Introduction
Several techniques now allow scientists and engineers to
see atoms. Among these are X-ray diffraction, nuclear magnetic resonance
(NMR) and magnetic resonance imaging (MRI), and various forms of microscopy.
X-Ray Diffraction
The first detector systems for X-ray diffraction used photographic
film. To simulate this experiment, Optical Transform Kits and separate optical
transform slides are available from the
Institute for Chemical Education (ICE), .
An X-ray photograph of
DeoxyriboNucleic Acid (DNA) taken by, Rosalind Franklin , led to the elucidation of the 3-D structure of DNA
by Watson and Crick.
The March, 1999 issue of the Journal of Chemical Education
contains our insert "Liver and Onions: DNA Extraction from Animal and Plant
Tissue."
DNA Optical Transform Kit
The DNA Optical Transform Kit , available from the Institute for Chemical
Education (ICE), will assist instructors in teaching students about DNA
and how its structure was solved. The kit is comprised of a booklet and
the DNA optical transform slide, which is based on an article in the March,
1999 issue of the Journal of Chemical Education by Amand Lucas, et. al.
The booklet contains:
-
a section describing the basic principles of X-ray
diffraction that were used to solve the structure of B-DNA.
-
a section relating X-ray diffraction to optical transforms.
-
a section describing the masks on the DNA optical transform
slide and how they relate to the X-ray diffraction structural analysis
of DNA.
-
an activity that describes how students can use the
DNA optical transform slide.
-
a copy of the insert, "Liver and Onions: DNA Extraction
from Animal and Plant Tissues," from the March, 1999 issue of the Journal
of Chemical Education.
-
a copy of the article "Revealing the Backbone Structure
of B-DNA from Laser Optical Simulations of X-ray Diffraction Diagrams"
by A. A. Lucas, Ph. Lambin, R. Mairesse, and M. Mathot, which also appears
in the March, 1999 issue of the Journal of Chemical Education.
-
a section containing a list of publications and web
site addresses that describe DNA and the effort to determine its structure.
-
an Appendix containing transparency masters and a suppliers
list.
In recent years the power of X-ray diffraction has been greatly
enhanced through the use of an area detector. The Charge Coupled Device detector is also used in digital cameras, modern
spectrometers, and liquid chromatographs.
Solid State Model Kit
The
Solid State Model Kit, available from the
Institute for Chemical Education (ICE) , is a very useful tool for illustrating
the arrangement of atoms in the solid state. Layer diagrams for large number
of different crystal systems are described in the manual. The kit contains
four sizes of colored plastic spheres which represent the atoms in the lattice.
These spheres are placed on metal rods mounted in holes in a plastic base.
The kit contains two bases and numerous cardboard templates. This very flexible
system allows the construction of a large number of different crystal systems.
Nuclear Magnetic Resonance Spectroscopy (NMR)
and Magnetic Resonance Imaging (MRI)
Microscopy
Other important tools for scientists and engineers are various
types of microscopy. These include
Scanning Probe Microscopy (SPM) , Magnetic Force Microscopy (MFM), Atomic Force Microscopy (AFM) and
Lateral Force Microscopy (LFM).
