Comparison of mono- and polyatomic primary ions for the characterization of organic dye overlayers with static secondary ion mass spectrometry.
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 SF(5) (+) 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 SF(5) (+) 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 SF(5) (+) and Xe(+) can reach a factor of 6. In comparison with Ga(+), yield enhancements by up to a factor of 180 are observed with SF(5) (+). For the mass spectrometric analysis of dye layers on AgBr microcrystals, SF(5) (+) again proves to be the primary ion of choice.
Lenaerts
Jens
J
University of Antwerp, Department of Chemistry, B-2610 Wilrijk, Belgium.
Van Vaeck
Luc
L
Gijbels
Renaat
R
Van Luppen
Jaymes
J
D002232:Carbocyanines / Q000032:analysis*; D004396:Coloring Agents / Q000032:analysis*; D003460:Crystallization; D005708:Gallium / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D018629:Spectrometry, Mass, Secondary Ion / Q000295:instrumentation* / Q000379:methods; D013459:Sulfur Hexafluoride / Q000737:chemistry; D014978:Xenon / Q000737:chemistry
D002232:Carbocyanines; D004396:Coloring Agents; D007477:Ions; D014978:Xenon; D005708:Gallium; D013459:Sulfur Hexafluoride