Can the frequency-dependent specific heat be measured by thermal effusion methods?

TL;DR

This paper investigates whether thermal effusion methods can measure frequency-dependent specific heat and finds that spherical geometries also involve the longitudinal specific heat rather than the isobaric specific heat.

Contribution

It demonstrates that heat effusion in spherical symmetry measures the longitudinal specific heat, not the isobaric specific heat, clarifying the interpretation of thermal effusion measurements.

Findings

Spherical heat effusion involves the longitudinal specific heat.

Plane-plate methods also measure the longitudinal specific heat.

Implications for frequency-dependent specific heat measurements.

Abstract

It has recently been shown that plane-plate heat effusion methods devised for wide-frequency specific-heat spectroscopy do not give the isobaric specific heat, but rather the so-called longitudinal specific heat. Here it is shown that heat effusion in a spherical symmetric geometry also involves the longitudinal specific heat.