  We present high spatial resolution (0.6 arcsec) near-infrared broad-band JHK
images and Br_gamma 2.1661 micron and H_2 1-0 S(1) 2.122 micron emission line
images of the nuclear regions in the interacting starburst galaxies NGC 520,
NGC 1614 and NGC 7714. The near-infrared emission line and radio morphologies
are in general agreement, although there are differences in details. In NGC
1614, we detect a nuclear double structure in Br_gamma, in agreement with the
radio double structure. We derive average extinctions of A(K) = 0.41 and A(K) =
0.18 toward the nuclear regions of NGC 1614 and NGC 7714, respectively. For NGC
520, the extinction is much higher, A(K) = 1.2 - 1.6. The observed H_2/Br_gamma
ratios indicate that the main excitation mechanism of the molecular gas is
fluorescence by intense UV radiation from clusters of hot young stars, while
shock excitation can be ruled out.
  The starburst regions in all galaxies exhibit small Br_gamma equivalent
widths. Assuming a constant star formation model, even with a lowered upper
mass cutoff of M_u = 30 M_o, results in rather old ages (10 - 40 Myr), in
disagreement with the clumpy near-infrared morphologies. We prefer a model of
an instantaneous burst of star formation with M_u = 100 M_o, occurring 6 - 7
Myr ago, in agreement with previous determinations and with the detection of
W-R features in NGC 1614 and NGC 7714. Finally, we note a possible systematic
difference in the amount of hot molecular gas between starburst and Seyfert
galaxies.
