unchanged for some seconds and then increased once or multiple times. These steps suggest that they represent the formation of one sp 3 defect similar to other reactions on SWCNTs . With the help of a step-fitting algorithm (see materials and methods), the defect reactions of n= 458 single SWCNTs were analyzed (Figure ). 42% of SWCNTs did not have any defect, around 36% of SWCNTs had one defect, 18% of SWCNTs had two defects, and 4% of SWCNTs had three or four defects. The percentage of defects on SWCNT was a little bit lower but similar to dlow-SWCNT (Figure , figure ) and also in agreement with the ensemble spectrum from the surface (Figure ). These differences can be attributed to the different reaction conditions. For monitoring the reaction live (figure ) the excitation light was a laser, which probably affected the effective diazonium salt concentration. The different individual onset times of the E11 * increase (figure ) cause the smooth (bulk) fluorescence increase (figure ) of all SWCNTs. When summed up, all single SWCNT step heights and quantities overlap with the bulk E11 * intensity change (figure ).