Temperature gradients in ultrafast thin-film nanocalorimetry

Abstract

Temperature gradients can significantly affect the accuracy of ultrafast thin-film nanocalorimetry. In this regard, the problem of dynamic heat transfer for thin-film sensors of different geometry is solved analytically. Temperature distributions are analyzed in the direction perpendicular to the membrane of the calorimetric sensor, as well as in the lateral direction for the unloaded sensor and the sensor loaded with the sample. Different sensor designs are considered, including commercially available ultrafast sensor XEN-39472. Temperature gradients at different scanning rates up to 108 K/s were investigated. It was found that the temperature gradients in the membrane plane are significant even in quasi-static mode at scanning rates below 106 K/s and even in unloaded sensor. Possibility of improving the calorimetric sensors is studied. Based on the calculations of the analytical model, recommendations for modification of the sensor design are obtained.