Dephasing and Decoherence in Vibrational and Electronic Line Shapes.,The Journal of Physical Chemistry B

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Dephasing and Decoherence in Vibrational and Electronic Line Shapes.
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2020-02-13 , DOI: 10.1021/acs.jpcb.9b11655
Alexei A Kananenka _{1,

2} , Steven E Strong ₁ , J L Skinner ₁

Affiliation

Absorption and emission line shapes of vibrational and electronic transitions in liquids are broadened by interactions with the "bath" (in this case, the rotational and translational degrees of freedom of all the molecules in the liquid). If these degrees of freedom are treated classically, the broadening process is often known as dephasing. If, on the other hand, the bath degrees of freedom are instead treated quantum mechanically, there is additional broadening due to what is known in the chemical-physics literature as decoherence. The question addressed in this paper is the relative importance of decoherence (bath quantum effects) and dephasing. We present general developments of this subject for absorption and emission line shapes, discover several new relationships connecting classical and quantum treatments of the bath, and also consider the Stokes shift (difference in peak frequencies in absorption and emission). We next draw some general conclusions by considering a model system whose transition-frequency time-correlation function has only one bath time scale. We then consider a realistic system of the vibrational OH stretch transition of dilute HOD in liquid D2O at room temperature. For this system, we conclude that bath quantum effects are not very important, except for the Stokes shift. More generally, we argue that this is the case for many vibrational and most electronic transitions in room-temperature liquids.

中文翻译：

振动和电子线形中的相移和去相干。

液体中振动和电子跃迁的吸收和发射线形状通过与“浴”的相互作用（在这种情况下，是液体中所有分子的旋转和平移自由度）加宽。如果对这些自由度进行经典处理，则扩展过程通常称为相移。另一方面，如果对浴自由度进行机械地量子处理，则由于化学物理学文献中称为退相干，因此会进一步扩大。本文解决的问题是退相干（浴量子效应）和移相的相对重要性。我们介绍了该主题在吸收和发射线形方面的一般发展，发现了连接镀液的经典和量子处理的几种新关系，并考虑斯托克斯位移（吸收和发射的峰值频率差异）。接下来，我们通过考虑一个模型系统得出一些一般性结论，该模型系统的转换频率时间相关函数仅具有一个浴时间标度。然后，我们考虑了在室温下液体D2O中稀HOD的振动OH拉伸振动跃迁的现实系统。对于这个系统，我们得出结论，除了斯托克斯频移外，浴量子效应不是很重要。更普遍地说，我们认为室温液体中的许多振动和大多数电子跃迁都是这种情况。然后，我们考虑了在室温下液体D2O中稀HOD的振动OH拉伸振动跃迁的现实系统。对于该系统，我们得出的结论是，除了斯托克斯频移外，浴量子效应不是很重要。更普遍地说，我们认为室温液体中的许多振动和大多数电子跃迁都是这种情况。然后，我们考虑了在室温下液体D2O中稀HOD的振动OH拉伸振动跃迁的现实系统。对于这个系统，我们得出结论，除了斯托克斯频移外，浴量子效应不是很重要。更普遍地说，我们认为室温液体中的许多振动和大多数电子跃迁都是这种情况。

更新日期：2020-02-14

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