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Mass spectrometric investigations of fullerenes. I. Vapour pressure over the C 60 /C 70 binary system
Author(s) -
Popović Arkadij,
Dražič Goran,
Marsel Jože
Publication year - 1994
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1290081216
Subject(s) - chemistry , fullerene , sublimation (psychology) , knudsen number , vapor pressure , analytical chemistry (journal) , enthalpy , thermodynamics , chromatography , organic chemistry , psychology , physics , psychotherapist
The absolute vapour pressures over pure C 60 , C 70 , fullerite and over the binary C 60 /C 70 system are calculated from ion intensities vs. temperature up to 800 K using the Knudsen effusion mass spectrometric method. The vapour pressures (Pa) of C 60 and C 70 are given as a function of temperature (K) by the equations:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} \log p = - (8276.4 \pm 120)/T + 10.49 \pm 0.14,{\rm for }C_{60} \\ \log p = - (9106.4 \pm 130)/T + 10.70 \pm 0.15,{\rm for C}_{{\rm 70}} \\ \end{array} $$\end{document} Corresponding Second Law enthalpy and entropy changes for sublimation are:\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} \Delta H_{{\rm subl}}^0 = 158 \pm 3{\rm kJ}/{\rm mol }\Delta {\rm S}_{{\rm subl}}^{\rm 0} = 105 \pm 1.5{\rm kJ}/{\rm mol}, for C_{60} \\ \Delta H_{{\rm subl}}^0 = 174 \pm 3{\rm kJ}/{\rm mol }\Delta {\rm S}_{{\rm subl}}^{\rm 0} = 109 \pm 1.5{\rm kJ}/{\rm mol, for C}_{{\rm 70}} \\ \end{array} $$\end{document} Results are discussed in terms of sample purity and pretreatment and correlated with data obtained by other authors. Fullerenes containing residual organic solvents (fullerite) partly decompose upon thermal treatment to amorphous carbon.