  Inelastic proton scattering experiments were performed at the Research Center
for Nuclear Physics, Osaka, with a 295 MeV beam covering laboratory angles
0{\deg}-6{\deg} and excitation energies 6-22 MeV. Cross sections due to E1 and
M1 excitations were extracted with a multipole decomposition analysis and then
converted to reduced transition probabilities with the "virtual photon method"
for E1 and the "unit cross section method" for M1 excitations, respectively.
Including a theory-aided correction for the high excitation energy region not
covered experimentally, the electric dipole polarizability was determined from
the E1 strength distributions. Total photoabsorption cross sections derived
from the E1 and M1 strength distributions show significant differences compared
to those from previous ($\gamma$,xn) experiments in the energy region of the
isocvector giant dipole resonance (IVGDR). The widths of the IVGDR deduced from
the present data with a Lorentz parameterization show an approximately constant
value of about 4.5 MeV in contrast to the large variations between isotopes
observed in previous work. The IVGDR centroid energies are in good
correspondence to expectations from systematics of their mass dependence.
Furthermore, a study of the dependence of the IVGDR energies on bulk matter
properties is presented. The E1 strengths below neutron threshold show fair
agreement with results from ($\gamma$,$\gamma$') experiments on
112,116,120,124Sn in the energy region between 6 and 7 MeV. At higher
excitation energies large differences are observed pointing to a different
nature of the excited states with small ground state branching ratios. The
isovector spin-M1 strengths exhibit a broad distribution between 6 and 12 MeV
in all studied nuclei.
