Browsing by Author "Farhat, Shahla Khan"

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    Color center laser kinetic spectroscopy: Evidence for quasilinearity of HCCN
    (1994) Farhat, Shahla Khan; Curl, Robert F., Jr.
    The C-H stretching fundamental of the free radical HCCN has been investigated under high resolution using infrared kinetic spectroscopy. This transient molecule was produced by the flash photolysis of dibromoacetonitrile (Br$\sb2$HCCN) at 193 nm and its transient infrared absorption spectrum probed using a color center laser. Spectra of the molecule were collected between 3182 and 3274 cm$\sp{-1}$. The rotational analysis of the $\nu\sb1$ fundamental places its origin at 3246.657 cm$\sp{-1}$. Four hot bands associated with the bending vibrations have been observed; the vibrational and rotational assignment of three of these bands $\nu\sb1 + \nu\sb5 - \nu\sb5$, $\nu\sb1 + \nu\sb4 - \nu\sb4$, and $\nu\sb1 + 2\nu\sb5\sp{\pm 2} - 2\nu\sb5\sp{\pm 2}$ is definite. The $\nu\sb5$ energy was obtained by measuring the intensity of a line of the $\nu\sb1 + \nu\sb5 - \nu\sb5$ band relative to one of the fundamental and calculating the energy assuming a room temperature Boltzmann distribution. A comparison of this energy with that of quasilinear fulminic acid, HCNO, and with theoretical calculations suggests a similar floppy HCX bending potential.