Selective ionization of photofragments using tunable radiation from a synchrotron

We report time-of-flight spectra of fragments from photodissociation of various molecules using tunable radiation from a synchrotron for ionization. Ionization energy, population of electronic states, and distribution of internal energy of products result in varied quantum yields for ionization. We successfully used soft photoionization to detect, among other species, atomic D, O (1D), HCOH and CH2 (a˜A11) without interference from H2, O (3P), CH2O and CH2 (X˜B13), respectively.