On the Multiplicity of the Phosphorescent State of Organic Molecules

The value of the ``multiplicity'' g_u for use in the equation $k_p{\text{=2πcν}}^2{n}^2{\mathrm{(g}}_l{\mathrm{/g}}_u){\displaystyle \int }\mathrm{\epsilon d\nu ̄}$ is discussed and shown to lie in the range 1 ≤g_u≤∞. The value best suited to most organic compounds at 77°K is shown to be g_u=3. The number of emitting triplet components is shown to be readily derivable for large classes of compounds and to correlate with experiment. The effects of magnetic‐field strength on triplet component energies, on phosphorescence lifetime, on phosphorescence polarization, and on g_u are calculated and shown to produce large effects in the specific case of naphthalene‐d₈.