Pressure-induced H2 opacity in the 5-micron region

The H2 opacity arising from the pure-rotational hexadecapole-induced transitions occurring during H2-H2 and H2-He collisions, and from the hexadecapole-induced and the quadrupole-induced transitions in H2-He collisions, has been calculated. The hexadecapole-induced and quadrupole-induced contributions from H2-H2 collisions are important H2 opacities in the frequency range from 700-3000/cm for temperatures appropriate to the outer planets. It is concluded that this opacity is needed in addition to the opacity from the extrapolation of the 0-0 and 1-0 H2-H2 collisionally-induced bands to interpret the spectrum at 5 microns for the outer planets.