Rubtsova Natalia I, Kurnosov Arkady A, Burin Alexander L, Rubtsov Igor V
Department of Chemistry, Tulane University , New Orleans, Louisiana 70118, United States.
J Phys Chem B. 2014 Jul 17;118(28):8381-7. doi: 10.1021/jp502062p. Epub 2014 Apr 15.
Temperature dependence of intramolecular energy transport in perfluoroalkane oligomers with a chain length of 3-11 carbon atoms terminated by a carboxylic acid moiety on one end and a -CF2H group on another end was studied in solution experimentally and theoretically. Experiments were performed using a dual-frequency relaxation-assisted two-dimensional infrared spectroscopy method. The energy transport was initiated by exciting the C═O stretching mode of the acid and recorded by measuring a cross-peak amplitude between the C═O stretching and the C-H bending modes as a function of the waiting time between the excitation and probing. An efficient transport regime with a mean free path of 16.4 ± 2 Å is observed at 35 °C. The energy transport speed decreases at elevated temperatures, indicating a switch from the ballistic transport regime to diffusive. The modeling of the energy transport involving both ballistic and diffusive mechanisms is performed. It explains the temperature dependence of the energy transport speed and confirms a switch of the transport regime from ballistic at lower temperatures to diffusive at higher temperatures.
研究了一端由羧酸部分封端、另一端由-CF2H基团封端的链长为3至11个碳原子的全氟烷烃低聚物在溶液中分子内能量传输的温度依赖性，包括实验和理论研究。实验采用双频弛豫辅助二维红外光谱法进行。通过激发酸的C═O伸缩模式来启动能量传输，并通过测量C═O伸缩与C-H弯曲模式之间的交叉峰幅度作为激发与探测之间等待时间的函数来记录。在35°C下观察到平均自由程为16.4±2 Å的高效传输机制。能量传输速度在升高的温度下降低，表明从弹道传输机制转变为扩散传输机制。进行了涉及弹道和扩散机制的能量传输建模。它解释了能量传输速度的温度依赖性，并证实了传输机制从低温下的弹道传输转变为高温下的扩散传输。
