Facilities

General Description. The facilities currently occupied by the Dluhy research group within the Department of Chemistry at the University of Georgia consist of faculty and student office space, a wet chemistry laboratory, and two instrumentation laboratories. The wet laboratory occupies ~600 ft² and is used for chemical and biochemical sample preparation. One instrument laboratory consists of ~1100 ft² and currently holds Langmuir-Blodgett surface chemistry equipment, infrared spectrometers, and associated optical accessories. Another instrument laboratory consists of ~600 ft² and currently houses the dispersive Raman spectrometer laboratory in addition to the epifluorescence microscope. An additional 500 ft² is available for student and faculty offices.

Infrared Spectroscopy Instrumentation. There are at present three Fourier transform infrared spectrometers in our laboratories. All these instruments are currently configured for the mid-infrared spectral range with high temperature (2000 K) SiC ceramic or Nichrom wire sources, Ge-on-KBr beamsplitters, and either room-temperature TGS or liquid N₂-cooled HgCdTe detectors.

One of these IR spectrometers is a Perkin-Elmer (Norwalk, CT) Spectrum 2000. It has an user-designed auxiliary sample compartment attached to the external beam port of the spectrometer where experiments may be permanently mounted. The Perkin-Elmer 2000 has been modified to do monolayer reflection experiments in addition to being used for other types of experiments.

A second IR spectrometer is a Bruker Equinox 55 (Bruker Optics, Billerica, MA).  This instrument is optically interfaced to a variable angle external reflection accessory (Bruker model XA511-A) for monolayer reflection experiments. The external reflection accessory is equipped with a custom-designed Langmuir trough (Riegler & Kirstein, Berlin, Germany) containing a micro-balance Wilhelmy sensor for surface pressure readings.  This accessory is able to automatically change angles of incidence and polarization states under spectrometer control.  In addition, this particular IR spectrometer contains a multiplexing capability, enabling a polarization modulator to be easily interfaced for PM-IRRAS experiments of thin films. We have set up a PM-IRRAS experiment on this instrument using a ZnSe photoelastic modulator (PEM-90, Hinds Instruments, Hillsboro, OR) operating at its resonance frequency fm of 50 kHz.  Signal processing of the PM-IRRAS detector output is accomplished dual-channel electronics with lock-in detection.  At the output of the electronic filters, both I_ac and I_dc signals were combined using a multiplexer and sent to the 16-bit ADC of the Bruker IR spectrometer.

The third IR spectrometer is a Digilab (Randolph, MA) FTS-7000 instrument.  This instrument has step-scanning capabilities combined with digital signal processing.  It is used for kinetic experiments as well as ATR and polarization-modulation measurements of thin films on metallic substrates.  We have set up a PM-IRRAS experiment for supported films on solid substrates using this instrument in conjunction with a ZnSe photoelastic modulator (PEM-90, Hinds Instruments, Hillsboro, OR) operating at its resonance frequency f_m of 37 kHz.  Signal processing of the PM-IRRAS detector output is accomplished using the digital signal processing capabilities of the FTS-7000 instrument.

Dry air purge of these IR spectrometers is obtained using Balston Model 60 compressed air dryers, which provide a H₂O-vapor-free air supply for the spectrometers. Cooling of the high temperature black-body IR sources is performed using recirculating refrigerators. The IR spectrometers are mounted on 4' x 8' vibration isolation optical benches obtained from Modern Optics (Thousand Oaks, CA) and Newport Optical (Fountain Valley, CA).

Raman Spectroscopy Instrumentation.  A custom-designed, dispersive Raman spectrometer is available in this laboratory. It is based on a Spex 0.5 meter scanning monochromator (ISA, Inc., Edison, NJ) coupled to a liquid-N₂ cooled CCD detector (SiTE, 2000 x 800 pixels). Raman scattered radiation is generated using a 5 watt Ar⁺-ion laser (Coherent Lasers, Model 305, Santa Clara, CA) that pumps a solid-state Ti:Sapphire laser (Coherent Ring Laser, Model 890). This laser combination generates visible radiation (e.g. 488 or 514.5 nm) from the Ar⁺-ion laser as well as tunable near-IR radiation in the wavelength range 785-900 nm from the Ti:Sapphire laser. Laser plasma lines are filtered out prior to sample excitation using either a small grating monochromator or wavelength-specific band-pass filters. Rayleigh line scattering is eliminated using holographic notch filters (Kaiser Optical, Ann Arbor, MI). A home-built, f/4 fiber optic interface is attached to the axial entrance port of this monochromator.

A fiber-optic-interfaced confocal Raman microscope is also available. This unit is based on an Olympus BX-60 research light microscope with an integrated, single-mode (f ~ 7 mm), fiber-optic input/output module (HoloLab Series 5000, Kaiser Optical, Ann Arbor, MI) that delivers the excitation laser light to the microscope and collects the Raman scattered radiation. Apochromatic microscope objectives of 50X (NA 0.75) and 100X (NA 0.95) are available. This microscope is configured for a laser excitation wavelength of 785 nm and therefore has a theoretical spatial resolution of approximately 1.0 mm (lateral) and up to 0.8 mm confocal (axial) using the 100X objective. The Raman scattered light is delivered to a f/1.8 holographic imaging spectrograph (HoloSpec f/1.8I, Kaiser Optics, Ann Arbor, MI) using fiber optics. The detector on this spectrograph is a Princeton Instruments liquid-N₂ cooled CCD detector (1024EHRB, 1024 x 256 pixels) that is back-illuminated and is specifically optimized for high QE in the near-IR spectral region (~35% at 1000 nm).  A dedicated 785 nm near-IR diode laser (Invictus, Kaiser Optical) is used to provide the excitation wavelength for this instrument.

A third spectrometer is also available in the lab for Raman and other optical spectroscopy experiments.  It is composed of a Spex 1877 Triplemate equipped with 600 groove/mm gratings in its filter stage, a choice of either 600, 1200 or 1800 groove/mm gratings in the spectrograph stage, and is equipped with both photomultiplier (Burle C31304) or CCD (Photometrics, Series 200, 512 x 512 pixels) detection.  Visible wavelength excitation for this instrument is provided by a Coherent Model 90 Ar⁺-ion laser; in addition, tunable excitation wavelengths over a wide range may be generated by use of a Coherent Model 599 standing wave dye laser in conjunction with the Ar⁺-ion laser.

Langmuir-Blodgett Film Balances. Much of the research performed in this laboratory involves the spectroscopy of ultrathin organic and bio-organic films. We are well-equipped for this type of research by having several monolayer film balances for the deposition, manipulation, and analysis of ultrathin films. One of these Langmuir-Blodgett troughs is based on a constant-perimeter ribbon design from Joyce-Loebl, Ltd. (Gateshead, UK). We have a second Langmuir-Blodgett dipping trough based on a dual-barrier design from Nima Technology (Coventry, UK).  Both of these systems are computer-controlled, alternate-layer film balances used for depositing pre-formed monolayers from a liquid surface onto solid substrates with full programmability of dipping sequences, speeds, and surface tension. In addition, because of their alternate-layer design, multilayer films of two (or more) individual monolayers may be sequentially constructed. Several additional Nima Langmuir-type film balance instruments are available for the manipulation and analysis of monolayer films on liquid surfaces. These instruments have been i) interfaced to an IR spectrometer for the in-situ vibrational analysis of monolayer films on liquid substrates, ii) used on a epifluorescence microscope for the morphological characterization of interfacial monolayers, and iii) used for fluorescence photobleaching experiments.

High purity, 18.3 Mega-ohm H₂O for surface chemistry and laboratory applications is obtained from either a Barnstead (Dubuque, IA) Nanopure or Millipore (Billerica, MA) Milli-Q combined reverse osmosis/deionization system.

IR Sampling Accessories. In addition to the normal transmission optics found in a laboratory dedicated to infrared spectroscopy, a wide variety of infrared sampling accessories are available. Aqueous solutions may be studied by attenuated total reflectance using either a micro or macro Circle Cell (Spectra-Tech, Stamford, CT) or a variable reflection liquid cell (Harrick Scientific, Ossining, NY). Monolayer films on reflective metal substrates may be studied using an external reflection grazing angle accessory (Harrick Scientific). A 4X beam condenser (Spectra-Tech) is available for ATR studies of thin films on parallelogram ATR crystals; a micro-transmission flow cell is available for use with the 4X beam condenser.  A horizontal ATR sampling accessory is available (CIC Photonics., Albuquerque, NM) for flow cell and liquid ATR experiments. An addition horizontal ATR sampling accessory (Harrick Scientific) is available with a temperature-controlled stage.  A diffuse reflectance accessory is available, as is a 10 cm pathlength gas cell. Even longer pathlengths for gaseous samples are available using a variable 20 m gas cell.  Vibrational linear or circular dichroism may be generated using either a 37 or 50 KHz ZnSe photoelastic modulator (Hinds International, Portland, OR) in conjunction with electronic filters and digital lock-in amplifiers (Stanford Research Systems, Inc.)

Epifluorescence Microscope.  We have recently installed a custom epifluorescence microscope for morphological characterization of monomolecular films at the air-water interface.  The microscope itself is built around a commercial epifluoresence microscope body (AxioTech Vario, Carl Zeiss Jena, Germany).  Real-time detection is accomplished by using a low light level camera (SIT camera C2400-08, Hamamatsu, Japan). Images are directly stored into computer memory via an on line image processor (Argus 20, Hamamatsu, Japan).  The digital resolution of the images is better the 3 pixels per micrometer, resulting in an optical resolution of approximately one micrometer.  The film balance is placed on an X-Y stage (Aerotech) for adjusting the observed area and to compensate any small film drift. The entire setup is isolated from building vibrations by an active vibration isolation table (Halcyon, Switzerland).

Computer Hardware/Software. Each of the infrared and Raman spectrometers are controlled by PC’s operating Windows 98/NT/2000/XP with the spectrometer manufacturers software. Data from these computers is transferred via a local intra-net to other computer workstations for data analysis, computation, or word processing. Networked printers available for generating hard copy output from the IBM microcomputers include Hewlett-Packard LaserJet 4 and H-P 4500 color laserjet printers (both with PostScript capability).

A number of commercial software packages are available on the IBM PC for the graphical display and manipulation of data. Grams AI (Galactic Industries, Nasuha, NH) is used for display and plotting of IR spectral data, while Sigma-Plot (Jandel Scientific, Corte Madera, CA) is used to plot scientific and technical graphs for publication. Other standard commerical software packages are used, e.g. MS Word for word processing and MS Excel for spreadsheet-type applications. Fortran, Pascal, C, Basic, and Visual Basic compilers are available for computer software development in the laboratory. 

In addition to the commercial software described above, a number of computer programs have been developed in-house specifically for the post-processing of infrared spectra or the calculation of the reflectance properties of materials. In particular, programs written in our lab for the Matlab environment are used for the calculation of 2D correlation analysis algorithms.

Departmental Research Facilities. Chemistry Department shared use equipment at UGA includes Bruker 250 MHz, 300 MHz, 400 MHz and 500 MHz NMR spectrometers within the Chemistry Department Instrumentation Facility; access is also available to 600 and 800 MHz NMR spectrometers at the Complex Carbohydrate Research Center on campus.  Small molecule crystal structures may be determined using an Enraf-Nonius CAD-4 single-crystal X-ray diffractometer. Mass spectra may be obtained on three separate instruments. A Finnigan 4000 GC/MS is used to obtain mass spectra of small molecules; either capillary or direct probe insertion is possible. High molecular weight samples may be analyzed using a Sciex API-1 quadrupole mass spectrometer with electrospray ionization source interfaced to an ABI microbore HPLC system. A Bruker time-of-flight MS is used for laser desorption analysis of high molecular weight compounds (1,000-300,000 Da) and is also able to perform tandem mass spectrometry measurements on molecules in the 1,000-10,000 Da range.

Departmental computing resources are provided by an ethernet local area network to a variety of additional processors. Network services are provided through a campus-wide broadband data network. The Chemistry Department is connected to this network so that mainframe computers are available through high-speed network links. The University supports a supercomputer facility which presently manages two systems, which supports many ab initio, semi-empirical, and classical computational chemistry codes, including MM2, MM3, and GAUSSIAN. The Biological Sequence/Structure Computation Facility is available for the computation, display, and manipulation, of macromolecular structures.  This facility supports many of the powerful molecular mechanics and molecular dynamics packages such as AMBER, CHARMm, and SYBL.

Other research support services include a glassblowing shop with two full-time glassblowers in the Chemistry Building and a University-wide Instrument and Electronics Shop, which is maintained in its own 40,000 ft² building. In addition, the Molecular Genetics Instrumentation Facility is available as a University-wide resource for the synthesis and analysis of polypeptides and polyoligonucleotides. This facility is built around instrumentation from Applied Biosystems, Inc., and includes a DNA synthesizer, solid phase peptide synthesizer, gas phase and pulsed liquid phase sequencers, and amino acid analyzer.