Effects of magnetic field on triplet state of Pt–phthalocyanine single crystal

Zeeman effect of the first excited triplet state in Pt–phthalocyanine single crystal is studied in the magnetic field up to 100 kG by observing the phosphorescence emission at 4.2 K. Phosphorescence peaks are observed at the wave numbers 10 289.1 and 10 297.6 cm−1 in the zero magnetic field at 1.7 K (zero field splitting). The zero field splitting coefficients of the triplet state are estimated from the Zeeman study to be D=−7.8±0.2 cm−1 and ‖E‖=0.7±0.2 cm−1. The decay time of the emission peak of 10 289.1 cm−1 decreases with increasing magnetic field from 7 μsec at 0 G to 3 μsec at 100 kG. Z component of spin level has the largest decay rate of 3.3×105 sec−1 at zero magnetic field. Dependence of the phosphorescence intensity and the energy shift of their peaks on the direction of the magnetic field referred to the crystal axis are also measured and compared with the theoretical calculations.