Spectroscopy depth profiling

Quantitative Auger electron spectroscopy depth profiling of iron oxides formed on Fe (100) and polycrystalline Fe by exposure to gas phase oxygen and borate buffer solution. Langmuir 6 1683-1690... 

Figure 5 Auger electron spectroscopy depth profiles of a) unused and b) used palladium membranes.

Fig. 2. Auger electron spectroscopy depth profiles for FA 49 a) exposed for 50h to environment 2 at 700°C, b) preoxidized for 16 h and exposed for 50 h to environment 1 at 700 °C...

Fig. 1 Auger electron spectroscopy depth profile of an oxygen-plasma-treated film of poly(ferrocenyldimethylsilane). The front of the image corresponds to the exposed free surface. Reproduced with permission from [4]. Copyright 2001, American Chemical Society...

Zalar, A. (1985) Improved depth resolution by sample rotation during Auger electron spectroscopy depth profiling. Thin Solid Films, 124, 223-230. 

Thirdly, the sample is etched with an Ar ion beam (5keV) in order to remove the tribofilm where it is not covered by the mask (Figure l.c). AES (Auger Electron Spectroscopy) depth profiles are performed during this operation, in order to monitor the etching process and record analytical data. Etching is stopped when the tribofilm is completely removed (Figure 2). 

AES Auger electron spectroscopy After the ejection of an electron by absorption of a photon, an atom stays behind as an unstable Ion, which relaxes by filling the hole with an electron from a higher shell. The energy released by this transition Is taken up by another electron, the Auger electron, which leaves the sample with an element-specific kinetic energy. Surface composition, depth profiles... 

SIMS Secondary Ion mass spectroscopy A beam of low-energy Ions Impinges on a surface, penetrates the sample and loses energy In a series of Inelastic collisions with the target atoms leading to emission of secondary Ions. Surface composition, reaction mechanism, depth profiles... 

As in Auger spectroscopy, SIMS can be used to make concentration depth profiles and, by rastering the ion beam over the surface, to make chemical maps of certain elements. More recently, SIMS has become very popular in the characterization of polymer surfaces [14,15 and 16]. 

Several features of ISS quantitative analysis should be noted. First of all, the relative sensitivities for the elements increase monotonically with mass. Essentially none of the other surface spectroscopies exhibit this simplicity. Because of this simple relationship, it is possible to mathematically manipulate the entire ISS spectrum such that the signal intensity is a direct quantitative representation of the surface. This is illustrated in Figure 5, which shows a depth profile of clean electrical connector pins. Atomic concentration can be read roughly as atomic percent direcdy from the approximate scale at the left. 

Roughness from sputtering causes loss of depth resolution in depth profiling for Auger Electron Spectroscopy (AES), X-Ray Photoelectron Spectroscopy (XPS), and SIMS. 

Rutherford back-scattering spectroscopy (RBS) is one of the most frequently used techniques for quantitative analysis of composition, thickness, and depth profiles of thin solid films or solid samples near the surface region. It has been in use since the nineteen-sixties and has since evolved into a major materials-characterization technique. The number and range of applications are enormous. Because of its quantitative feature, RBS often serves as a standard for other techniques. 

Chw Discharge Optical Emission Spectroscopy (CD-OES) 229 Tab. 4.2. Some typical applications of GD-OES depth-profile analysis. 

ATR infrared spectroscopy can be used to construct a depth profile showing the way in which the surface composition of a polymer changes as a function of distance away from the surface and into the polymer [3], As long as the polymer is not a very strong absorber, the absorbance of an infrared band in ATR is ... 

Fig. 12. Auger electron spectroscopy (AES) sputter-depth profile of CAA-treated titanium after various exposure.s in vacuum (a) as anodized, (b) 450°C for 1 h, and (c) 7(X)°C for 1 h. The sputter etch rate is 1.5 nm/min. The line indicates the original interface. The arrow denotes oxygen diffused into the substrate. Adapted from Ref. [51].

Surface composition and morphology of copolymeric systems and blends are usually studied by contact angle (wettability) and surface tension measurements and more recently by x-ray photoelectron spectroscopy (XPS or ESCA). Other techniques that are also used include surface sensitive FT-IR (e.g., Attenuated Total Reflectance, ATR, and Diffuse Reflectance, DR) and EDAX. Due to the nature of each of these techniques, they provide information on varying surface thicknesses, ranging from 5 to 50 A (contact angle and ESCA) to 20,000-30,000 A (ATR-IR and EDAX). Therefore, they can be used together to complement each other in studying the depth profiles of polymer surfaces. 

The film thickness and retractive index were calculated using spectroscopic ellipsometry. X-ray photoelectron spectroscopy (XPS) was used for composition analysis. Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS) was used to investigate the depth profiles of the film. 

The use of nuclear techniques allows the determination of C, N, H, O, and heavier contaminants relative fractions with great accuracy, and of the elements depth profile with moderate resolution (typically 10 nm). Rutherford backscattering spectroscopy (RBS) of light ions (like alpha particles) is used for the determination of carbon and heavier elements. Hydrogen contents are measured by forward scattering of protons by incident alpha particles (ERDA) elastic recoil detection analysis [44,47]. 

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