Cooling, spectroscopy and non-sticking of trans-stilbene and Nile Red

Julia Piskorski; David Patterson; Sandra Eibenberger; John M Doyle

doi:10.1002/cphc.201402502

Cooling, spectroscopy and non-sticking of trans-stilbene and Nile Red

Chemphyschem. 2014 Dec 1;15(17):3800-4. doi: 10.1002/cphc.201402502. Epub 2014 Sep 11.

Authors

Julia Piskorski¹, David Patterson, Sandra Eibenberger, John M Doyle

Affiliation

¹ Department of Physics, Harvard University, 17 Oxford St. Cambridge, MA 02143 (USA). julia@cua.harvard.edu.

PMID: 25209116
DOI: 10.1002/cphc.201402502

Abstract

We create and study trans-Stilbene and Nile Red in a cryogenic (7 K) cell with a low density helium buffer gas. No molecule-helium cluster formation is observed, indicating limited atom-molecule sticking in this system. We place an upper limit of 5 % on the population of clustered He-trans-Stilbene, consistent with a measured He-molecule collisional residence time of less than 1 μs. With its very low energy torsional modes, trans-Stilbene is less rigid than any molecule previously buffer-gas-cooled into the Kelvin regime. We also report cooling and gas phase visible spectroscopy of Nile Red, a much larger molecule. Our data suggest that buffer gas cooling will be feasible for a variety of small biological molecules.

Keywords: UV/Vis spectroscopy; buffer gas cooling; dyes/pigments; low-temperature physics; van der Waals clusters.