ionization energy

Examples of ionization energy in the following topics:

• Thermal Distributions of Atoms

  • Atoms generally have a certain ionization energy (for example, hydrogen has 13.6~eV) but there are an infinite number of states between the ground state and the ionization level so $e^{-\beta E_i}$ approaches a constant for large $i$ and $g_i$ typically increases so $U$ will diverge.

• Radiation Detection

  • A radiation detector is a device used to detect, track, or identify high-energy particles.
  • Modern detectors are also used as calorimeters to measure the energy of detected radiation.
  • Gaseous ionization detectors use the ionizing effect of radiation upon gas-filled sensors.
  • If a particle has enough energy to ionize a gas atom or molecule, the resulting electrons and ions cause a current flow, which can be measured.
  • Scintillators can also be used in neutron and high-energy particle physics experiments, new energy resource exploration, x-ray security, nuclear cameras, computed tomography, and gas exploration.

• Bound-Free Transitions and Milne Relations

  • We would also like to understand bound-free transitions or ionization.
  • We know that by conservation of energy that the electron final momentum must satisfy
  • Because the energy of the outgoing electron is much greater than the binding energy of hydrogen it is safe to assume that
  • We can improve upon the assumption that we made that the electron's energy is much greater than the ionization energy by using Coulomb wavefunctions which are solutions to the Schrodinger equation for positive (i.e. continuum) energy values.
  • The total cross-section for a photon of frequency $\omega$ to ionize an electron from a hydrogenic atom in state $n$ is

• Problems

  • How much energy does a photon need to ionize the following atoms by removing a K-shell electron?
  • Using the formula that I derived in class, draw an energy diagram that shows the total cross section for one gram of gas as a function of energy between 10eV and 10keV.

• Ultraviolet Light

  • Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, that is, in the range 10 nm to 400 nm, corresponding to photon energies from 3 eV to 124 eV (1 eV = 1.6e-19 J; EM radiation with frequencies higher than those of visible light are often expressed in terms of energy rather than frequency).
  • Most ultraviolet is classified as non-ionizing radiation.
  • The higher energies of the ultraviolet spectrum from wavelengths about 10 nm to 120 nm ('extreme' ultraviolet) are ionizing, but this type of ultraviolet in sunlight is blocked by normal molecular oxygen (O2) in air, and does not reach the ground.
  • These properties derive from the ultraviolet photon's power to alter chemical bonds in molecules, even without having enough energy to ionize atoms.
  • After atmospheric filtering, only about 3% of the total energy of sunlight at the zenith is ultraviolet, and this fraction decreases at other sun angles.

• Radiation from Food

  • Food irradiation is a process of treating a food to a specific dosage of ionizing radiation for a predefined length of time.
  • Food irradiation is a process of treating a food to a specific dosage of ionizing radiation for a predefined length of time.
  • They also permit dose uniformity, but these systems generally have low energetic efficiency during the conversion of electron energy to photon radiation, so they require much more electrical energy than other systems.
  • Still, there is some controversy in the application of irradiation due to its novelty, the association with the nuclear industry, and the potential for the chemical changes to be different than the chemical changes due to heating food (since ionizing radiation produces a higher energy transfer per collision than conventional radiant heat).
  • Food and Drug Administration regulations to show a food has been treated with ionizing radiation

• X-Rays

  • X-rays are electromagnetic waves with wavelengths in the range of 0.01 to 10 nanometers and energies in the range of 100 eV to 100 keV.
  • X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds.
  • This makes it a type of ionizing radiation and thereby harmful to living tissue.
  • The ionizing capability of X-rays can be utilized in cancer treatment to kill malignant cells using radiation therapy.
  • X-rays with photon energies above 5 to 10 keV (below 0.2-0.1 nm wavelength), are called hard X-rays, while those with lower energy are called soft X-rays.

• Gamma Rays

  • Gamma rays from radioactive decay are defined as gamma rays no matter what their energy, so that there is no lower limit to gamma energy derived from radioactive decay.
  • Gamma decay commonly produces energies of a few hundred keV, and almost always less than 10 MeV.
  • Gamma rays are ionizing radiation and are thus biologically hazardous.
  • Astrophysical processes are the only sources for very high energy gamma rays (~100 MeV).
  • All ionizing radiation causes similar damage at a cellular level, but because rays of alpha particles and beta particles are relatively non-penetrating, external exposure to them causes only localized damage (e.g., radiation burns to the skin).

• Problems

  • Calculate the energy and wavelength of the hyperfine transition of the hydrogen atom.
  • You may use the following formula for the energy of two magnets near to each other
  • Calculate the energy and wavelength of the transition of hydrogen with the spin of the electron and proton aligned to antialigned.
  • Calculate the ionized fraction of pure hydrogen as a function of the density for a fixed temperature.

• B.8 Chapter 8

  • Calculate the energy and wavelength of the hyperfine transition of the hydrogen atom.
  • You may use the following formula for the energy of two magnets near to each other
  • The spins can be aligned or antialigned so the energy difference is $2 \mu_1 \mu_2 / r^3$ so we get
  • Calculate the ionized fraction of pure hydrogen as a function of the density for a fixed temperature.