(1) An elastic fluid is a fluid
whose properties can be approximated as those of a harmonic oscillation and
which possesses sufficient cohesiveness to maintain its structure and to
transmit disturbances.
(2) The +1, 0, -1 symbol refer to a
limiting isotropic (spherical) system which has no directional properties and
the spins line up precisely in an external magnetic field. In this limit the spin angular momentum
is a good quantum number so the state can be characterized as T-1,
T0 T+1. . This is an accurate representation of a
radical pair or weakly coupled biradical.
It is not appropriate for a molecule, since molecules do not have
cylindrical symmetry (exception: C60!)
For
molecules when the system has roughly cylindrical symmetry for the orbitals
involved in the triplet, the cylindrical axis is label z and the other two as
x,y. Group theory and MOs are used
to decide how to label the axis in complex cases. For the n,pi* state the z axis is the C-O bond assuming rough
cylindrical symmetry.