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Beer Law Constants and Vapor Pressures of HgI2 over HgI2(s,l)Optical absorption spectra of the vapor phase over HgI2(s,l) were measured at sample temperatures between 349 and 610 K for wavelengths between 200 and 600 nm. The spectra show the samples sublimed congruently into HGI2 without any observed Hg or I2 absorption spectra. The Beer's Law constants for 15 wavelengths between 200 and 440 nm were derived. From these constants the vapor pressure of HgI2, P, was found to be a function of temperature for the liquid and the solid beta-phases: ln P(atm) = -7700/T(K) + 12.462 (liquid phase) and ln P(atm) = -10150/T(K) + 17.026 (beta-phase). The expressions match the enthalpies of vaporization and sublimation of 15.30 and 20.17 kcal/mole respectively, for the liquid and the beta-phase HgI2. The difference in the enthalpies gives an enthalpy of fusion of 4.87 kcal/mole, and the intersection of the two expressions gives a melting point of 537 K.
Document ID
Document Type
Reprint (Version printed in journal)
Su, Ching-Hua (NASA Marshall Space Flight Center Huntsville, AL United States)
Zhu, Shen (Universities Space Research Association Huntsville, AL United States)
Ramachandran, N. (Universities Space Research Association Huntsville, AL United States)
Burger, A. (Fisk Univ. Nashville, TN United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Journal of Crystal Growth
Volume: 235
ISSN: 0022-0248
Subject Category
Solid-State Physics
Distribution Limits