Photoionization mass spectrometric study of Si sub 2 H sub 6

Journal Article · Thu Aug 15 04:00:00 EDT 1991 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.460946· OSTI ID:5614774

Ruscic, B; Berkowitz, J ^[1]

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1. Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (USA)

The adiabatic I.P. of Si{sub 2}H{sub 6} obtained by a photoionization mass spectrometric study at two temperatures is 9.74{plus minus}0.02 eV. The first fragment, Si{sub 2}H{sup +}{sub 4}, initially appears with a shallow slope at {le}10.04{plus minus}0.02 eV, and with a much steeper slope at {le}10.81{plus minus}0.02 eV. It is argued that the initial onset corresponds to formation of H{sub 2}SiSiH{sup +}{sub 2}, while the steeper onset is attributed to formation of H{sub 3}SiSiH{sup +}. The second fragment, Si{sub 2}H{sub 5}, has an appearance potential of {le}11.59{plus minus}0.02 eV (11.41{plus minus}0.03 is a probable value). Successive decomposition leads to Si{sub 2}H{sup +}{sub 2} (from Si{sub 2}H{sup +}{sub 4} ) and Si{sub 2}H{sup +}{sub 3} (from Si{sub 2}H{sup +}{sub 5} ). The photoion yield curve for Si{sub 2}H{sup +}{sub 3} also displays shallow and steep onsets. Upper limits for the appearance potentials can be readily extracted, but the true thermochemical onsets are less well defined. Heats of formation (or upper limits) are presented for each of these species. For Si{sub 2}H{sup +}{sub 6}, Si{sub 2}H{sup +}{sub 5}, and Si{sub 2}H{sup +}{sub 4}, the experimental values are in good agreement with recent {ital ab} {ital initio} calculations. For the daughter species, the experimental values exceed the calculated ones, as expected.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5614774
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 95:4; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ENTHALPY
FORMATION HEAT
HYDRIDES
HYDROGEN COMPOUNDS
IONIZATION
IONIZATION POTENTIAL
MASS SPECTROSCOPY
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHOTOIONIZATION
PHYSICAL PROPERTIES
REACTION HEAT
SILANES
SILICON COMPOUNDS
SPECTROSCOPY
THERMODYNAMIC PROPERTIES