CRYSTAL FIELD SPLITTING OF THE $ {\Delta}$ J = 6 PURE ROTATIONAL $W_{O}(0)$ TRANSITION OF SOLID HYDROGEN: THEORY AND OBSERVATION

$^{1}$M.Okumura,M.-C.Chan, and T.Oka, Phys.Rev.Lett. 62,32(1989) $^{2}$R.E.Miller and J.C.Decius, J,Chem,Phys, 59, 4871(1973) $^{3}$Van Kranendonk, Phsica 25,1180(1959);J.Van Kranendonk,Can,J.Phys. 38,240(1960). $^{4}$S.Luryi and J.Van Kranendonk, Can,J.Phys. 57,933(1973) $^{5}$T.K.Balasubramanian, R.D'Souza, R.D'Cunha, and K.N. Rao, Can.J.Phys. 6779(1989)""Author Institution: Department of Chemistry and Department of Astronomy and Astrophysics, the University of ChicagoThe pure rotational W ($\Delta J=6)$ transition of solid parahydrogen has been studied using high resolution difference frequency spectroscopy. In addition to the sharp feature reported in the previous $work,^{1}$ two new peaks were observed. This triplet structure agrees with the prediction from group $theory.^{2}$ These features were interpreted as the M levels in the $J = 6$ state split by crystal field interactions, based on the fact that the relative intensities of these components vary depending on the polarization of infrared source. Unlike the $J = 2$ roton, whose M splitting was interpreted by the roton hopping model of Van $Kranedonk,^{3}$ the $J = 6$ roton is relatively localized based on an order of magnitude estimation of the hopping Hamiltonian. The observed splitting of $\sim 0 .01$ $cm^{-1}$ was therefore explained by the anisotropic induction and dispersion interactions of a localized J = 6 roton with the surrounding $J = 0$ molecules using the same treatment as the case of the crystal field effect of a localized J = 1 molecule in an otherwise $J = 0$ $solid.^{4}$ The M value of each component was assigned according to $intensity^{5}$ and energy calculations. The assignments, crystal field splitting, and spectral linewidth will be discussed following this idea