iopprofiles.blogg.se - Free xps peak fitting

Ester component tends to be of a similar intensity to C-O in adventitious carbon spectra and much weaker than C-C component.C1s carbonate component overlaps with ester (O-C=O) peak (typically present in C1s spectra of.For Group I elements, the binding energy of the C1s carbonate peak has been found to increase.The sp 3 carbon peak should be 1eV to the higher binding energy side of the sp 2 component.The sp 3 carbon and functionalized carbon should be fitted with symmetric peak shapes.Or graphene sample), including symmetric loss peaks where necessary. Fit the sp 2 component with asymmetric shape (preferably derived from a real graphite.Functionalized graphene will have a complex C1s spectrum, containing sp 2 and sp3 components.For high concentrations of sp 3-bonded carbon, the C1s peak will have a more symmetric shapeĪnd will also be slightly shifted to higher binding energy.One or more satellite features, several eV from the main C1s peak, will also be observed.The C1s spectrum from a sample with high concentration of sp 2 carbon will have a broad,Īsymmetric tail towards higher binding energy.Charge neutralization may be required, especially for functionalized graphene/graphite or diamond.C KLL acquisition conditions: Pass energy=100eV, step size=0.5eV, 100 scans, scan range.Maximizes ability to distinguish between sp2 and sp3 carbon.Acquire C1s, C KLL and valence band regions.None Graphite, Graphene, Diamond Binding energies of common chemical states: Check for presence of K2p 1/2 and K2s peaks for confirmation of potassium.π-π* satellite can be confused with potassium’s K2p 3/2 peak.π-π* satellite is seen 6eV from main C1s peak in polyethylene terephthalate, for example.Several eV to higher binding energy of the main peak. aromatic rings) can result in satellite structure, Extended delocalised electrons in a sample (e.g.C1s spectra for polymers tend to have symmetric peak components.Not always reliable, possibly changing with nature of the surface hydrocarbon, film.C-C peak at 284.8eV is frequently used a charge correction reference because of its convenience.Polymer materials containing F or Cl are often degraded by Ar+ monomer sputtering with loss of F or Cl.Some polymers may be sputtered successfully with 200eV argon monomers.Argon cluster source preferred for depth profiling of polymers.Charge neutralization will be required.

Good method for analyzing self-assembled monolayers.Statistics) but the amount of X-ray damage at each individual is negligible. Overall acquisition time is then the sum of every point (giving good signal-tonoise.If the sample surface is chemically uniform, it may be preferable to rapidly acquire dataįrom many points and then integrate the data post-acquisition.Acquire regions of interest first (e.g., C1s, O1s) before running survey, if possible.C1s regions for polymers can often have acquisition times of Different polymers have different degradation rates.

Some polymers are sensitive to prolonged X-ray exposure.

Particularly useful in cases where C1s XPS data cannot easily distinguish between.

Acquisition of valence band can be useful for “fingerprint” identification of polymers.

Polymers Binding energies of common chemical states:

Inelastic scatter of electrons through the adventitious carbon layer may cause a largeĬhange in background shape when compared with the spectrum from a clean sample.

For example, the Na1s peak (binding energy=1071eV) may be weaker thanĮxpected, or completely disappear, but the Na KLL peak (binding energy=497eV).

The intensity of higher binding energy peaks may be reduced relative to their.

Quantification may be inaccurate when using peaks of significantly different energy.

On native oxide of aluminium appears at ~286eV).Ī few nanometers of adventitious carbon on a sample can dramatically affect the survey

Not always a valid charge reference value (e.g.

The C-C component may be set to a binding energy of 284.8eV, by default.

C1s spectrum for contamination typically has C-C, C-O-C and O-C=O components.

Prevent/minimize chemical damage to the underlying material.Īdventitious carbon contamination is commonly used as a charge reference for XPS spectra.

Use lowest energy argon beam available (e.g.

Adventitious carbon may be removed by argon sputtering.

(Typically with a layer thickness of 1-2nm.)

Most samples that have been exposed to the atmosphere will have a detectable quantity ofĪdventitious carbon contamination.

Carbonates and Carbides)Īdventitious Carbon Contamination Binding energies of common chemical states:Ĭharge referenced to adventitious C1s, C-C peak at 284.8eV Experimental Information