Atomic Structure and Electron Interactions

Question 1

Describe electron volt

Answer 1

Energy required to raise an electron through a potential difference

Question 2

Describe binding energy

Answer 2

Energy required to hold the electron in its shell, or to remove it

Question 3

Describe the keV

Answer 3

Peak potential applied to the X-ray tube

Question 4

Name the types of electron interactions

Answer 4

Elastic and inelastic

Question 5

Describe elastic electron interactions

Answer 5

Kinetic energy conserved
Electron interacts with orbiting electron
–> deflected without losing energy

Question 6

Describe inelastic electron interactions

Answer 6

Some or all energy given to target
Kinetic energy lost from incoming electrons
–> excitation and/or ionisation of target atoms
–> x-ray photon

Question 7

Describe elastic scattering

Answer 7

Closer the electron travels towards nucleus, greater amount of deflection

Question 8

Describe Ionisation

Answer 8

Process by which an atom becomes positively or negatively charged
(gaining or losing electrons)

Question 9

Describe some differences between characteristic and bremsstrahlung radiation

Answer 9

Characteristic - requires 70 kVp or higher
Bremsstrahlung - produced at any energy

Question 10

How much energy is converted to thermal?

Answer 10

99%

Question 11

In xray beams, how much is bremsstrahlung and how much is characteristic?

Answer 11

Bremsstrahlung - 90%
Characteristic - 10%

Question 12

Describe Bremsstrahlung

Answer 12

Incoming electron passes by close to atom nucleus
Nucleus is + so electron changes direction and loses energy in form of x-ray photon
Energy loss causes electron to slow

Question 13

Describe Characteristic radiation

Answer 13

Incident electron collides with orbiting k electron
Incident electron changes direction and orbital electron is ejected
Electron from L or M moves to vacancy, excess energy given off as photon