Photo-physical properties of anisole: temperature, pressure, and bath gas composition dependence of fluorescence spectra and lifetimes
Photo-physical properties of anisole: temperature, pressure, and bath gas composition dependence of fluorescence spectra and lifetimes
复制标题
苯甲醚的光物理性质：荧光光谱和寿命的温度、压力和浴气体成分依赖性
DOI：
10.1007/s00340-013-5420-7
复制
发表时间：
2013
期刊：
影响因子：
--
通讯作者：
C. Schulz
中科院分区：
文献类型：
--
作者：
S. Faust;T. Dreier;C. Schulz
苯甲醚是一种很有希望用作气相成像诊断荧光示踪剂的候选者。与常用的甲苯相比，其高荧光量子产率（FQY）和大斯托克斯位移可提高信号强度（高达100倍）。在266 nm的皮秒激光激发下，研究了气体苯甲醚的荧光光谱和有效荧光寿命与温度（296-977 K）和总压在1-10 bar范围内的bath gas组成（不同数量的N2和O2）的函数关系，为内燃机缸内测量等应用提供光谱数据和FQY。苯甲醚的荧光光谱范围约为270 ~ 360 nm，在296 K时峰值接近290 nm。光谱随温度（0.03 nm/K）和O2分压（从N2到空气的5 nm）的升高而发生红移。在所研究的温度范围内，在总压为1 bar的纯N2中，有效荧光寿命随温度的升高而下降，从13.3±0.5 ns降至0.05±0.01 ns。增加N2的总压会导致400 K以上温度下的寿命小幅下降（例如，在525 K下，从1 bar时的4.2±0.2 ns降低到10 bar时的2.7±0.2 ns）。在恒温和有氧气存在的情况下，寿命显著降低（例如，在296 K时，N2中的寿命从13.3±0.5 ns降至空气中的0.40±0.02 ns），随着温度的升高，这一趋势逐渐减弱（例如，在675 K时，N2中的寿命从1.02±0.08 ns降至空气中的0.25±0.05 ns）。提出了一种预测荧光寿命的现象学模型，即相对量子产率作为温度、压力和O2浓度的函数。讨论了苯甲醚的光物理性质，并与其它芳烃进行了比较。
Anisole is a promising candidate for use as fluorescent tracer for gas-phase imaging diagnostics. Its high-fluorescence quantum yield (FQY) and its large Stokes shift lead to improved signal intensity (up to 100 times stronger) compared with the often used toluene. Fluorescence spectra and effective fluorescence lifetimes of gaseous anisole were investigated after picosecond laser excitation at 266 nm as a function of temperature (296–977 K) and bath gas composition (varying amounts of N2 and O2) at total pressures in the range of 1–10 bar to provide spectroscopic data and FQY for applications, e.g., in in-cylinder measurements in internal combustion engines. Fluorescence spectra of anisole extend from roughly 270–360 nm with a peak close to 290 nm at 296 K. The spectra show a red-shift with increasing temperature (0.03 nm/K) and O2 partial pressure (5 nm from N2 to air). In the investigated temperature range and in pure N2 at 1 bar total pressure the effective fluorescence lifetime drops with increasing temperature from 13.3 ± 0.5 to 0.05 ± 0.01 ns. Increasing the total pressure of N2 leads to a small decrease of the lifetime at temperatures above 400 K (e.g., at 525 K from 4.2 ± 0.2 ns at 1 bar to 2.7 ± 0.2 ns at 10 bar). At constant temperature and in the presence of O2 the lifetimes decrease significantly (e.g., at 296 K from 13.3 ± 0.5 ns in N2 to 0.40 ± 0.02 ns in air), with this trend diminishing with increasing temperature (e.g., at 675 K from 1.02 ± 0.08 ns in N2 to 0.25 ± 0.05 ns in air). A phenomenological model that predicts fluorescence lifetimes, i.e., relative quantum yields as a function of temperature, pressure, and O2 concentration is presented. The photophysics of anisole is discussed in comparison with other aromatics.