Stable Single‐Molecule Lines of Terrylene in Polycrystalline para‐Dichlorobenzene at 1.5 K

Abstract

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.

Spectroscopy of Single Dibenzoterrylene Molecules in para‐Dichlorobenzene

“…We observed linewidths on the order of the lifetime limit (lifetime limits of 26.5 MHz and 29.5 MHz were reported previously for the normal and red sites in anthracene respectively): for the normal site 50 % of the molecules have a homogeneous linewidth less than 29.0 MHz, for the red site the median is about 45.0 MHz. This is in line with the observations of near‐lifetime‐limited line widths for other fluorescent polyaromatic molecules like terrylene embedded in pDCB or oDCB …”

“…There is a large energy splitting between the two sites of about 670 cm −1 . Similarly large splittings between sites were observed for terrylene in pDCB . For terrylene it was suggested that the redshift of the red site compared to the normal site is the result of an increased effective local pressure for the red site.…”

“…[22,23] There is al arge energy splitting between the two sites of about 670 cm À1 .S imilarly large splittings between sites were observed for terrylene in pDCB. [24,25] For terrylene it was suggested that the redshift of the red site compared to the normals ite is the result of an increased effective local pressure for the red site. It is likely that something similari sg oing on for DBT.T he difference in local pressure mayb ed ue to different crystal phases of pDCB.A lthough the gamma phase is the equilibrium phase at liquid helium temperatures, it is possible that some of the micro crystalso ccasionally remain in am etastable alpha-or beta-phase, depending on the thermalhistory.…”

Terrylene in a 2,3-Dichloronaphthalene Crystal. New System for Optical Single-Molecule Investigations

“…In the mentioned studies, Tr molecules, optically excited to the S 1 state, were capable to emit more than 10 5 uorescence photons before It is well known that the rate of intersystem crossing transition increases in environments possessing heavyatoms [20], by the same talk, these media are responsible for quenching of the molecular uorescence. It was * corresponding author; e-mail: kozank@ifpan.edu.pl therefore surprising that Tr in polycrystalline ortho- [21] and para-dichlorobenzene [22], both host matrices with chlorine as the heavy-atoms, create bright and highly photostable single-molecule systems. Negligible role of the external heavy-atom eect on the Tr emission may be related to much higher triplet state depopulation rate than the rate of its population [6].…”

Single Molecule as a Local Acoustic Detector for Mechanical Oscillators

“…At cryogenic temperature and in suitable rigid matrixes, the absorption spectrum of a molecule presents an extremely narrow electronic transition that occurs without any creation or annihilation of phonons, and is therefore called the zerophonon line (ZPL). Its linewidth is chiefly determined by the lifetime of the excited state and lies in the range of 10-50 MHz for many well-studied host-guest systems [13][14][15][16][17][18][19]. Because of its sharpness, the ZPL is extremely sensitive to the molecule's local environment.…”