Laser photoelectron spectroscopy of organometallic anions. [Iron and cobalt carbides]

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7019769

Cheng, C L

This thesis presents the first gas phase spectroscopic study of the FeC, FeC[sub 2], FeC[sub 2]H, and FeC[sub 2]H[sub 2] molecules and the corresponding anions. This series of molecules, as well as the related species CoC, were studied by negative ion laser photoelectron spectroscopy at an instrumental resolution of 4 meV. The apparatus employed in these studies is described, and its intracavity argon ion laser system is discussed in detail. The negative ion photoelectron spectra of FeC and CoC yield ground state vibrational frequencies of 860 and 930 cm[sup [minus]1] for the neutral molecules, respectively, and 860 and 890 cm[sup [minus]1] for the corresponding anions. These high vibrational frequencies indicate that the metal d orbitals are strongly involved in the bonding. Both photoelectron spectra show that the neutral molecule ground states are formed by detachment of an electron from a fairly nonbonding orbital. It is suggested that this orbital is primarily a metal 4s orbital which is polarized away from the carbon center. Molecular orbital diagrams for FeC and CoC are proposed, and their ground states are assigned as [sup 3][delta] and [sup 3][Sigma] states, respectively. The electron affinities of FeC (1.381 [+-] 0.008 eV) and CoC (1.498 [+-] 0.007 eV) are also measured. In addition, more accurate values for the fine structure splittings in the atomic Fe[sup [minus]] and Co[sup [minus]] anions are reported. The negative ion photoelectron spectra of FeC[sub 2], FeC[sub 2]H and FeC[sub 2]H[sub 2] yield electron affinities of 1.977, 1.456 and 1.342 ([+-]0.007) eV, respectively. Neutral molecule vibrational frequencies of 550, 460 and 480 cm[sup [minus]1] are observed for the three systems, respectively, and assigned to the Fe-C stretching modes. Based upon these and other considerations, it is suggested that the three species observed here have a linear FeCC, a linear FeCCH and a C[sub 2v] Fe(HCCH) structure.

• Research Organization: Minnesota Univ., Minneapolis, MN (United States)
• OSTI ID: 7019769
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ANIONS
CARBIDES
CARBON COMPOUNDS
CHARGED PARTICLES
COBALT CARBIDES
COBALT COMPOUNDS
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXCITED STATES
GROUND STATES
IONS
IRON CARBIDES
IRON COMPOUNDS
MOLECULAR STRUCTURE
PHOTOELECTRON SPECTROSCOPY
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
VIBRATIONAL STATES