Surface area of powdered cerous magnesium nitrate

The anomalously small thermal boundary resistance between liquid He3 and powdered cerous magnesium nitrate (CMN) crystals must be due either to an unexpectedly large surface area, to a porous surface layer, or to a new coupling mechanism between the thermal excitations on either side of the interface. Measurement of the surface area of powdered CMN by the BET adsorption method shows that the first two possibilities can be ruled out.