Major equipment in Schanze research lab in the Department of Chemistry at the University of Texas at San Antonio include:
Femtosecond Transient Absorption Spectroscopy
Femtosecond-picosecond transient absorption spectroscopy is used to study ultrafast dynamics of excited states produced in photoactive molecular, polymer and materials systems. The system in our lab consists of a Coherent Astrella amplified Ti:sapphire laser that produces 100 fs duration, 800 nm pulses at 1 kHz repetition rate. The Ti:sapphire output is used to pump a OPA which gives wavelength tunable 100 fs pulses. The system is combined with an Ultrafast Systems Helios pump probe spectrometer that allows measurement of transient absorption spectra on timescales from 100 fs – 8 ns in the UV-visible and near-infrared regions.
Figure above shows transient absorption spectra (left) and dynamics of a series of platinum acetylide conjugated oligomers.
Nanosecond Transient Absorption Spectroscopy
The pump utilizes a pulsed Nd: YAG laser (Quanta-Ray INDI-40-10) with a repetition rate of 10 Hz. Its 355 nm light can be used as a direct pump or an OPO generates wavelengths ranging from 410-710 nm. The setup contains a focusing lens, a Pellin-Broca prism and a train of mirrors to direct the beam into a λ/2 plate / Wollaston prism combination which serves as a variable attenuator. The probe is a pulsed 450 W Xenon lamp to obtain a high flux of photons for sensitivity at the nano to microsecond timescale. For measuring transients over longer timescales, a halogen lamp is utilized with much less intensity. High-speed shutters are used to time the pump and probe beams. Transients are observed at a single wavelength and a digital storage oscilloscope records the information. We are able to measure the lifetime of a state from 200 – 1200 nm.
Unisense Microsensor Multimeter
The Unisense Microsensor Multimeter is a 4-channel laboratory amplifier that is able to measure multiple parameters at once. Two channels for amperometric sensors (O2, NO, H2, H2S, N2O, NOx–), one for potentiometric sensors (pH and Redox) and one channel for a temperature sensor give complete flexibility for experiments.
AM1.5 Solar Simulator
The Solar Simulator is intended for the researcher who needs to closely simulate the sun’s spectra, but doesn’t need the precise uniformity and high level of spectral match of a Class AAA Solar Simulator. This Solar Simulator uses a 150 W ozone free xenon lamp, and produces a 1.3-inch (33 mm) diameter collimated beam. Optional air mass and bandpass filters can be added to re-shape the spectral output.
Incident photon-to-current efficiency (IPCE)
The IPCE indicates the ratio of the number of photons incident on a solar cell to the number of generated charge carriers. It is used to understand the conversion efficiency as a function of the wavelength of light impingent on the cell; and from which, the composition and topography can be modified to optimize conversion over the broadest possible range of wavelengths.
Screen printing is a simple manufacturing process based on screen-printing is crucial for a successful commercialization of dye-sensitized solar cells. It is an industrial fabrication method to disperse nanocrystalline homogeneously.
Layer-by-Layer Robot (LbL)
Layer-by-Layer assembly is a convenient and generally applicable method for the fabrication of nanofibrillar films by exploiting the dynamic nature of polymeric complexes. This process involves the sequential deposition of two or more materials that physically bond together.
Time-Correlated Single Photon Counting (TCSPC) is used to determine the fluorescence lifetime of a chromophore in the ps and ns timescale. In TCSPC, one measures the time between sample excitation by a pulsed laser and the arrival of the emitted photon at the detector. The time delay measurement is repeated for many times to account for the statistical nature of the fluorophores emission.
Fluorescence Correlation Spectroscopy
Fluorescence Correlation Spectroscopy (FCS) is a correlation analysis of temporal fluctuations of the fluorescence intensity. The method records temporal changes in the fluorescence emission intensity caused by single fluorophores passing the detection volume. The fluorescence intensity changes can be quantified in their strength and duration by temporally auto-correlating the recorded intensity signal that gives information about the average number of fluorescent particles in the detection volume and their average diffusion time through the volume.
Fluorometer is used to obtain the steady state fluorescence and phosphorescence of a sample. The fluorescence intensity and wavelength of a sample can provide an indirect evidence of the sample’s environment, solvent-solute interactions, inter- and intramolecular interactions, etc. Fluorometer can be used for various quantitative analysis like measuring the emission quantum yield of a sample, binding constants, Stern-Volmer plot, etc.
The NIR-PTI fluorometer with InGaAs photodiode near-IR detector is helpful in recording the emission spectra of samples that emit in the near-IR region (ex: singlet oxygen emits around 1250 – 1300 nm).
The compact UV-2600 is a universal, research-grade spectrophotometer that can be used in a wide range of fields, and easily expanded to suit the measurement objective. Equipped with a single monochromator, providing low noise performance across a wide wavelength range. Enables near-infrared measurements (up to 1400 nm).
Gel Permeation Chromatograph (GPC)
GPC is a technique for the separation of macromolecules like natural and synthetic polymers. It is the method of choice for the characterization of polymer molecular weight and molecular weight distribution.
Dynamic Light Scattering (DLS)
DLS is used for the characterization of proteins, antibodies, nanoparticles, macromolecular assemblies and other molecules/particles of small sizes. It uses backscattering detection for the highest sensitivity and accuracy optimized for molecules and particles less than a few tens of nanometers. Detection at 90° is used for larger particles.
Gas chromatography is a commonly used chromatographic technique for separating and analyzing compounds that can be vaporized without decomposition. It is useful in determining the number of compounds and their percentage ratio in a mixture.
Microwave Reactor is designed to enhance the ability to perform chemical reactions under controlled conditions on a laboratory scale. Microwave chemistry is based on the efficient heating of materials by “microwave dielectric heating” effects. This phenomenon is dependent on the ability of a specific material (solvent or reagent) to absorb microwave energy and convert it into heat.
Teledyne Flash Column Chromatography
Teledyne flash column chromatography is a very useful instrumentation facility available to purify and isolate organic compounds (through both normal & reverse phase systems) quickly when compared to the traditional gravity column.
Argon box is helpful for storing and handling chemicals that are sensitive to air and moisture.
Dry Solvent Dispenser
Dry solvent dispenser system purifies the commercial solvents in a easy way and dispenses it pure and dry quickly. These systems operate by pushing the solvents through a series of drying columns that reduces the moisture levels down to the ppm range.
The tube furnace is used for the preparation of metal oxide thin films on a substrate such as glass. This furnace is programmable allowing you to set the heating time and temperature (up to 1100 degrees celcius).
The freeze dryer is used for the dehydration of liquid or slurry products, which have previously frozen, under the vacuum. The freeze drying process allows the frozen water in the material to sublime directly from the solid phase to the gas phase.