Role of photoionization and photochemistry in ionization processes of organic molecules and relevance for matrix-assisted laser desorption lonization mass spectrometry

✍ Scribed by H. Ehring; M. Karas; F. Hillenkamp

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 986 KB
• Volume: 27
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210270419

✦ Synopsis

The ionization in ultraviolet laser desorption was investigated for a large number of small polar organic molecules which have a strong resonance absorption at the laser wavelength. In many cases, both positive-and/or negative-ion mass spectra show strong signals of ion species which deviate from the simple scheme of even-electron quasi-mo\ecular and fragment ion formation commonly expected for desorption techniques. These are radical cations and ion species formed by single and multiple hydrogen cleavage or addition. A model is proposed and discussed which explains these features assuming photoionization as the common initial ionization step followed by ion-molecule reactions to the final product ions. The mass spectra of all compounds proved to function well in matrix-assisted ultraviolet laser desorptionfionization show characteristic features indicative of their photochemical reactivity. This observation substantiates the hypothesis of the essential role of the matrix in analyte ionization