Spectroscopic ellipsometry of interfacial phase transitions by Dogel S.

By Dogel S.

The research of the interfacial part transitions in fluid structures with short-range intermetallic interactions are of serious curiosity. The phenomena have been studied in platforms displaying a liquid-liquid miscibility hole: on the fluid/wall interface in fluid KxKCl1-x and on the fluid/vacuum interface of the Ga1 xBix alloys. To signify the interfacial adjustments of the extremely skinny movies (composition, thickness and their evolution with time) the spectroscopic ellipsometry was once played over a large spectral diversity. while within the experiments on KxKCl1-x an latest ellipsometer might be used, a very new UHV-apparatus together with the in-situ section modulation ellipsometer needed to be built for Ga1 xBix alloys. For the KxKCl1-x method new effects on whole wetting at solid-liquid coexistence in addition to within the homogenous liquid part (prewetting) are provided. The spectra express the common F middle absorption which shows that the movie is a salt-rich section. The thickness strongly raises impending the monotectic from 30 to 440 nm, that is in contract with the tetra aspect wetting situation. For this interpretation a quantitative description of the surplus Gibbs strength has been constructed. For the Ga1 xBix procedure the implications on whole wetting, floor freezing and oscillatory interfacial instabilities are offered. The high-precision spectra were recorded drawing close the liquid-liquid miscibility. those spectra were modeled utilizing a Ga-Bi potent medium approximation for the substrate coated by means of a movie of liquid Bi. The measurements provide proof of tetra element wetting within the Ga-Bi approach. First ellipsometric learn of the outside freezing in Ga-Bi has been played. in the miscibility hole a truly attention-grabbing impression of floor and bulk oscillatory instability was once saw. the main points of this approach at the moment aren't good understood, yet a qualitative description is given.

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Additional resources for Spectroscopic ellipsometry of interfacial phase transitions in fluid metallic systems: KxKCl1-x and Ga1-xBix

Example text

2, Nr. 6). 35 UHV chamber for in-situ measurements of liquid Ga-Bi alloys 1 3 4 5 2 6 7 Fig. 1 Frontal cut of the chamber: 1, 5 – modulator and analyser heads of UVISEL modulation ellipsometer; 2, 4 – low-stress windows; 3 – liquid nitrogen trap; 6, 7 – alignment mechanisms. For details see the text. There are two observation windows from quartz on CF40 flanges on the front side of the chamber. Whereas all flanges of the apparatus have been sealed using standard copper-rings 36 Chapter 4 (CF gaskets), a special technique has been applied to achieve UHV sealing of the quartz window on the metal flange [Noble94].

The ellipsometer has no mechanically moving parts; hence it does not produce vibrations. It possesses rapid and high precision data acquisition, which makes it principally insensitive to vibrations from different sources. Coming to the alignment and calibration, a few words should be said about the operations made during the manufacturing and testing of the instrument at Jobin Yvon Company. These are: the calibration of the modulation amplitude A and electronic calibration. During the first one, J0(A) is set equal zero and during the second, the factors correcting the birefringence of the modulator and the electronic bandpass are determined [Drevillon82].

This value nicely agrees with the wavelength of 450 nm used in this measurement. That is why the interference conditions are fulfilled every 450 nm of the height variation on cooling. Disregarding the periodical variation, the overall stability of the 50 Chapter 5 reflectivity upon temperature variation of 20 K is very good. The described periodical change could be sometimes seen in the ellipsometric angles Ψ and ∆ (not shown here). u. 0 Time / hours Fig. 01 alloy ({) as a function of time (crucible temperature).

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