Аннотация:The heat capacity of a high-purity sample of acridinium dietetracyanoquinodimethanide [acridinium ${(\mathrm{TCNQ})}_{2}$ or Ad${(\mathrm{TCNQ})}_{2}$] was measured at temperatures from 0.5-10 K in fields of 0, 10, 20, and 40 kOe. The results are shown to correspond very well, within the experimental accuracy, to a superposition of a ${T}^{3}$ lattice contribution and a random-exchange antiferromagnetic Heisenberg-chain magnetic contribution. The Bulaevski\ifmmode \breve{\imath}\else \u{\i}\fi{} theory parameters derived from these heat-capacity measurements without the use of any exogenous data are found to be $\ensuremath{\alpha}=0.75\ifmmode\pm\else\textpm\fi{}0.01$ and $A=(1.69\ifmmode\pm\else\textpm\fi{}0.04)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ ${\mathrm{K}}^{\ensuremath{-}0.25}$. The Debye temperature is found to be 68.3\ifmmode\pm\else\textpm\fi{}0.2 K.
