Comparison of mono- and polyatomic primary ions for the characterization of organic dye overlayers with static secondary ion mass spectrometry

• Published in: Rapid communications in mass spectrometry 2004-01, Vol.18 (3), p.257-264
• Main Authors: Lenaerts, Jens, Vaeck, Luc Van, Gijbels, Renaat, Luppen, Jaymes Van
• Format: Article
• Language: English
• Subjects: Carbocyanines - analysis; Coloring Agents - analysis; Crystallization; Gallium - chemistry; Ions - chemistry; Spectrometry, Mass, Secondary Ion - instrumentation; Spectrometry, Mass, Secondary Ion - methods; Sulfur Hexafluoride - chemistry; Xenon - chemistry
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.1320

Organic carbocyanine dye coatings have been analyzed by time‐of‐flight static secondary ion mass spectrometry (TOF‐S‐SIMS) using three types of primary ions: Ga+ operating at 25 keV, and Xe+ and SF5+ both operating at 9 keV. Secondary ion yields obtained with these three primary ions have been compared for coatings with different layer thickness, varying from (sub)‐monolayer to multilayers, on different substrates (Si, Ag and AgBr cubic microcrystals). For (sub)‐monolayers deposited on Ag, Xe+ and SF5+ primary ions generate similar precursor ion intensities, but with Ga+ slightly lower precursor ion intensities were obtained. Thick coatings on Ag as well as mono‐ and multilayers on Si produce the highest precursor and fragment ion intensities with the polyatomic primary ion. The yield difference between SF5+ and Xe+ can reach a factor of 6. In comparison with Ga+, yield enhancements by up to a factor of 180 are observed with SF5+. For the mass spectrometric analysis of dye layers on AgBr microcrystals, SF5+ again proves to be the primary ion of choice. Copyright © 2004 John Wiley & Sons, Ltd.