XPS studies of coablt phthalocyanine thin films
EMSL Project ID
8992
Abstract
Dense well-ordered monolayers of cobalt(II) phthalocyanine, CoPc, on Au(111) have been made and studied by our group using XPS, UPS, and STM. These films have all been grown by thermal deposition in vacuum. Recently, we have discovered a method of depositing dense well-ordered monolayers from fluid solution using a surface specific redox reaction. In this process, an ionic alkali halide saltof the anion CoPc(CN)2 is dissolved in ethanol and exposed to a gold surface. Within a short time, a dense non-ionic layer free of alkali metal forms on the surface. Based on preliminary XPS, and upon surface Raman and OMTS studies, we believe that the reaction product is CoPc. In order to further confirm this, we wish to perform high resolution XPS measurements in order to ascertain 1) the oxidation state(s) of cobalt and 2) the Co/N ratio of the adlayer. As a control, we also wish to make the same measurements on an authentic CoPc/Au sample. An additional experiment will be to measure the Cs region of the XPS spectrum to further confirm that no Cs from the CsCoPc(CN)2 strarting material, is present.These are straightforward XPS measurements, but will take some time because of the very low surface concentration of the elements studied. A monolayer of CoPc has only one cobalt and 8 nitrogen atoms per 3 nm2. Based on our experience here at WSU, we would expect to need from 30 to 48 hours of instrument time using monochromatic X-ray excitation. Moreover, because the compound slowly decomposes in the X-ray beam, several spots will have to be used when averaging data.
It is our expectation that a graduate student, Mr. William English, will bring the samples to PNL and participate in the measurements. Mr. English has performed these types of experiments using our Kratos 165, and can be given as much independence as you are comfortable in giving.
Why aren't we using our instrument? Because it is broke and will take 3-4 weeks to repair, and because we need the data to complete a paper. We are in a hurry!
Project Details
Project type
Exploratory Research
Start Date
2004-05-04
End Date
2006-04-18
Status
Closed
Released Data Link
Team
Principal Investigator
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