Formation of protonated ammonia cluster ions: Two-color two-photon ionization study

Fuminori Misaizu, Paul L. Houston, Nobuyuki Nishi, Hisanori Shinohara, Tamotsu Kondow, Minoru Kinoshita

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


The mechanism of the resonance-enhanced two-photon ionization (RE2PI) and the dissociation of ammonia clusters has been investigated by using the two-color ionization technique and the reflectron time-of-flight mass spectrometer. The clusters are firstly excited to the intermediate state corresponding to the à 1A2 state of an ammonia molecule. The lifetime of the intermediate species is found to be < 10 ns for the production of NH4+ and (NH3)2+, and longer than 1 μs for (NH3)nNH4 + (1≤n≤6). This result implies that NH4+ is produced by the ionization of the dimer followed by the dissociation of NH2, whereas the higher protonated cluster ions are produced by the second photon ionization of the (NH3)nNH4 radicals produced by the dissociation of the parent clusters in the intermediate state. The appearance potentials of (NH3)2+ and (NH3)nNH4+ (0≤n≤4) are also determined by two-color RE2PI technique. Those values are discussed in connection with the two possible mechanisms for the observed ion production, which confirms the scheme obtained from the lifetime measurement.

Original languageEnglish
Pages (from-to)336-341
Number of pages6
JournalJournal of Chemical Physics
Issue number1
Publication statusPublished - 1993


Dive into the research topics of 'Formation of protonated ammonia cluster ions: Two-color two-photon ionization study'. Together they form a unique fingerprint.

Cite this