ABSTRACT
In this section, we describe the basic physical properties of natural
DNA: (1) UV/Vis absorption spectra and (2) magnetic properties.
Absorption spectra provide basic information about the electronic
states of DNA: Is there energy gap? If yes, then how much is
the energy gap and how large are the interactions between the
π electrons of bases of intra-and inter-strand? If the DNA is
semiconducting with the energy gap, magnetism based on the π
electrons will not be expected. On the other hand, it has been
reported that natural DNA is expected to show sizable electrical
conductance on the basis of orbital paramagnetism [32, 34]. A lot
of magnetic properties have been reported so far, and the origin and
mechanism of the observed magnetism have been discussed. With
these viewpoints, it is valuable to reexamine precisely the physical
properties of natural DNA.
