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 (T_g) of the polymer host. Probability distributions of on- and off-time durations are acquired and analyzed for temperatures ranging from 22.5 °C (T_g − 49 °C) to 85 °C (T_g + 13 °C). At all temperatures, the probability distributions are well described by a power-law. The on-time power-law exponent (m_on) undergoes a modest increase with temperature, and the off-time power-law exponent (m_off) 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 m_on and m_off demonstrated smooth variation as the temperature transitions through T_g. 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 T_g + 13 °C, consistent with thermally enhanced environmental fluctuations providing for the interchange of local environments that is rapid compared to blinking.