# Homework Help: Spectroscopy (Molecular,Microwave)

1. Mar 23, 2013

### Klestine

1. The problem statement, all variables and given/known data
The bond length of CO is 1.128 Å. At what wavenumbers do the first three rotational transitions appear

2. Relevant equations
μ= (m1m2/m1+m2)
I = μr0^2
B= h/(8∏^2)IbC
ΔE = 2B (J+1)

3. The attempt at a solution

For the first equation I got

(12 x 16) / 28 = [(6.857 /1000)/ avagadro number] = 1.138 x 10^-26

For the second equation I got

(1.138 x 10^-26) x (1.128 x 10^-10)^2 = 1.44 x 10^-46 kg/m^2

For the third equation I got

planck's constant / [(8∏^2) x (1.44 x 10^-46 ) x (speed of light)] = 1.93cm^-1

really appreciated and thank you very much

2. Mar 25, 2013

### Staff: Mentor

You're doing fine. What about the fourth equation you listed?

3. Mar 25, 2013

### Klestine

Thats the problem, I know the answer is in that equation but I just do not know how to use it to get the values for the first 3 rotational energy levels. Just don't know to tackle that equation.Thanx for the reply