ELECTRONIC SPECTRUM OF THE $SiCl_{3}$ RADICAL
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Date
1992
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Ohio State University
Abstract
Between 330 and 400 nm the 2+1 REMPI spectrum of $SiCl_{3}$ exhibits two overlapping vibrational progressions composed of $>30$ members and one vibrational progression composed of 5 members. These band systems, labeled $\tilde{F}$, $\tilde{G}$, and $\tilde{H}$, are tentatively assigned to three distinct Rydberg states that reside between 50100 and $59600 cm^{-1}$. The vibrational progressions have an average spacing of $\omega_{2}=262 cm^{-1}$ and are assigned to the $\nu_{2}$ umbrella modes of the Rydberg states. Electronic origins are not observed. Ab initio calculations on $SiCl_{3}$ and $SiCl_{3}^{+}$ yield geometries and harmonic vibrational frequencies consistent with the spectroscopic assignments and provide the adiabatic ionization potential, $IP_{a}$ = 7.93 $\pm$ 0.05 eV. In combination with a recent experimental value for $\Delta H_f(SiCl_{3}^{+})$, this leads to $\Delta H_f(SiCl_{3}) = -353 \pm 12$ kJ/mol.
Description
Author Institution: Chemical Kinetics and Thermodynamics Division, National Institute of Standards and Technology