What does t2-t1 represents in the expression t2-t1 = RC*ln|9|?
I think t2-t1 is the rising time


Yes, t2-t1 on your handwritten diagram (not on your scope trace) is the rise time of the signal (sometimes written as Tr).

I have found some problems, which I've marked on a copy of your notes:



Looking at the red numbers which I added to your photo:


The formula you are using is for a series RC network, but your schematic shows a parallel RC network. That's why you are not seeing the expected waveform shape.
In your rise time calculation, 0.00022 isn't 220ms as you wrote; it's 220us.


Also, the markings of t2 and t1 on your scope image are incorrect - you seem to be trying to find those points on your scope trace, but that trace isn't showing the expected waveform due to problem "1" which I explained above.

Summary: Change it to a series RC network, measure the voltage across the capacitor with your scope, and you should see approximately 220us rise time (Tr), which matches your calculation.