Stable single-molecule lines of terrylene in polycrystalline para-dichlorobenzene at 1.5 K.

The spectroscopic properties of single terrylene (Tr) molecules are studied in a polycrystalline matrix of para-dichlorobenzene (p-DCB) at 1.5 K. Samples grown in a glass capillary show a very strong site at 597 nm, which is redshifted by more than 700 cm(-1) from the observed transition energy for Tr in p-DCB prepared as a film on a coverslip (572 nm). Each of these two sites is characterized by measuring their single-molecule spectroscopic parameters at 1.5 K. Lifetime-limited linewidths of 45±5 MHz are found for both sites. Fluorescence detection rates reach 8×10(4) count s(-1) at saturation. The spectral trails of the majority of single molecules show no spectral jumps, indicating an absence of interacting two-level systems; however, the small distribution of linewidths may indicate weak interactions with low-frequency modes. Frequency jumps are observed for 10 % of the molecules. The complete emission spectra from two different single molecules at the center of each of the two sites is presented. Debye-Waller factors of αDW=0.33±0.05 for the normal site (572 nm) and αDW=0.30±0.05 for the red site (597 nm) are reported. This new host-guest system provides a quick and easy way to obtain lifetime-limited single-molecule lines.