Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. Finally, the electrons recombine with holes under emission of photons. Adsorbed hydrogen species recombine to form hydrogen molecules, creating pressure from within the metal. Sequences may also recombine or be deleted due to chromosomal rearrangements. Often the electrons recombine with the holes without reaching the electrode. After ionization, the electron and proton recombine to form a new hydrogen atom. Some of the ionized molecules then recombine as O, ozone. The largest repeats recombine regularly and isomerize the genome. Some of these electrons do not recombine and escape to the underlying n-region (step 2). Electron-hole pairs are also apt to recombine. When vacancies collide with interstitials (Frenkel), they can recombine and annihilate one another. An ion and an electron can recombine and produce electronic-neutral products. When the hydrogen cools sufficiently to recombine, the outer layer becomes transparent. When an electron meets with a hole, they recombine and these free carriers effectively vanish. It is very rare for organelle genes from different lineages to recombine.