射流冷却9-氰基-10-甲基蒽的S0和S1光谱:甲基作为分子转子( S0 and S1 spectroscopy of jet cooled 9-cyano-10-methylanthracene: The methyl group as a molecular rotor )

A Mordziński A. Le? Y Stepanenko J Rycombel L Adamowicz Experimental, Theoretical or Mathematical/ configuration interactions fluorescence ground states HF calculations molecule-photon collisions organic compounds rotational isomerism rotational states spectral line intensity vibrational states/ jet cooled 9-cyano-10-methylanthracene molecular rotor dispersed fluorescence spectra 9-methylanthracene 9-cyanoanthracene methyl group rotation torsional vibration aromatic ring frame laser induced fluorescence excitation spectrum vibrational modes relative intensities methyl internal rotational bands quantum mechanical one-dimensional rotor RHF/6-31G(d,p) approximations CIS/3-21G approximations CIS/6-31G(d,p) approximations eclipsed geometry energy barrier ground state 72 cm -1 22 cm -1/ A3350D Molecular fluorescence and phosphorescence spectra A3380 Photon interactions with molecules A3520J Molecular barrier heights (internal rotation, inversion) rotational isomerism, conformational dynamics A3370F Molecular lifetimes, absolute and relat

测定了9-甲基蒽(MA)、9-氰基蒽(CA)和9-氰基-10-甲基蒽(CMA)的射流冷却荧光激发和分散荧光光谱。MA和CMA在S0-S1原点附近的谱显示了由于甲基旋转受阻及其对芳环框架的扭转振动而产生的明显的扭转级数。此外,CMA的激光诱导荧光激发谱显示了许多振动模的分裂。用量子力学一维转子计算的跃迁解释了甲基内转动带的位置和相对强度。在RHF/6-31G(d,p）,CIS/3-21G和CIS/6-31G(d,p）近似下,用全电子量子力学方法解释了低频振动带。预测在MA的情况下，日食几何（环平面上的一个C-H）在S0和S1态都是最稳定的。CMA中甲基的构象在S1 S0激发（甲基的？12相移）时发生变化。计算结果表明,CMA在S0态的甲基转动能垒（72 cm1）比在S1态的甲基转动能垒（22 cm1）高得多,而在S0态的甲基转动能垒（72 cm1）比在S1态的甲基转动能垒（22 cm1）高得多。根据目前的量子力学计算,甲基的碳原子在S0基态时属于芳香平面,但在S1激发态时偏离了该平面。计算结果表明,CMA中甲基旋转势垒在S0基态具有6倍对称性,在S1基态具有4倍对称性。

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