Research

Dr.Alem Teklu
Office: J.C. Long 220
Office Hours: OFFICE HOURS GO HERE      
Homepage
phone: 843.953.7187
email: teklua@cofc.edu

Atomic Force Microscopy

       
The Flex-AFM made by Nanosurf is a very reliable tool for topographical and metrological imaging of samples in both air and liquid. It has also been used for advanced mechanical, electrical, or magnetic characterization.

Resonant Ultrasound Spectroscopy

   
The Modulus II device measures the elastic properties of materials by using the principle of Resonant Ultrasound Spectroscopy (RUS). The technique employed here works because the mechanical resonances of a solid are dependent upon geometry, density, crystalline symmetry, and elastic constants. The apparatus is a dedicated, rather than a general, analytical tool and thus it is designed uniquely and specifically for this particular task. There is only one model available form Dynamic Resonance Systems (DRS). No other apparatus is available for taking the needed measurements and doing the requisite analysis. The key to obtaining accurate moduli from a RUS measurement is to ensure that the measured resonances are those of a free body. This requires very weak transducer contact, and therefore signals are small. To extract such signals, the DRS International system uses state-of-the-art low-noise components in a digitally synthesized/filtered heterodyne swept-sine signal analyzer. As with all such systems, phase and amplitude information appears at an intermediate frequency or IF (977 Hz for the DRS system). The DRS system employs a fully digital IF processing scheme with user-selectable filtering via the number of IF cycles processed for each data point. The DRS system also allows the user to adjust a delay between points to allow the sample "ringing" to settle, and provides user-adjustable drive amplitude and number of data points taken. To implement all these features, the hardware is controlled by a WINDOWS software package.

Fourier Transform Infrared Spectroscopy

       
Varian 7000 FTIR Spectrometer System with MTEC Model 300 Photoacoustic Spectrometer System (NIR and MIR Regions) (1) 125 W High intensity water cooled ceramic IR source (range 9,600-50 cm-1), PERMATRAC 2™ A 60 degree Michelson air bearing interferometer, a design found only on the highest quality research grade spectrometers. The PERMATRAC 2™ interferometer is dynamically aligned by patented Piezo-stack technologies. The PERMATRAC 2™ interferometer in combination with the 125 W water-cooled source deliver an unprecedented 160 mW of IR power to the sample position. (2) 0.10 cm-1 resolution at 4,000 cm-1. (3) Step scan capability - provides scan speeds from 800 Hz to 1 step every 250 seconds. In the amplitude modulation mode the FTS 7000 can be used with source (e.g. chopper) or sample modulation with an external lock-in amplifier. Phase modulation is also available, at frequencies up to 1000 Hz. Phase modulation measurements are performed in conjunction with DSP. Step scan also includes operation in time resolved spectroscopy mode "TRS", with 5 microsecond time resolution and event trigger. (4) Digital Signal Processing (DSP3) for modulation experiments. Provides three modes of operation; DSP1, DSP2 and DSP3. DSP1 demodulates the sample response in a step-scan photoacoustic measurement with phase modulation. It is a replacement for the Varian demodulator board or a lock-in amplifier for PAS applications, providing the sample in-phase and in-quadrature response to the phase modulation of the spectrometer.

Scanning Electron Microscope

       
We have a Hitachi TM-1000 scanning electron microscope for faculty and student research. Specifications of the SEM include: Magnification: 20~10,000× (digital zoom: 2, 4×) Accelerating voltage: 15kV Observation mode: Standard mode/charge-up reduction mode Specimen traverse: X:15 mm, Y:18 mm Maximum sample size: 70mm in diameter Maximum sample thickness: 20mm Electron gun: Pre-centered cartridge filament.

updated: 24 August 2016