Knowledge Bank

Steady state and time-resolved IR spectroscopy have been used to study the vibrational band positions, vibrational energy relaxation (VER) rates, and reorientation times of the antisymmetric C$\equiv$N stretching band of dicyanamide (N(CN)$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$) anion near 2100 $\backslash wn$ in several bulk solvents. The transient signals indicate a complicated relaxation mechanism, consistent with there being a Fermi resonance enhanced combination band in the region. The solvent-induced spectral blue shifts and VER rates both increase for solvents with stronger solute-solvent interactions. The gas-phase vibrational frequency is estimated by extrapolating to zero solvent shift by scaling the solvent shift to those previously observed for azide (N$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$). N(CN)$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$ exhibits a strong correlation between vibrational frequency and VER rate, so that, as with N$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$$\mathrm{<mrow\; data-mjx-texclass="ORD">-</mrow>}$, an estimate of the relative VER rate can be obtained from the static spectra.