Fourier transform infra-red spectroscopy (FT-IR) is a prime tool for the in situ analysis of chemical composition, charge densities, and precise amounts of substances under study. An absorbance peak in IR region might be exactly attributed to the chemical bond responsible for the extinction of light at a given wavelength. Equinox-55 is the elaborate FT-IR setup from BrukerOptics which is working in the attenuated total reflection mode (ATR). Multiple reflections of a light beam at the crystal interface allow accumulation of signal so that even a single monolayer adsorbed might be characterized. This setup is equipped with a thermo stabilized flowthrough liquid cell from Harrick Scientific. This ensures that polymer multilayer structure growth might be constantly monitored and the compositional response to the change of environment is recorded.
Fluorescent Correlaton Spectroscopy (FCS) allows us to measure the concentration, the diffusion coefficient, and the dynamics of different processes of fluorescent species in solution and on surfaces. The advantages of FCS are its extreme sensitivity even at nanomolar concentration and wide range of times scales. This home-built setup is designed to work with the most popular fluorescent dyes which are excited in a green wavelength range. Dye molecules must be covalently attached to the molecules under study. The measurement takes just a few minutes and might be done with a single droplet of sample solution. Single molecule sensitivity and the simplicity of the correlated data analysis make FCS one of the most useful tools for studying polymer dynamics.
Phase-modulated ellipsometry is an advanced technique designed to measure the thickness and the refraction coefficient of thin films deposited on various flat surfaces. In contrast with other ellipsometric methods, the high-frequency phase-modulation of the incident laser beam allows measurement of fast changes of thickness in 1ms. For most dry samples the precision of measurement is less than 1 Ångström. This home-built setup is equipped with a cylindrical liquid cell which is used to measure film thickness in situ and vary the properties of the solvent. Depending on the nature of the film and its thickness, it is possibile to reconstruct the refraction coefficient and the thickness simultaneously. Extensive data analysis allows measurement of multilayered films as well.
Surface-enhanced Raman spectroscopy (SERS) is a spectroscopic technique which provides unique vibrational signatures for analytes. We explore SERS for robust chemical and biological sensing using the frontier of hollow- and solid-core photonic crystal fibers (PCFs) with nanoscale-functionalized hollow core and cladding air holes, respectively.
High pressure liquid chromatography (HPLC) is the method of separation and purification of chemical compounds dissolved in various mixtures of aqueous and organic solvents. The main principle of the separation is the different affinity of chemicals under study to the stationary phase which results in different times every component takes to come through the separation column. The solution is pumped through the column at high pressure and after separation every single compound is detected by UV-absorption, refractive index change, light scattering, or fluorescent detection. The HPLC setup from Waters is a flexible instrument comprising several units, each of them is easily interchangeable and upgradeable. Gel permeation chromatography (GPC) columns are mostly used for polymer fractionation and purification.
The Zetasizer Nano Z measures the size of particles in a fluid down to less than a nanometre by observing the thermal movement, or Brownian motion, of the particle. Submicron particle sizes are measured by observing the scattering of laser light from these particles, determining the diffusion speed and deriving the size from this, using the Stokes-Einstein relationship. It also measures the zeta potential of dispersed particles and macromolecules in solution over a size range 3 nm to 10 microns. The set-up is operating with a 4 mW, 633 nm He-Ne laser and the scattered light is detected at an angle of 17°. The temperature range can be tuned between 2 °C and 90 °C. The zeta potential is measured using a combination of measurement techniques: electrophoresis and Laser Doppler Velocimetry.
The homemade robot is used for routine fabrication of multilayers onto planar substrates.
In the wet-chemistry lab, we perform synthesis of polymers and nanoparticles, as well as surface modification.