Gated photochemical hole burning in photoadducts of polyacenes.

Two-color, photon-gated photochemical hole burning (PHB) is observed in the absorption spectrum of a photoadduct of anthracene and tetracene (A–T) in a polymer matrix at 1.5 K. A–T undergoes PHB when irradiated with narrow band exciting light into the 0–0 band of the S1 ← S0 absorption. The efficiency of this PHB process is enhanced by simultaneous irradiation near the maximum of the Tn ← T1 absorption of A–T. Holewidths of less than 0.07 cm-1 have been observed for this photochemical cleavage of A–T. PHB was not observed for the related photoadduct dianthracene (A2) under similar irradiation conditions. [ABSTRACT FROM AUTHOR]