Fig. 2.

Experimental echo decays, measured using the CPMG pulse sequence and associated with hydrogen molecules, for three angles ${\theta }_{\mathrm{S}}$ between the normal N to the film plane and the applied magnetic field, ${\overrightarrow{H}}_0$ : i) ${\theta }_{\mathrm{S}}=40°$ blue curve; ii) ${\theta }_{\mathrm{S}}=65°$ green curve; iii) ${\theta }_{\mathrm{S}}=90°$ red curve. Inset is the log of the echo decay.