The electronic structure of the NaN2 and NaC2H2 collision pairs is probed b
y optical excitation. Based on polarization experiments, we measure the ali
gnment tensor of the electronic transition dipole moments. We compare the e
xperimental data with the results of a quantum chemical calculation. The di
fferent geometric properties of the electronic wave functions of the two co
llision pairs are directly visible in the experimental data. (C) 2001 Ameri
can Institute of Physics.