The broad continuous spectrum:

Formation: Electrons emitted by the heated filament are made to accelerate through a high PD before they collide with the metal target with very high speeds à interactions with the nuclei of the target atoms, thus electrons lose KE à KE lost converted to energy of x-ray photos RADIATED from the target; DIFFERENT electrons slowed to different extent à energies of x-ray photons produced take a continuous of values à continuous spectrum formed.

The sharp characteristic peak (UNIQUE for each element):

• Occurs when bombarding electron colliding with a target atom has enough energy to remove an inner-shell electron from the atom.
• Existence of Ka and Kb values: Incoming electron knocked off an electron in the n = 1 level (K-shell), in which the vacancy in this shell is then filled by an electron from the n = 2 L-shell, an x-ray photon of the Ka characteristic x-ray is emitted; For Kb, when the vacancy in the K-shell is filled by an electron dropping from the n = 3 M-shell, x-ray photon of the Kb characteristic x-ray is emitted.
• Why is the intensity of the Ka characteristic x-ray > Kb characteristic x-ray: Electrons in the n = 2 L-shell are nearer to the n = 1 K-shell, thus there is a greater probability that the vacancy in the K-shell is filled by an electron from the L-shell than the n =3 M-shell.

Other points to note for X-rays:

• Same target material –> characteristic x-rays produced have same wavelengths –> energy levels of target atoms are the same.
• Higher voltage APPLIED in x-ray tube –> minimum wavelength of x-rays produced is lower –> bombarding electrons produced by tube have higher initial KE (ß with higher voltage applied).

The broad continuous spectrum:

Formation: Electrons emitted by the heated filament are made to accelerate through a high PD before they collide with the metal target with very high speeds à interactions with the nuclei of the target atoms, thus electrons lose KE à KE lost converted to energy of x-ray photos radiated from the target; different electrons slowed to different extent à energies of x-ray photons produced take a continuous of values à continuous spectrum formed.

The sharp characteristic peak (unique for each element):

Other points to note for X-rays: