Quantum Mechanics – Selection Rules

Which of the following is NOT compatible with the selection rule that controls electric dipole emission of photons by excited states of atoms?

A. ∆n may have any negative integral value
B. ∆l = ±1
C. ∆m_l = 0, ±1
D. ∆s = ±1
E. ∆j = ±1

(GR8677 #92)

Solution:

Selection rules:

1.	Principal quantum number	:	∆n = anything
2.	Orbital angular momentum	:	∆l = ±1
3.	Magnetic quantum number	:	∆ml = 0, ±1
4.	Spin	:	∆s = 0
5.	Total angular momentum	:	∆j = 0, ±1, but j = 0 ↛j = 0

Answer: D