iii. How many photons are there in a 10 ns, 2 mJ pulse of 532 nm laser light?
iv. Tetraphenylporphyrin (TPP) has a molar absorption coefficient of 4450 M$^{-1}$cm$^{-1}$
at 532 nm. TPP has a fluorescence quantum yield of 0.11. A 27 µM solution of TPP
is irradiated with a 2 µJ pulse of 532 nm laser light in a 1 cm cuvette, how many
photons are emitted as fluorescence from the sample.
(HINT: You need to calculate four things, the number of photons in the pulse, the
absorption of the sample, the number of photons absorbed and finally the number of
photons emitted as fluorescence.)
