The potential energy of a magnetic moment in an externalmagnetic field is U = - ??B. U is smallest when B is parallel to ?and largest when it is antiparallel. Since the magnetic moment ofthe electron is directed opposite to its spin (because it has anegative charge), the electron’s energy is highest when the spin isparallel to B. The two possible energy states for the electron arethe spin up state (ms = 1212) and the spin down state(ms = - 1212). Calculate the energy difference ?E (ineV) between these states if the electron is placed in a magneticfield of B = 1.1 T. Assume that n = 10 and l = 0 for theelectron.
If these electrons are bombarded with photons that have anenergy equal to this energy difference ?E, then the electrons canbe excited from the spin down state to the spin up state. This isreferred to as a “spin flip†transition and the technique is calledElectron Spin Resonance (ESR). Find the wavelength of the photons(in meters) that are needed to excite such spin fliptransitions.
What type of electromagnetic wave has this wavelength?
