Instrumentation

Equipment

Major equipment in Schanze research lab in the Department of Chemistry at the University of Texas at San Antonio include:



Femtosecond Transient Absorption Spectroscopy

IMG_1741Femtosecond-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.

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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.

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IMG_3176Unisense 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.


IMG_3175AM1.5 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.

 


IMG_3173Incident 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.


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Screen Printer

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.

 

 


IMG_3158Layer-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.

 

 


img_1734.jpgSpin Coater

 

 

 

 

 

 

 

 


IMG_1879Pico/Nano TCSPC

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.



 


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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.


 

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Fluorometer

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.



img_1746.jpgNIR-PTI Fluorometer 

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).


IMG_1754IMG_1713

 

 

 

 

 

UV-Vis Spectrophotometer

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).


IMG_1717Gel 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.

 


IMG_1728Dynamic 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.



img_1727.jpgMicroplate Reader

 

 

 

 

 



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Gas-Chromatography 

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.

 

 

 


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Microwave Reactor

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.

 


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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.

 



IMG_1704Argon Box

Argon box is helpful for storing and handling chemicals that are sensitive to air and moisture.

 

 

 

 

 



IMG_1709Dry 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.

 

 



IMG_1720Furnace

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).

 

 



IMG_1724Freeze dryer

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.