A RAMAN STUDY OF THE ISOTOPIC DEPENDENCE OF THE PHASE TRANSITION IN NAPHTHALENE-TETRACYANOBENZENE

Abstract

In this laboratory, the solid state phase transition temperature of the charge transfer complex naphthalene-tetracyanobenzene (N-TCNB) was recently found to be $70\pm 1^{\circ}, K$ by magnetic resonance $methods^{1}$ Since this value differs from that reported recently using Raman scattering $data,^{2}$ we decided to re-examine the Raman spectrum to try to find the source of the discrepancy. In addition, in an attempt to further understand the mechanism of the phase transition, we also carried out a similar study of the corresponding complex with perdeuterated naphthalene ($Nd_{8}$-TCNB). While the low frequency spectra of the two complexes are qualitatively similar, the observed frequencies for $Nd_{8}$-TCNB agree with those given in the previous $report^{2}$ We found the phase transition to occur at $69 \pm 2^{\circ};K$ for $Nh_{8}$-TCNB and $61 \pm 2^{\circ};K$ for $Nd_{8}$-TCNB. It thus appears that the previous work was carried out with the perdeuterated naphthalene complex. Details of this work and, of further experiments in progress will be given. Also, possible explanations for the effect of naphthalene deuteration on the phase transition temperature will be discussed.