Determination of the 14N quadrupole tensor of phenazine in its lowest excited triplet state by ODNQR

The first complete determination of the 14N nuclear quadrupole tensor in the photoexcited triplet state of an organic molecule was made feasible by an alternative to ODENDOR. Instead of using a simultaneous desaturation method (cw-ODENDOR), a procedure involving sequential population transfer between specific electron–nuclear spin levels was adopted. This new method is demonstrated for phenazine-d8 in a Shpolskii matrix and yields ‖e2qQ/h‖= (4.36±0.02) MHz; η=+0.21±0.03.