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Contact Angle and Surface Tension Determination Service
Scientific Responsibles Dra. Carmen López Santos
Advanced characterization of wetting using a goniometer to determine the contact angle of liquid droplets deposited on a surface is a quantitative and non-destructive analysis technique in general, depending on the surface reactivity with the wetting liquid. The combination of several liquids allows to determine the surface tension of the wet solid and to estimate the work of adhesion in simulated environments. The control of the wettability of smart surfaces under the action of external stimuli such as the application of light, temperature and/or humidity gradients, changes in pH or electric fields, are of great interest in advanced applications for the aeronautical industry, lines of communication, transportation, protection, heritage, solar and wind energy or biomedicine, among others.
Determination of the contact angle is carried out by applying Young's equation for interfacial tension balance, with sensitivity at the nanometric scale. The tests can be carried out in static or in dynamic modes to obtain hysteresis (advanced and receding angle values) of surfaces and critical values of droplet sliding. Regarding the surface tension of the solid surface, implemented theoretical models are those of Owens, Wendt, Rabel and Kaelble, Extended Fowkes, Schultz and Van Oss&Good and Neumann, based on the existence of polar and dispersive components. In addition, the temporal tracking of the surface contact angle accounts for aging and stability in certain environments. Finally, the assistance of a controlled temperature and humidity chamber allows studies of condensation/evaporation and freezing/thawing of water on surfaces.
The contact angle and surface tension measurement equipment has been supported by the Junta de Andalucía (Aid for R&D infrastructure and equipment 2019-PAIDI2020 European Regional Development Fund)
Available Equipment
DataPhysics OCA 25 Optical Contact Angle Goniometer, consisting of::
- double injection system with liquid drop volume, between nanoliters (close to the state of the art) to tens of microliters, controlled by a magnetic valve for dispensing
- TBU100 tilting platform for studies of droplet sliding on the surface (-5º - 95º)
- sample holder base adjustable in 3 spatial directions
- TPC160 thermoelectric module for temperature control (from -30ºC to 150ºC)
- module for the application of electric field EWP100 in studies of wetting electrostimulation (0-64kV DC/AC, 3-10mm electrode distance)
- HGC30 electro-humidification chamber to control the humidity of the environment (from 5% to 90%)
- SCA 21 software with routine for surface tension estimation (0.01-2000 mN/m)
- front (3250 f/s) and vertical (2450 f/s) optical systems
Contact
mclopez@icmse.csic.es
 Protocolo_wetting.pdf Formulario_wetting.pdf
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X-Ray Photoelectron Spectroscopy (XPS/ESCA)
Scientific Responsibles Dr. Juan Pedro Espinós Manzorro, Dr. Juan Pedro Holgado Vázquez
Technical Assistant Dra. Florencia Vattier Lagarrigue, Gdo. Ángel Arias Pérez, Lda. Verónica Rodríguez Bravo
Typically, “photoelectron spectroscopies” are a powerful set of non-destructive analysis techniques, exclusively sensitive to the more superficial few atomic layers (20-30 Å), allowing to obtain valuable information about their chemical, physical and electronic properties.
The technical interest of the resulting information is huge in fields such as catalysis, corrosion, surface treatments,, floating and adhesion phenomena, or segregation processes, among others. The most remarkable characteristic of X-Ray Photoelectron Spectroscopy (XPS/ESCA) is that it allows to discriminate, for a given element, between different oxidation states or chemical surroundings (coordination).
Available Equipment
Photoelectron Spectrometer PHOIBOS 100-DLD, consisting on:
- Analysis Chamber, equipped with a hemispheric multichannel analyser PHOIBOS 100-DLD, a four axis manipulator, a dual X-ray source (achromatic Al Kα, Mg Kα), a UV lamp, and a electron gun, allowing to perform surface analysis by XPS, UPS, ISS and REELS, including angular resolved studies.
- Two prechambers for different treatments, with ultimate vacuum levels of 10-8 and 10-9 mbar respectively, where samples can be subjected to diverse treatments and transferred to the analysis chamber without exposure to the atmosphere. The possible treatments include heating at high temperature (< 800C) under controlled atmosphere, ion sputtering with inert or reactive gases, exposure to plasma, laser treatments, deposition of metals, oxides or simple compounds, exfoliation, etc.
Photoelectron Spectrometer SPECS, consisting on:
- Analysis Chamber, equipped with a hemispheric multichannel analyser PHOIBOS 100, three axis manipulator and dual X-ray source (achromatic Al Kα, Mg Kα).
- Pre-chamber for High Pressure/High Temperature treatments (HPHT Cell).Samples can be subjected to treatments in the presence of gases up to 20 bar and 800ºC (simultaneously). These treatments can be performed either under static or flowing gas conditions. After treatments, samples can be transferred to the analysis chamber without exposure to the atmosphere.
- A Fast entry chamber, equipped with a parking and degassing system, allowing the samples to be evacuated at moderate temperature (T < 150ºC). It is also possible to sputter the samples under an accelerated ion beam (0.5- 5.0 kV) using inert or reactive gases. Incorporation of some other equipment (Visible light illumination, metal evaporators) is also contemplated.
Contact
jpespinos@icmse.csic.es, holgado@icmse.csic.es
954 48 95 31 - 954 48 95 36
 formulario para XPS.docx formulario para XPS.pdf
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