Temperature-dependent fluorescence intermittency for single molecules of violamine R in poly(vinyl alcohol)

Abstract

The fluorescence intermittency or blinking of violamine R (VR) in poly(vinyl alcohol) (PVA) is measured for temperatures spanning the glass-transition temperature (Tg) of the polymer host. Probability distributions of on- and off-time durations are acquired and analyzed for temperatures ranging from 22.5 °C (Tg − 49 °C) to 85 °C (Tg + 13 °C). At all temperatures, the probability distributions are well described by a power-law. The on-time power-law exponent (mon) undergoes a modest increase with temperature, and the off-time power-law exponent (moff) varies little with temperature. Both observations are consistent with current electron transfer models for the production and decay of the non-emissive state. Surprisingly, both mon and moff demonstrated smooth variation as the temperature transitions through Tg. This observation suggests that the local VR environment is not significantly altered over the temperature range investigated here. The onset of deviation from power-law behavior is observed at Tg + 13 °C, consistent with thermally enhanced environmental fluctuations providing for the interchange of local environments that is rapid compared to blinking.