Calorimetry measurements have been used to probe the melting of aluminum cluster cations with 63 to 83 atoms. Heat capacities were determined as a function of temperature (from 150 to 1050 K) for size-selected cluster ions using an approach based on multicollision-induced dissociation. The experimental method is described in detail and the assumptions are critically evaluated. Most of the aluminum clusters in the size range examined here show a distinct peak in their heat capacities that is attributed to a melting transition (the peak is due to the latent heat). The melting temperatures are below the bulk melting point and show enormous fluctuations as a function of cluster size. Some clusters (for example, n = 64, 68, and 69) do not show peaks in their heat capacities. This behavior is probably due to the clusters having a disordered solid-like phase, so that melting occurs without a latent heat. © 2007 American Society for Mass Spectrometry.
Neal, C. M., Starace, A. K., & Jarrold, M. F. (2007). Ion Calorimetry: Using Mass Spectrometry to Measure Melting Points. Journal of the American Society for Mass Spectrometry, 18(1), 74–81. https://doi.org/10.1016/j.jasms.2006.08.019