signature=61b566062569638cf247187a93189547,High-resolution and dispersed fluorescence examination of...

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于 2021-05-30 15:59:56 发布

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该研究详细探讨了三环胺的振动光谱，揭示了从(1)L(b)到(1)L(a)的旋转转矩方向变化，以及约400cm(-1)处的电子跃迁。通过实验数据，分析了混合激发态的特性，并利用DFT-MRCI计算确定了(1)L(a)与(1)L(b)之间的共轭交点。提出了一种两层模型来解释强的振动耦合现象。

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摘要：

The vibronic spectrum of tryptamine has been studied in a molecular beam up to an energy of 930 cm(-1) above the S(0)-S(1) electronic origin. Rotationally resolved electronic spectra reveal a rotation of the transition dipole moment direction from (1)L(b) to (1)L(a) beginning about 400 cm(-1) above the (1)L(b) origin. In this region, vibronic bands which appear as single bands at low resolution contain rotational structure from more than one vibronic transition. The number of these transitions closely tracks the total vibrational state density in the (1)L(b) electronic state as a function of internal energy. Dispersed fluorescence spectra show distinct spectroscopic signatures attributable to the (1)L(b) and (1)L(a) character of the mixed excited-state wave functions. The data set is used to extrapolate to a (1)L(a) origin about 400 cm(-1) above the (1)L(b) origin. DFT-MRCI calculations locate a conical intersection between these two states at about 900 cm(-1) above the L(a) origin, whose structure is located along a tuning coordinate which is close to a linear interpolation between the two excited-state geometries. Along the branching coordinate, there is no barrier from (1)L(a) to (1)L(b). A two-tier model for the vibronic coupling is proposed.

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