A simple interpretation of the Fe2(-) photoelectron spectrum

The photoelectron spectrum of Fe2(-) can be simply interpreted in terms of electron detachment from the mildly bonding 4s sigma sup * sub u orbital of a (4s sigma sub s)(sup 2) (4s sigma sup * sub u)(sup 2) (3d)(sup 13) anion. This interpretation implies a (4s sigma sub g)(sup 2) (4s sigma sup * sub u)(sup1) (3d)(sup13) configuration for the ground state of Fe2, correlating with one ground state (4s2 3d6) and one excited state (4s1 3d7) Fe atom. A comparison of the bond length and vibrational frequency of Fe2 to values for transition metal dimers containing single 4s-4s bonds is suggestive of 3d-3d bonding in this molecule. The results of preliminary full-valence configuration interaction calculations provide stron support for the proposed Fe2 and Fe2(-) configurations

Mineralogy of volcanic rocks in Gusev Crater, Mars: Reconciling Mössbauer, Alpha Particle X-ray Spectrometer, and Miniature Thermal Emission Spectrometer spectra

Complete sets of mineral abundances for relatively unaltered volcanic or volcaniclastic rocks in Gusev Crater have been determined by modeling Mössbauer subspectral areas as mineral weight percentages, and combining those percentages with the proportions of iron-free minerals not detected by Mössbauer (normative plagioclase, apatite, and chromite, as calculated from Alpha Particle X-Ray Spectrometer (APXS) chemical analyses). Comparisons of synthetic thermal emission spectra calculated for these mineral modes with measured Miniature Thermal Emission Spectrometer (Mini-TES) spectra for the same rock classes show either good agreements or discrepancies that we attribute to sodic plagioclase compositions or unmodeled sulfate, glass, or pigeonite. The normative compositions of olivine, pyroxene, and feldspar calculated from APXS data are consistent with spectroscopic constraints on mineral compositions. Systematic variations between olivine abundances in APXS norms (which sample tens of micrometers depth) and olivine proportions measured by Mössbauer (which sample hundreds of micrometers depth) support the hypothesis that dissolution of olivine by acidic fluids has occurred on weathered rock surfaces

PHOTODETACHMENT ELECTRON SFECTROSCOPY OF FeO−FeO^{-}: DETERMINATION OF THE NEUTRAL MOLECULAR GROUND STATE

Author Institution: Department of Chemistry and Joint Institute of Laboratory Astrophysics, University of ColoradoThe energy spectrum of electrons photodetached from $FeO^{-}$ anions was obtained in a crossed ion-beam/laser-beam apparatus. From this spectrum the electron affinity of FeO could be determined and, additionally, the vibrational frequencies of the ground states of both the anion (760 $cm^{-1})$ and the neutral (970 $cm^{-1})$ were obtained. These FeO studies not only provide an EA(FeO) = 1.497 eV but also show that the state of FeO which has been considered the ground state for thirty years is in fact an excited state lying some 4000 $cm^{-1}$ above the true ground state

A DIRECT DETERMINATION OF THE 1Δ−X3Σ^{1}\Delta-X^{3}\Sigma SEPARATION IN NH BY PHOTOELECTRON SPECTROMETRY OF NH−NH^{-}

$^{1}$A. Gilles, J. Masanet, and C. Vermeil, Chem. Phys. Lett. 25, 346 (1974). $^{2}$C. Zetsch and F. Stahl, Chem. Phys. Lett. 33, 375 (1975).Author Institution: Department of Chemistry and Joint Institute of Laboratory Astrophysics, The University of ColoradoThe energy spectrum of electrons photodetached from $NH^{-}$ anions was obtained in a crossed ion-beam/laser-beam apparatus. This spectrum not only confirms the electron affinity of NH, but also provides a direct measurement of the $A^{1}\Delta -X^{3}\Sigma^{-}$ separation, confirming the postulated assignment of an intercombination transition ($^{1}\Sigma^{+} -^{3}\Sigma^{-}$) recently observed by several $groups.^{1,2}

Deposition and properties of pyrolytic tungsten films

Issued as Technical report no. 1, Project no. A-541Report has title: Deposition and properties of pyrolytic tungsten film

Threshold photodetachment of H-

The electron affinities of atomic hydrogen and deuterium have been determined by tunable-laser threshold-photodetachment spectroscopy: the electron affinities of H (F=0) and D (F=1/2) are 6082.990.15 and 6086.20.6 cm-1, respectively. The value for H is a 20-fold improvement over previous experimental determinations. © 1991 The American Physical Society