AC calorimetry technique. Applications to liquid helium films and liquid crystals

We review and detail the use of the AC calorimetry technique as we have applied it to the study of phase transitions. Theory of operation, materials and electronic equipment considerations are discussed in detail. Examples of its use in heat capacity measurements of two-dimensional helium films at sub-Kelvin temperatures and bulk liquid crystal materials at or above room temperature are presented. The high resolution and usefulness of the AC technique are evident from these studies. (Author). 32 refs, 6 figs