Rotational spectroscopy
= Rotational spectroscopy
{wiki}
<Rotational spectroscopy> probes transitions between <molecular rotation> <quantum states>. In the simple <linear rigid rotor>, line spacing determines a <moment of inertia>, while an <isotope shift of a linear rotor> tests the mass dependence. More general <molecular geometry> requires several principal <moments of inertia> and more complicated assignments. The combination makes spectra sensitive fingerprints of both composition and shape.