It is no coincidence that the isotope that has been studied the most in the Mossbauer field is Fe57.  This iron isotope is of extreme biological importance.  Approximately seventy-five percent of all experimental papers on Mossbauer Spectroscopy deal with Fe57.  By pure luck, however,  Fe57 happens to have almost ideal characteristics that make it  the most easily observable Mossbauer nuclide.  Our research revolves around Fe57 because even after all the papers and extensive study of this isotope, unknowns remain.  Also, the applications of Mossbauer research of Fe57 are endless.  The prime example is the better understanding of iron porphyrins.

Porphyrins, are vital chemical compounds produced by all living organisms.  Porphyrins are  necessary for cell respiration.  A porphyrin molecule is planar and looks like a circular ring made of  four rings linked together, a fundamental skeleton is shown below. Atoms of various metals positioned in the center of the large ring distinguish different porphyrins. A much more familiar example is hemoglobin's prosthetic group, heme, which is an iron porphyrin.  There is also Chlorophyll, the substance that gives green plants their color, which is a magnesium porphyrin.  For in depth information on porphyrins see links on the Reference Page.

The Mossbauer experimental setup can be very simple and affordable, or very expensive and complex.  The main three parameters that the Mossbauer spectroscopist can vary to study samples are: temperature, magnetic field, and the Doppler shift.  Obviously, the most simple experimental setup consists of a zero-magnetic-field room-temperature spectrometer, and the most complex spectrometers are designed to run at cryogenic temperatures and with very high magnetic fields.

In Knox we currently work with  two spectrometers with these specifications:

1. A spectrometer consisting of a top loading loading cryogenic dewar that can be used to study samples at liquid helium or nitrogen temperature.  This dewar is part of super conductive magnet that delivers up to 9 Tesla of applied field.  This low temperature, high applied field spectrometer runs very smoothly and is in perfect operational order.
2. A spectrometer consisting of a top-loading closed cycle cryostat from Cryo-Industries (Model REF-399-D22).  As advertised by the manufacturer, this cryostat's advantage is that it does not use any cryogenic helium or nitrogen; and, the cryostat is "Plug and Play," you supply  220 V at  60 Hz and the refrigerator unit can take you anywhere from room temperature down to ~15 K.  The samples are loaded from the top and can be changed in seconds without shutting off the refrigerator. This cryostat also features independent temperature control of sample mount and refrigerator cold finger.  This closed cycle cryostat is a real joyride, indeed.  HOWEVER, as with any refrigerator, the motor on this unit produces vibrations that need to be very carefully isolated.  Part of my independent study work has been to engineer the stand for the cryostat and the rest of the spectrometer apparatus: the proportional counter and the velocity transducer.

The CCC spectrometer:  The Closed Cycle Cryostat Spectrometer

The CCC is shown in the picture above.  Part of my previous research project on Mossbauer spectroscopy during this past summer, was the construction of the stand for the spectrometer apparatus.  "The stand" had to meet the most important Mossbauer requirement: "sufficient" vibration isolation.  Also, lead shielding around the source was needed.  Here follows a pictorial description of how "the stand" came to be:
 
 

The plan was to attach the CCC by its bottom part  to a very heavy "cinder-block and sand" base.  This would damp the vibration from the motor into the ground and also provide a very stiff support.