Physics Department of Moravian College, Bethlehem, PA Moravian College
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[ Research Information ]

Mössbauer Spectroscopy:

"Mössbauer spectroscopy is a spectroscopic technique based on the resonant emission and absorption of gamma rays in solids. This resonant emission and absorption was first observed by Rudolf Mössbauer during his graduate studies in 1957, and is called the Mössbauer effect in his honor." [ quote from wikipedia.org ]

Dave Hart, '00Seen to the left is Dave Hart ('00), working on his senior Honors project on Mössbauer spectroscopy of amorphous materials.  The source (10 millicurie of Co57), drive unit, and detector are located on the concrete slab to the left of Dave and to the right of the rack, which contains the multi-channel analyzer, power supplies, and timing/flyback module.  Mossbauer spectroscopy allows one to examine the nuclear environment in a very precise way, using the Doppler effect to sweep through a range of energy levels.

Since 2005 we have been interested in examining substituted cobalt-ferrites, and have produced a number of publications in the Journal of Applied Physics. Our experimentation has primarily examined the effects that substituting various elements (such as Ga, Cr, Mn, Ge, Co, and Al) into the cobalt-ferrite structure have had on the structure of such materials - specifically the substitution of these elements for Fe in the tetrahedral and octahedral sites of the crystal structure. The materials have been produced for us by researchers at Iowa State University and Cardiff University in Wales.

Cr Results [2004]:

Raw Data
Raw Data
Data fitted with WMOSS
Data fitted with WMOSS
Hyperfine Field Data
Hyperfine Field Data
Distrubution Width Data
Distribution Width Data
Isomer Shift Data
Isomer Shift Data

Mn Results [2005]:

Raw Data
Raw Data
Data fitted with WMOSS
Data fitted with WMOSS
Hyperfine Field Data
Hyperfine Field Data
Distrubution Width Data
Distribution Width Data
Isomer Shift Data
Isomer Shift Data

Ga Results [2007]:

Raw Data
Raw Data
Data fitted with WMOSS
Data fitted with WMOSS
Hyperfine Field Data
Hyperfine Field Data
Distrubution Width Data
Distribution Width Data
Isomer Shift Data
Isomer Shift Data

Comparison of Hyperfine Field Data for Cr, Mn, and Ga:

Comparison

Magneto-Optical Kerr Effect [MOKE]:

"The light that is reflected from a magnetized surface can change in both polarization and reflectivity. The effect is identical to the Faraday effect except that the magneto-optical Kerr effect is a measurement of the reflected light, while the Faraday effect is a measurement of the transmitted light. Both effects result from the off-diagonal components of the dielectric tensor ε." [ quote from wikipedia.org ]

Chad Weiler, '00 & Dave Hart, '00
Shown here are Chad Weiler ('00) on the left, and Dave Hart ('00) on the right, sitting behind the optics table which holds Chad's senior Honors project on the magneto-optical Kerr effect of ferromagnetic thin films (only a few atomic layers thick).  The laser on the lower left of the picture (a 30 mW He-Ne laser) is sent through a chopper and reflected off of the sample which is between the poles of a magnet.  The reflected laser light is partially polarized due to the alignment of the magnetic moments of the material.  By examining the reflected light as the magnetic field is varied, a hysteresis curve is produced which illustrates the magnetic alignment of the atoms in the material.

Images of the Experiments:

Raw Data
Experimental Setup
Data fitted with WMOSS
Experimental Setup
Hyperfine Field Data
Experimental Setup
Distrubution Width Data
Experimental Setup
Isomer Shift Data
Preliminary Data

Other Research:

Raw Data
Raman Spectroscopy
Data fitted with WMOSS
Open Cavity Laser Experiments
Hyperfine Field Data
Open Cavity Laser Experiments
Distrubution Width Data
Hydraulic Jump Phenomena*
Isomer Shift Data
Laser Sputtering**

*Hydraulic Jump Phenomena:

Commonly referred to as the "kitchen sink" experiment, this project involves examining the patterns formed when a viscous fluid impinges onto a horizontal plate.   The hydraulic jump is an oft-studied phenomena of fluid dynamics in which the fluid depth of a radially spreading flow increases suddenly with a corresponding decrease in flow velocity, analogous to a shock wave.  We are interested in characterizing the standing wave patterns that form within the hydraulic jump radius.  Shown above is our experimental set-up, which includes a fluid flow system and an imaging system.

**Laser Sputtering:

If a small HeNe laser is underpowered, the laser sputters in an irregular manner.   We are interested in characterizing this sputtering phenomena using techniques from nonlinear dynamics (chaos theory).  The experimental set-up is shown above and includes a small 1 mW HeNe laser and Pasco light intensity probe.

 
     
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