Lifetimes of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nano second range. If the radiation source has the duration of $2 \mathrm{~ns}$ and the number of photons emitted during the pulse source is $2.5 \times 10^{15}$, calculate the energy of the source.

Question

Lifetimes of the molecules in the excited states are often measured by using pulsed radiation source of duration nearly in the nano second range. If the radiation source has the duration of $2 \mathrm{~ns}$ and the number of photons emitted during the pulse source is $2.5 \times 10^{15}$, calculate the energy of the source.,

MARKS App · Accepted Answer

Frequency $=\frac{1}{2 \times 10^{-9} \mathrm{~s}}=0.5 \times 10^9 \mathrm{~s}^{-1}$ Energy $=\mathrm{N} h v$ $\begin{aligned} &=\left(2.5 \times 10^{15}\right)\left(6.626 \times 10^{-34} \mathrm{Js}\right)\left(0.5 \times 10^9 \mathrm{~s}^{-1}\right) \ &=8.28 \times 10^{-10} \mathrm{~J} \end{aligned}$

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