Lifetimes of the molecules in the excited state 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 ns and the number of photons emitted during the pulse source is 2.5×1015, calculate the energy of the source.
Given Data: Duration=2ns=2×10−9 seconds
Number of emitted photons =2.5×1015
Formulas to be used:
Energy =Nhω
Where N = number of emitted photons during the pulse source
h= Planck’s constant =6.626×10−34
ω=frequencyoftheradiationsource
Frequency of source=1Durationofthesource
Calculation:
Step 1: Find frequency of source
1Durationofthesource
12×10−9=0.5×109
Step 2: Substituting
N=2.5×1015
h=6.626×10−34
ω=0.5×109
In the energy formula, we get ,
Energy =(2.5×1015)(6.626×10−34)(0.5×109)=8.28×10−10 J