  We present an analysis of two experimental approaches to controlling the
directionality of molecular rotation with ultrashort laser pulses. The two
methods are based on the molecular interaction with either a pair of pulses (a
"double kick" scheme) or a longer pulse sequence (a "chiral pulse train"
scheme). In both cases, rotational control is achieved by varying the
polarization of and the time delay between the consecutive laser pulses. Using
the technique of polarization sensitive resonance-enhanced multi-photon
ionization, we show that both methods produce significant rotational
directionality. We demonstrate that increasing the number of excitation pulses
supplements the ability to control the sense of molecular rotation with quantum
state selectivity, i.e. predominant excitation of a single rotational state. We
also demonstrate the ability of both techniques to generate counter-rotation of
molecular nuclear spin isomers (here, ortho- and para-nitrogen) and molecular
isotopologues (here, 14N_2 and 15N_2).
