General-purpose facilities and instructional equipment are described in instructional facilities. Some instructional equipment is of sufficient sophistication to be used for research. Here only systems used exclusively for research are described.
Optical studies of semiconductors using photoreflectance techniques make use of a system comprising a monochromator, white light source, laser, chopper, and photodetector and lock-in amplifier. The system is computer controlled. A number of additional light and laser sources have been acquired for this work. Most samples for this work have been prepared by other groups elsewhere using MBE techniques. Facilities for sample preparation here include a number of turbo- or diffusion-pumped vacuum systems with evaporation and sputtering abilities. Optics experiments of light scattering from particles suspended in fluids make use of a commercial particle size counter (Spectrex) and a locally built apparatus equipped with several lasers of various wavelengths. A CCD camera and PC-based imaging system is also available. Efforts to interpret remote sensing satellite data and relate it to scattering properties are done with a Sun workstation running IDL.
Rooms 345 and 395 MWAH contain equipment necessary for low-level mercury analyses of various environmental matrices. The Raman Spectroscopy Laboratory is located in room 343 MWAH.
Analytical Equipment used for Mercury Analyses
- atomic absorption spectrometer - model 5000, LDC Analytical
- headspace sampler - model 7694, Hewlett Packard
- gas chromatograph (GC) - model 5890, Hewlett Packard
- atomic emission detector - model 5921A, Hewlett Packard
- GC controller - model 382, Hewlett Packard
- GC injector - model 7673, Hewlett Packard
- analytical balances - models 100 \& 200, Mettler
Raman Spectroscopy Equipment
- argon ion laser - model CR-18, Coherent
- single frequency dye laser - model CR-599-04, Coherent
- mode locker - model 467SE, Coherent
- cavity dumper and driver - model 7200, Coherent
- double monochrometer -model 1403, SPEX
For AFM imaging, detection of the frequency shift is accomplished with a dual phase lock-in amplifier (SR830) monitoring the phase relation between drive voltage and current; on resonance the tuning fork behaves like a pure resistance and any reactive component to the current signals a shift in the resonant frequency and is used as a error signal in a home-built feedback controller. For frequency-distance studies an commercial digital phase-locked loop/FM demodulator (Nanosurf easyPLL) provides a more direct tracking of frequency shifts. Coarse positioning of AFM samples near probe tips is accomplished with a commercial piezoelectric inchworm (Burleigh Microinchworm and 6000ULN computer-interfaced controller). Scanning and fine distance control is all done with home-built single piezoelectric tube x-y-z scanners of conventional design. Data acquisition is done with LabVIEW running on Windows PCs. Two machines are available, each equipped with data acquisition cards (NI-6036E or CIO DAS 1600 from Measurement Computing) and GPIB for programmable instruments (SR830, SR335 and SR345 generators, EGG5209 lock-in). MWAH 16 also houses the low temperature facility, with a locally designed cryostat with a 4He pot and detachable dilution refrigerator stage, associated pumps and gas handling system, nitrogen-free dewar, a helium storage dewar, and an old Veeco MS-90 leak detector.
The Swenson College of Science and Engineering maintains an online catalog of instrumentation available for research purposes.
Computational resources within the department are described elsewhere. Campus-wide resources, primarily in the form of network services and computing services on the central Sun Sparc system, are available. Much of the computational physics research involves use of supercomputer facilities available in Minneapolis; time is granted by the Minnesota Supercomputing Institute.
Physics faculty associated with the Large Lakes Observatory have additional equipment at their disposal. A laboratory for work on high-energy particle astrophysics is under development.