MATRIX DEUTERATION EFFECTS AND SPIN-LATTICE RELAXATION IN THE LOWEST TRIPLET OF THE PALLADIUM(II) COMPLEX PD(2-THPY)(2)

Pd(2-thpy)(2) isolated in protonated or deuterated frozen n-octane (Sh pol'skii matrices) exhibits highly resolved triplet emission and excit ation spectra. One observes interesting differences for the two matric es: (i) The protonated matrix shows only one dominant guest site while the deuterated matrix exhibits two dominant sites. (ii) Low-energy sa tellites corresponding to lattice modes are distinctly shifted to lowe r energy due to deuteration of the matrix. (iii) 1.3 K the triplet sub levels emit independently with lifetimes being nearly equal for both m atrices. However, for 1.3 < T < 5 K one observes obvious differences i n the decay behavior. This is explained by substantially smaller rates of spin-lattice relaxation in the deuterated host. Different mechanis ms of spin-lattice relaxation are discussed.