Isotopic separation by photopredissociation

A monochromatic source may be used to excite individual isotopic lines in a well-resolved absorption spectrum for which the upper state is predissociated. Isotopic enrichment is thus achieved in the dissociation products, which may be stable molecules or may be chemically trapped if they are reactive. As an example, isotopic separation of hydrogen and deuterium is performed by exciting formaldehyde with a frequency-doubled ruby laser.