Yamada Yuji, Mikami Naohiko, Ebata Takayuki
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
Proc Natl Acad Sci U S A. 2008 Sep 2;105(35):12690-5. doi: 10.1073/pnas.0800354105. Epub 2008 Jul 18.
Picosecond time-resolved IR-UV pump-probe spectroscopy has been carried out to elucidate vibrational energy relaxation (VER) of the NH stretching vibrations of 2-aminopyridine monomer (2AP) and dimer [(2AP)(2)] in supersonic beams. In bare 2AP, intramolecular vibrational energy redistribution (IVR) of the NH vibrations is described by the two-bath mode model, in which the initial vibrational energy flows to the doorway states rapidly (6.5 ps) and then dissipates into the dense bath states with a time constant of approximately 20 ps. No clear difference was observed in the IVR lifetime between the symmetric and asymmetric NH(2) stretch modes. In (2AP)(2), IVR and vibrational predissociation (VP) were involved in VER. It was found that the rate constants of both IVR and VP of the hydrogen-bonded NH stretching vibration are larger than those of the free NH.
已开展皮秒时间分辨红外 - 紫外泵浦 - 探测光谱研究，以阐明超音速束中2 - 氨基吡啶单体（2AP）和二聚体[（2AP）₂]的NH伸缩振动的振动能量弛豫（VER）。在裸2AP中，NH振动的分子内振动能量重新分布（IVR）由双浴模式模型描述，其中初始振动能量迅速（6.5皮秒）流向门道态，然后以约20皮秒的时间常数耗散到密集浴态中。对称和不对称NH₂伸缩模式之间的IVR寿命未观察到明显差异。在（2AP）₂中，VER涉及IVR和振动预解离（VP）。结果发现，氢键合的NH伸缩振动的IVR和VP的速率常数均大于游离NH的速率常数。
