Silyl group internal rotation in [ital S][sub 1] phenylsilane and phenylsilane cation: Experiments and [ital ab] [ital initio] calculations

Journal Article · Wed Sep 15 04:00:00 EDT 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.466079· OSTI ID:6024094

Lu, K; Weisshaar, J C ^[1]

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1. Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

Resonant two-photon ionization (R2PI) and pulsed field ionization (PFI) were used to measure [ital S][sub 1]--[ital S][sub 0] and cation--[ital S][sub 1] spectra of internally cold phenylsilane. We measure the adiabatic ionization potentials IP(phenylsilane)=73 680[plus minus]5 cm[sup [minus]1], IP(phenylsilane [center dot]Ar)=73 517[plus minus]5 cm[sup [minus]1] and IP(phenylsilane [center dot]Ar[sub 2])=73 359[plus minus]5 cm[sup [minus]1]. We assign many low lying torsion--vibration levels of the [ital S][sub 1] ([ital [tilde A]] [sup 1][ital A][sub 1]) state and of [ital [tilde X]] [sup 2][ital B][sub 1] of phenylsilane[sup +]. In both states, the pure torsional transitions are well fit by a simple sixfold hindered rotor Hamiltonian. The results for the rotor inertial constant [ital B] and internal rotation potential barrier [ital V][sub 6] are, in [ital S][sub 1], [ital B]=2.7[plus minus]0.2 cm[sup [minus]1] and [ital V][sub 6]=[minus]44[plus minus]4 cm[sup [minus]1]; in the cation, [ital B]=2.7[plus minus]0.2 cm[sup [minus]1] and [ital V][sub 6]=+19[plus minus]3 cm[sup [minus]1]. The sign of [ital V][sub 6] and the conformation of minimum energy are inferred from spectral intensities of bands terminating on the 3[ital a][sup [double prime]][sub 1] and 3[ital a][sup [double prime]][sub 2] torsional levels. In [ital S][sub 1] the staggered conformation is most stable, while in the cation ground state the eclipsed conformation is most stable. For all sixfold potentials whose absolute phase is known experimentally, the most stable conformer is staggered in the neutral states ([ital S][sub 0] and [ital S][sub 1] [ital p]-fluorotoluene, [ital S][sub 1] toluene, [ital S][sub 1] [ital p]-fluorotoluene) and eclipsed in the cationic states (ground state toluene[sup +] and phenylsilane[sup +]).

• DOE Contract Number: FG02-92ER14306
• OSTI ID: 6024094
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 99:6; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664200* -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
664400 -- Experimentally Derived Information on Atomic & Molecular Properties-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION
ADIABATIC PROCESSES
ARGON COMPLEXES
ATOMS
CATIONS
CHARGED PARTICLES
COMPLEXES
ENERGY SPECTRA
HAMILTONIANS
HYDRIDES
HYDROGEN COMPOUNDS
IONIZATION
IONIZATION POTENTIAL
IONS
MATHEMATICAL OPERATORS
MOLECULES
MULTI-PHOTON PROCESSES
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHOTOIONIZATION
PULSES
QUANTUM OPERATORS
RESONANCE ABSORPTION
SILANES
SILICON COMPOUNDS
SORPTION
SPECTRA