Knowledge Bank

Vibrational ladders of the spherical-top molecules $SiF1,SF1$, and $UF1$ will be discussed. Special attention will be paid to the $\nu 3$ ladders, which can be easily pumped up to the vibrational ``quasicontinuum'' and on to dissociation. The differing vibrational state densities of these molecules result in differing behavior in multiphoton absorption and laser-induced photodissociation. Vibrational states have been calculated, with anharmonicity included, for these molecules for vibrational energies of up to $15,000cm-1$ and for state densities of up to $108levels/cm-1$; comparison will be made with the results of the approximation method of Whitten and $Rabinovitch.1$ The effect of anharmonicity in increasing the state densities, and implications for photochemistry and thermodynamics, will be discussed.