Pressure and composition dependences of acetone laser-induced fluorescence with excitation at 248, 266, and 308 nm
Pressure and composition dependences of acetone laser-induced fluorescence with excitation at 248, 266, and 308 nm
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DOI：
10.1007/s003400050799
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发表时间：
1999-09
期刊：
影响因子：
--
通讯作者：
M. Thurber;R. Hanson
中科院分区：
文献类型：
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作者：
M. Thurber;R. Hanson
在以前的研究中，丙酮已成功地应用作为示踪剂的平面激光诱导荧光（PLIF）的浓度和温度的测量。将丙酮PLIF能力扩展到不同压力和组成的条件的期望激发了这些量对荧光产率的影响的研究。目前的工作探讨了压力和组成的影响，在0.5至16大气压范围内的三个激发波长的诊断最感兴趣的：248，266和308纳米。在雅阁与以前的研究，荧光每丙酮分子被视为增加与压力，显然对每个波长的高压极限，在短波长观察到的最显着的效果。浴气组合物也被视为影响荧光强度，与浴气物种在振动松弛激发丙酮的有效性有关的影响。考虑激发单重态丙酮的系间交叉和振动弛豫相对速率的荧光产率模型很好地描述了测量的压力和组成依赖性。为了解释实验观察到的氧荧光猝灭效应，在模型中加入一个术语来表示氧辅助的系间交叉。数据和模型结果为诊断应用提供了有用的指导。一个关键的结论是，从最小化压力和成分依赖性的角度来看，长激发波长是优选的。
In previous studies, acetone has been successfully applied as a tracer for planar laser-induced fluorescence (PLIF) measurements of concentration and temperature. The desire to extend acetone PLIF capability to conditions of varying pressure and composition has motivated studies of the effects of these quantities on fluorescence yield. The present work explores pressure and composition effects over a 0.5 to 16 atm range for the three excitation wavelengths of greatest interest for diagnostics: 248, 266, and 308 nm. In accord with previous studies, fluorescence per acetone molecule is seen to increase with pressure, apparently towards a high-pressure limit for each wavelength, with the most significant effect observed at short wavelengths. Bath gas composition is also seen to affect fluorescence intensity, with an impact related to the effectiveness of the bath gas species at vibrationally relaxing excited acetone. A model of fluorescence yield considering the relative rates of intersystem crossing and vibrational relaxation for excited singlet acetone describes the measured pressure and composition dependences well. To explain an oxygen fluorescence quenching effect that is observed experimentally, a term is added to the model to represent oxygen-assisted intersystem crossing. The data and model results provide useful guidance for diagnostic applications. A key conclusion is that long excitation wavelengths are preferable from the standpoint of minimizing pressure and composition dependences.