Auger Electron Spectroscopy Study of the Chemisorption of Iodine on Zirconium

Abstract

Auger electron spectroscopy was used to observe the relative coverage of iodine on the surface of a zirconium crystal exposed to a flux of iodine gas molecules. The zirconium was heated to temperatures of 1000–1300 K, and the iodine pressures corresponded to 10−4–10−6 Pa (10−9–10−11 atm). Iodine was found to chemisorb on the surface; the isotherms corresponded to the Temkin model. Isoteres derived from these isotherms showed a logarithmic dependence of pressure on reciprocal temperature. The slopes of the isoteres indicated an enthalpy of formation of the surface layer of about 60 kcal/mole. The thermodynamics of formation of an iodine adspecies on a zirconium surface were compared with the thermodynamics of formation of zirconium monoiodide, the lowest solid iodide of zirconium.

Nanoscale Ruthenium-Containing Deposits from Ru(CO)4I2 via Simultaneous Focused Electron Beam-Induced Deposition and Etching in Ultrahigh Vacuum: Mask Repair in Extreme Ultraviolet Lithography and Beyond

“…After deposition with 1.56 C/cm 2 , signals at 200, 231, and 273 eV indicative of the Ru MNN transitions are visible, along with the carbidic C signal at 249 eV (the C KLL peak at 265 eV is hidden under the Ru peaks) . The characteristic (main) I MNN Auger peaks for I are observed at 509 and 519 eV . While the latter are barely distinguishable for 1.56 C/cm 2 (red spectrum in Figure c), they are clearly visible at higher doses.…”

“…45 The characteristic (main) IMNN Auger peaks for iodine are observed at 509 and 519 eV. 47 While the latter are barely distinguishable for 1.56 C/cm 2 (red spectrum in Figure 2c), they are clearly visible at higher doses. The increase of a broad and small peak at approximately 420 eV can also be attributed 45 Auger spectra are often measured (using lock-in techniques), plotted and analyzed in the differential form, that is dI/dE vs energy (I: intensity, E: kinetic energy), which makes the separation of overlapping peaks very difficult.…”

“…The 47 The characteristic (main) I MNN Auger peaks for I are observed at 509 and 519 eV. 49 While the latter are barely distinguishable for 1.56 C/cm 2 (red spectrum in Figure 2c), they are clearly visible at higher doses. The increase of a broad and small peak at approximately 420 eV can also be attributed to I signals because three additional I transitions have previously been reported for the kinetic energy peak positions at 380, 437, and 446 eV.…”

Surface characterization

“…Both LEED and UPS were employed in the investigation of the interaction of fractional monolayers of Te on Zn[0001] (1). Zirconium has been studied for chemisorption of iodine using AES (324) and CO, NO, N2, 02, and D2 using A(j>, TD, and AES (184). The oxidation of cadmium [0001] was examined using LEED and AES (288).…”

Estimated Thermodynamic Properties of the Solid Zirconium Iodides

“…--(G o --H%gs)/T were found for solid ZrI, ZrI2, or ZrI2. They were estimated by the method used by the authors of the JANAF Table (8) for ZrC12 and ZrC18 as follows.…”