  Dynamical properties, such as dynamical spin and charge structure factors and
single-particle spectral functions, are studied for the one-dimensional
supersymmetric t-J model with inverse-square interaction. Exact diagonalization
and the recursion method are used for finite systems up to 16 sites. A simple
rule is proposed to understand the supermultiplet structure in the excitation
spectrum. Numerical calculations show that the dynamical spin structure factor
is independent of the electron density in the region where only two spinons
contribute. In the electron removal spectrum from half-filling, close
correspondence is found between the dominant contribution from three-spinon
plus one-holon states in the t-J model and the two-spinon excitations in the
Haldane-Shastry model. Comparison is made with dynamics of the nearest-neighbor
supersymmetric t-J model.
