Anisotropy of the Adiabatic Relaxation Time of Adsorbed He Monolayer.

This paper investigates the anisotropy of the adiabatic relaxation time $T_{2}^{\prime}$ ( T( ω), ω→∞, where ω is the Larmor frequency) of adsorbed monolayer solid He. We calculate $T_{2}^{\prime}$ based on the phenomenological Heisenberg Hamiltonian with the nearest-neighbor and the next nearest-neighbor exchange interactions. Furthermore, the four particle exchange in the triangular plane is also incorporated. To calculate $T_{2}^{\prime}$, it is necessary to compute the second and the fourth moments of the resonance line $M_{2}^{0}$ and $M_{4}^{0}$. To obtain them, we can use the formulas published in previous studies. From the results, we can observe no significant difference between the nearest-neighbor Heisenberg model and the four particle spin interaction models. A comparison of the present results and the experimental data is briefly discussed. [ABSTRACT FROM AUTHOR]