Zero-phonon lines of single molecules in polyethylene down to millikelvin temperatures

Linewidth distributions for single terrylene molecules in polyethylene have been measured in the temperature range from 30 mK to 1.83 K. The temperatu re dependence of the average linewidth is best described by a linear relati onship over the full temperature range. At 30 mK, the linewidth distributio n has a full-width at half-maximum of similar to 18.6 MHz and an average li newidth of 42.8(6) MHz. (C) 2000 Elsevier Science B.V. All rights reserved.