Our laboratory facilities are designed to facilitate a wide variety of state-of-the-art optical spectroscopy experiments, carried out often as a function of high pressure, variable cryogenic tempature, and in some cases also high magnetic field.
In greater detail, the laboratory has severaloperating diamond-anvil cells (DACs) for hydrostatic pressure experiments. Among them are two pressure-tunable DACs for 300K visible spectroscopy in the ranges 0-500kbar and 0-200kbar (the latter uses a unique piezoelectric inch-worm drive), Two cryobaric DACs for visable spectroscopy under tunable pressures and tempatures of 1 atm. to 300kbar and 300-2K, and one DAC for far infrared spectroscopy (and magnetospectroscopy) tunable for pressures of 0-150kbar and tempatures of 300-2K. The latter DAC design is patented by R.J. Chen and B.A Weinstein (U.S. Pat. No. 5,693,345 granted Dec. 2, 1997).
Cryogenic studies are provided by aa Janis Super Varitemp cryostat suitable for experiments at high (or ambient) pressures in the tempature range 300-2K. A displex He-refrigerator with optical windows is also available for more conventional 1 atm. spectroscopy (and other) measurements over 300-10K. An ample, and relatively inexpensive, supply of liquid N coolants is readily provided by the compressor facility at the University of Buffalo.
The spectroscopy experiments that are undertaken in our laboratory include Ramanscattering, photoluminescence (PL), PL-excitation (PLE), transmittion and photo-modulated reflection. These measurements utilize two 5W Ar-ion lasers, a 12WW Krypton-ion laser, a 150W Xenon high pressure lamp (all light sources being CW), a J-Y U-100 one meter double monochromator, and a SPEX 3/4 meter double monochromator. Both monochromatorrs feature either standard photon counting or intensified photodiode array OMA detection. These systems are fully computerized.
In addition to these fixed location apparatuses, there is a mobile spectrometer/laser system employing a 1/2m visible monochromator equipped with an image intensified CCD detector. This system is very fast and sensitive, employing state-of-the-art digital electronics, computer control and analysis softwware. It has been used for visible PL studies and for ruby pressure-calibration on samples in the DAC durring remote far-infrared magnetospectroscopy experiments performed in the laboratory of Prof. B.D. McCombe.
|
|
|
This schematic shows a blow up view of the opposed Bridgman Anvil Configuration for the DAC’s utilized in this lab. The Metal gasket is initially ~300 μm and is indented to ~50-100μm between the diamonds. A circular sample chamber is carefully drilled out and is ~150 μm in diameter. |
|
|
Add Caption here |
Add caption here |
This is a scetch of the cell Rujin Chen and Dr.Weinstein developed and pattented.
