Radiation, ionizing conversion factors

Conversion Factors for Enei Units, 1-39 Conversion Factors for Ionizing Radiation,... 

Conversely, diffuaon is also a factor when a molecular species dissociates into fragments either thermally or as a result of absorption of energy due to light or ionizing radiation. 

When an atom or molecule interacts with a photon of sufficient energy, ionization may occur through removal of an electron. Because the ionization potential of most small molecules is larger than 8 eV, highly energetic photons in the VUV are required to induce ionization through one-photon absorption. Tuneable radiation may be provided by synchrotron sources and by (normally very inefficient) non-linear conversion of radiation from visible or UV lasers. However, direct one-photon ionization exhibits little state selectivity, i.e. ionization of normally several vibrational and rotational levels of the electronic ground state occurs. Consequently, in the photo-ion one also encounters a superposition of several vibrational and rotational levels (determined mostly by the Franck-Condon factors between the initial and final vibrational states). 

---