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Conformational fluctuations and large fluorescence spectral diffusion in conjugated polymer single chains at low temperatures

Pullerits, Tönu LU ; Mirzov, Oleg LU and Scheblykin, Ivan LU (2005) In The Journal of Physical Chemistry Part B 109(41). p.19099-19107
Abstract
The fluorescence of single chains of the conductive polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) was studied by means of single-molecule spectroscopy at 15 K. MEH-PPV was deposited onto a surface from a toluene solution and covered with a polymer cap layer of poly(vinyl alcohol) spin-coated from an aqueous solution for protection against air. Because MEH-PPV is insoluble in water, such sample preparation guarantees that MEH-PPV chains do not mix with the cap polymer. We found that this "host matrix free" environment results in substantially stronger fluorescence spectral diffusion than that observed for conjugated polymer single chains embedded into polymer matrices. The average spectral diffusion range... (More)
The fluorescence of single chains of the conductive polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) was studied by means of single-molecule spectroscopy at 15 K. MEH-PPV was deposited onto a surface from a toluene solution and covered with a polymer cap layer of poly(vinyl alcohol) spin-coated from an aqueous solution for protection against air. Because MEH-PPV is insoluble in water, such sample preparation guarantees that MEH-PPV chains do not mix with the cap polymer. We found that this "host matrix free" environment results in substantially stronger fluorescence spectral diffusion than that observed for conjugated polymer single chains embedded into polymer matrices. The average spectral diffusion range was 500 cm(-1), and the maximum registered value reached 1100 cm(-1), which is similar to 6 times larger than the values reported before. We analyzed spectral diffusion by observation of temporal evolution of the fluorescence intensity, the position of the maximum, and the width of fluorescence spectra. We propose that the transition energy shifts are caused by the differences of the London dispersive forces in slightly different polymer chain conformations. Such conformational changes are possible even at low temperatures because the MEH-PPV single chains in our samples have more freedom for fluctuations than in the usual "in host" arrangement. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
109
issue
41
pages
19099 - 19107
publisher
The American Chemical Society
external identifiers
  • wos:000232612100011
  • scopus:27544455390
ISSN
1520-5207
DOI
10.1021/jp052189c
language
English
LU publication?
yes
id
01c91ca3-67ba-4185-8afd-4cde717abf4a (old id 151812)
date added to LUP
2007-07-03 15:58:27
date last changed
2017-08-27 05:15:43
@article{01c91ca3-67ba-4185-8afd-4cde717abf4a,
  abstract     = {The fluorescence of single chains of the conductive polymer poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) was studied by means of single-molecule spectroscopy at 15 K. MEH-PPV was deposited onto a surface from a toluene solution and covered with a polymer cap layer of poly(vinyl alcohol) spin-coated from an aqueous solution for protection against air. Because MEH-PPV is insoluble in water, such sample preparation guarantees that MEH-PPV chains do not mix with the cap polymer. We found that this "host matrix free" environment results in substantially stronger fluorescence spectral diffusion than that observed for conjugated polymer single chains embedded into polymer matrices. The average spectral diffusion range was 500 cm(-1), and the maximum registered value reached 1100 cm(-1), which is similar to 6 times larger than the values reported before. We analyzed spectral diffusion by observation of temporal evolution of the fluorescence intensity, the position of the maximum, and the width of fluorescence spectra. We propose that the transition energy shifts are caused by the differences of the London dispersive forces in slightly different polymer chain conformations. Such conformational changes are possible even at low temperatures because the MEH-PPV single chains in our samples have more freedom for fluctuations than in the usual "in host" arrangement.},
  author       = {Pullerits, Tönu and Mirzov, Oleg and Scheblykin, Ivan},
  issn         = {1520-5207},
  language     = {eng},
  number       = {41},
  pages        = {19099--19107},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Conformational fluctuations and large fluorescence spectral diffusion in conjugated polymer single chains at low temperatures},
  url          = {http://dx.doi.org/10.1021/jp052189c},
  volume       = {109},
  year         = {2005},
}