Ellipsometric spectroscopy

Spectroscopic ellipsometry is a non-destructive, interface sensitive, in situ technique for interface characterization. Time resolved ellipsometric spectroscopy was used to determine the mechanism of electrochemical deposition of photoresists on copper electrodes under potentiostatic, anodic conditions. Nucleation of photoresist deposition occurs randomly. During the early stages of nucleation the semi-spherical particles are separated by about 100 A. The deposits tend to grow like "pillars" up to 50 A. Further growth of the "pillars" lead to coalescence of the photopolymer deposits. 

A smooth electrode surface for the time resolved ellipsometric spectroscopy was prepared as follows a 7059 glass slide was degreased by soaking in methanol for one hour, dried and placed in a sputter deposition chamber. High purity(99.999%) copper was sputtered in an argon atmosphere of 5 mTorr. The thickness of the copper was determined to be in the range of 4000 -4500 A. 

In ellipsometric spectroscopy, an elliptically polarized light is allowed to reflect on the interface and the change in ellipticity and phase angle are determined from complex reflectivity. 

The availability of automatic ellipsometers56 greatly helps all this. It is possible to program the ellipsometer to print a readout of, for example, refractive index and thickness as a function of potential. The technique could be applied more widely, a developmental possibility being that it could enable the operator to follow changes in spectra (and thus interpret what molecular changes cause them) in the millisecond range. One of the frontiers of development of techniques in electrochemistry could be the use of ellipsometric spectroscopy. 

Investigation of Carbon Monoxide on Nickel(lOO) by Infrared Ellipsometric Spectroscopy... 

The potential of IR ellipsometric spectroscopy (IRES) for investigating surface processes and reactions relevant to gas-solid heterogeneous catalysis is examined, both for single crystal and model dispersed catalytic systems. With it, structural and chemical changes can be followed over a wide range of temperature and gas pressure, allowing one to thermally stabilize intermediates for investigation, and study surface species under conditions close to those in practical catalytic reactions. 

EUipsometry has already been cited as the method that first established that passivity was associated with the presence of a very thin oxide film. Later it was measured (Jovancicevic, 1987) by means of ellipsometric spectroscopy and it was thus found possible to evolve an extinction coefficient that varied characteristically with the wavelength at which the ellipsometry was carried out (Fig. 12.66). The interpre-... 

There is a number of vibrational spectroscopic techniques not directly applicable to the study of real catalysts but which are used with model surfaces, such as single crystals. These include reflection-absorption infrared spectroscopy (RAIRS or IRAS) high-resolution electron energy loss spectroscopy (HREELS, EELS) infrared ellipsometric spectroscopy. 

Matz, R. and Lueth, H. Ellipsometric spectroscopy ofthe polarZnO(l 100) surface. Appl. Phys. (Berlin) 1979,18, 123-130. 

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