Appearance size and appearance energy of doubly and triply charged ammonia clusters

✍ Scribed by P. Scheier; G. Walder; A. Stamatovic; T.D. Märk

• Publisher: Elsevier Science
• Year: 1988
• Tongue: English
• Weight: 461 KB
• Volume: 150
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(88)80031-9

✦ Synopsis

Multiply charged ammonia clusters are produced by electron impact ionization of neutral NH, clusters formed by nozzle cxpansion. The properties of these ions are studied with a high-resolution double-focusing sector field mass spectrometer. The observed critical appearance sizes are n, = 5 I and n, = I2 1 for doubly and triply charged clusters, respectively. The appearance energy of doubly and triply charged ammonia clusters is found to be shifted way below the respective appearance energy of the monomer. This is in accordance with a recently suggested sequential ionization mechanism for the production of stable multiply charged van der Waals cluster ions.