Laser spectroscopic study of intracluster chemical reactions

1.本文综述了苯酚氢键团簇的光谱研究，重点介绍了涉及质子转移过程的团簇结构表征。本文介绍了新近发展起来的两种用于尺寸选择性团簇及其离子光谱学的实验方法。捕获离子光解离光谱表明，团簇阳离子与NH_3和H_2O等质子受体分子发生了发色团的交替;红外光谱结合电离检测表征了苯酚-水中性团簇的OH振动光谱。给出了中性团簇离子对形式的光谱证据，并讨论了团簇内酸碱反应的可能性.用红外-紫外双共振和受激拉曼-紫外双共振光谱观察了超声射流中苯酚二聚体和三聚体的OH伸缩振动。在三聚体中，所有三个OH伸缩振动显示出大的红移从裸苯酚。环状结构的证据是从IR和拉曼光谱之间的强度交替和通过测量的拉曼退偏振比。在二聚体中，发现给质子的苯酚的OH伸缩振动的IR强度比接受质子的苯酚的大4倍。

1. Spectroscopic studies of the hydrogen-bonding clusters of phenol were reviewed with an emphasis of the characterization of the cluster structures involving the proton transfer processes. Two experimental methods which were newly developed for the spectroscopy of the size selected clusters and their ions were described. Trapped ion photodissociation spectroscopy revealed that chromophore alternation occurs in the cluster cations with various proton-accepting molecules, such as NH_3 and H_2O.The infrared spectroscopy combined with the ionization detection was applied to the spectra of the OH vibrations which characterized the neutral clusters of phenol with water. The spectroscopic evidence of the ion-pair form of the neutral cluster is presented and the possibility of the intracluster acid-base reaction is discussed.2. The OH stretching vibrations of the phenol dimer and trimer prepared in supersonic jets have been observed by IR-UV double-resonance and stimulated Raman-UV double-resonance spectroscopies. In the trimer, all the three OH stretching vibrations showed large red shifts from that of bare phenol. Evidence of the cyclic structure was obtained from an intensity alternation between IR and Raman spectra and by the measurement of the Raman depolarization ratios. In the dimer, it was found that the IR intensity of the OH stretching vibration of the proton-donating phenol is 4 times larger than that of the proton-accepting phenol.