specific molar absorption coefficient (ε = A/bc) #01847OIML 1. The derived SI unit is the square metre per 2 mole (1 m /mol), but the litre per mole per mm (L/(mol × mm)) or litre per mole per cm (L/(mol × cm)) is often used. 2. The specific molar absorption coefficient ε slightly depends on the amount of substance concentration c.