  The excitation functions of capture, complete fusion, and evaporation residue
formation in the $^{16}$O+$^{184}$W and $^{19}$F+$^{181}$Ta reactions leading
to the same $^{200}$Pb compound nucleus has been studied theoretically to
explain the experimental data showing more intense yield of evaporation residue
in the former reaction in comparison with that in the latter reaction. The
observed difference is explained by large capture cross section in the former
and by increase of the quasifission contribution to the yield of fission-like
fragments in the $^{19}$F+$^{181}$Ta reaction at large excitation energies. The
probability of compound nucleus formation in the $^{16}$O+$^{184}$W reaction is
larger but compound nuclei formed in both reactions have similar angular
momentum ranges at the same excitation energy. The observed decrease of
evaporation residue cross section normalized to the fusion cross section in the
$^{19}$F+$^{181}$Ta reaction in comparison with the one in the
$^{16}$O+$^{184}$W reaction at high excitation energies is explained by the
increase of hindrance in the formation of compound nucleus connected with more
quick increase of the quasifission contribution in the $^{19}$F induced
reaction. The spin distributions of the evaporation residue cross sections for
the two reactions are also presented.
