= Solution
Using the stipulated integer <isotope> masses gives
$$
\mu=\frac{12\times32}{44}u=8.72727u,\qquad
I=\mu(1.53\times10^{-10}\ \mathrm m)^2
=3.39243\times10^{-46}\ \mathrm{kg\,m^2}.
$$
The <rotational constant> in <wavenumber> units is
$$
\boxed{\widetilde B=\frac{h}{8\pi^2cI}=0.8252\ \mathrm{cm^{-1}}.}
$$
Here $c$ must be expressed in $\mathrm{cm\,s^{-1}}$ when $I$ is in SI units. Equivalently calculate $B=h/(8\pi^2I)$ in $\mathrm{Hz}$ first, then divide by $c$ in $\mathrm{cm\,s^{-1}}$.
Back to article page
