A new type of cation-compensated Fe + (S = z) center designated [Fe04/M]&, with M =Li and H, has been found to exist in synthetic iron-doped a-quartz, through an X-band electron paramagnetic resonance study. The spin-Hamiltonian parameters at temperature approximately 20 K were determined for both centers, allowing for anisotropy of the g factor as well as gand 0-matrix noncoaxiality, and including high-spin terms of the form S . While the Li hyperfine matrix was not obtainable, the EPR measurements did yield the proton hyperfine matrix for M =H. For M = Li, in contrast to the C2 symmetry of the previously studied [Fe04/Li], center P shows C, symmetry at low temperatures (20 K), but approaches C2 symmetry at higher temperatures (approximatelỹ 160 K). The hydrogenic center, designated as [Fe04/H]0&, shows C& symmetry up to room temperature. The analysis of the spin-Hamiltonian parameter matrices for both the n (the previously studied form) and the P form of the cation-compensated Fe + centers indicates that the (interstitial) M ion is located, respectively, at opposite sides of the slightly distorted [Si(Fe)04] "tetrahedron. "

Infrared and Raman spectra have been measured for spiropentane-H8. Raman spectra for the liquid have enabled the b1 species ring twist to be assigned. Previous assignments of this mode were based on calorimetric data and on the assignment of a band in the infrared spectrum to a combination band involving the ring twist mode. Infrared spectra of low temperature crystalline films have provided sufficient information that, when taken with the Raman data and gas phase infrared spectra, we have assignments for all of the fundamental modes.

No abstract

No abstract