  Temperature (T) dependence of 59Co-NMR Knight shifts K of Na0.3CoO2.1.3H2O
has been studied, where samples of randomly oriented powder and aligned
crystals have been used for the applied magnetic fields H // ab plane and H
//c-axis, respectively. For both directions of H, the shift K decreases below
the superconducting transition temperature Tc(H) with decreasing T, indicating
that the superconducting electron pairs are in the singlet state. The upper
critical fields Hc2(T) determined from the K(H)-T curves are found to be
consistent with the values reported by the resistivity measurements for both
directions of H.
