Abstract

The J=2 rotons in solid para-H₂ are J = 2 rotational excitations of the molecules traveling through the crystal as a result of the anisotropic intermolecular coupling which is dominated by the electric quadrupole-quadrupole (EQQ) interaction.¹ In the hcp crystal structure three J = 2 rotons at the center of the Brillouin zone (k≈0) are Raman-active and give rise to a triplet of narrow lines at ΔE_para = 6B = 355 cm⁻¹ (B; rotational constant of H₂), split by only 2 cm⁻¹ by the EQQ interaction.

© 1988 Optical Society of America