Hess CM, Riley EA, Reid PJ. Dielectric dependence of single-molecule photoluminescence intermittency: nile red in poly(vinylidene fluoride).
J Phys Chem B 2014;
118:8905-13. [PMID:
24995904 PMCID:
PMC4372109 DOI:
10.1021/jp505874m]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
![]()
The
dependence of single-molecule photoluminescence intermittency
(PI) or “blinking” on the local dielectric constant
(ε) is examined for nile red (NR) in thin films of poly(vinylidene
fluoride) (PVDF). In previous studies, variation of the local dielectric
constant was accomplished by studying luminophores in chemically and
structurally different hosts. In contrast, the NR/PVDF guest–host
pair allows for the investigation of PI as a function of ε while
keeping the chemical composition of both the luminophore and host
unchanged. The solvatochromic properties of NR are used to measure
the local ε, while fluctuations in NR emission intensity over
time provide a measure of the PI. PVDF is an ideal host for this study
because it provides submicron-sized dielectric domains that vary from
nonpolar (ε ≈ 2) to very polar (ε ≈ 70).
The results presented here demonstrate that the local dielectric environment
can have a pronounced effect on PI. We find that the NR emissive events
increase 5-fold with an increase in ε from 2.2 to 74. A complex
dependence on ε is also observed for NR nonemissive event durations,
initially increasing as ε increases from 2.2 to 3.4 but decreasing
in duration with further increase in ε. The variation in emissive
event durations with ε is reproduced using a photoinduced electron-transfer
model involving electron transfer from NR to PVDF. In addition, an
increase in NR photostability with an increase in ε is observed,
suggesting that the dielectric environment plays an important role
in defining the photostability of NR in PVDF.
Collapse