Narrowband vibrational molecular transitions interacting with the broadband resonance of infrared plasmonic antennas lead to Fano lineshapes observed in linear (FTIR) and third-order (transient absorption and 2DIR) spectroscopic experiments. Both molecular and plasmonic components are inherently dissipative, and the effects associated with their coupling can be observed, in principle, when measuring the corresponding ultrafast quantum dynamics. We used 2DIR spectroscopy to study the waiting time evolution of quantum coherence excited in the carbonyl stretching modes of rhodium (acetylacetonato) dicarbonyl molecules, which were embedded in an 80 nm-thick polymer film spin-coated on an array of infrared half-wavelength gold antennas. Despite the pronounced Fano lineshapes obtained for the molecular transitions, and up to a four order of magnitude enhancement of the third-order signals, which taken together, indicate the coupling between the plasmonic and molecular transitions, the dynamics of the quantum coherence were identical to that obtained with 3 μm-thick film without the interaction with the plamson mode. This suggests that the coupling rate between the molecular and plasmonic excitations is significantly smaller than the relaxation rates of the molecular excitations monitored in the experiment. Here, the Fano lineshape, observed at the frequency of the molecular transition, can result from the mutual radiation damping of the molecular and plasmon modes.

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通讯：利用超快量子动力学研究红外天线阵列和分子膜之间的相互作用

窄带振动分子跃迁与红外等离子天线的宽带谐振相互作用，导致在线性（FTIR）和三阶（瞬态吸收和2DIR）光谱实验中观察到Fano线形。分子和等离激元成分本质上都是耗散的，原则上，当测量相应的超快量子动力学时，可以观察到与其耦合相关的效应。我们使用2DIR光谱研究了在铑（乙酰丙酮基）二羰基分子的羰基拉伸模式下激发的量子相干的等待时间演化，该机理嵌入了旋涂在80 nm厚的红外半波长金阵列上的80 nm厚聚合物膜中天线。尽管在分子跃迁中获得了明显的Fano线形，μm厚的胶卷，没有与plamson模式的相互作用。这表明分子和等离子体激发之间的耦合速率明显小于实验中监测到的分子激发的弛豫速率。在此，在分子跃迁频率处观察到的Fano线形可能是由于分子和等离激元模式的相互辐射衰减所致。