In: Physics
A dye molecule has electrons that are free to travel up and down a chain of atoms, giving electron energy states that are given by the particle-in-a-box model, with En=(0.34eV)n2. What are the three longest wavelengths of visible light that the molecule will absorb?
The visible spectrum of light range from 380nm to 740 nm.
Energy states for particle in a box is given by :
Let n1= 1
hc = 1240 nm eV
n22 = 2.016/ 0.34 = 6.194
n2= 2.488
So to find the longest wavelength,
let n2 = 3 and n1 =2
0.34 ( 9-4) = 1240 /
1.7= 1240/
= 729.411 nm=
this is the longest wavelength absorbed in visible light.
Similarly we can calculate wavelength for (b) n2 = 4 and n1
=3 = 521 nm
(c) n2 =5 and n1 = 4 = 405.288
nm