Multiple bifurcations with signal enhancement in nonlinear mid-infrared thermal lens spectroscopy.
Multiple bifurcations with signal enhancement in nonlinear mid-infrared thermal lens spectroscopy.
复制标题
非线性中红外热透镜光谱中具有信号增强的多重分叉。
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
M. Sander
中科院分区：
文献类型：
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作者：
A. Totachawattana;M. Hong;S. Erramilli;M. Sander
在6 μm厚的4-辛基-4′-氰联苯（8CB）液晶层的光热光谱中，我们发现了一个新的非线性中红外振动谱区。为了增加泵浦功率值，研究了8CB样品在晶相和微晶a相的光热光谱的非线性演化，并利用泵浦探针热透镜光谱对其非平衡转变进行了表征。非线性光热现象可以用局部非平衡跃迁的成核来解释，这种非平衡跃迁导致气泡的形成，从而改变了热透镜的行为。对多重分岔的分析揭示了这些非平衡动力学的通用临界指数，可以与平均场理论联系起来。我们首次报道了在非线性状态下光热信号振幅和相位行为的同时测量。由于观察到的信号增强和光谱变窄，非线性光热行为显示出提高中红外灵敏度和信号对比度的希望，对中红外样品表征具有吸引力。
We report a novel nonlinear mid-infrared vibrational spectroscopy regime where multiple bifurcations and signal enhancement are observed in the photothermal spectrum of a 6 μm-thick layer of 4-octyl-4'-cyanobiphenyl (8CB) liquid crystal. For increasing pump power values, the nonlinear evolution of the photothermal spectrum is studied in 8CB samples initially in the crystalline and smectic-A phase and their non-equilibrium transitions are characterized with pump-probe thermal lens spectroscopy. The nonlinear photothermal phenomena can be explained by the nucleation of localized non-equilibrium transitions that leads to the formation of bubbles, which modify the thermal lensing behavior. Analysis of the multiple bifurcations reveals a universal critical exponent for these non-equilibrium dynamics that can be linked to mean field theory. We report for the first time simultaneous measurement of the photothermal signal amplitude and phase behavior in the nonlinear regime. Due to the signal enhancement and spectral narrowing observed, nonlinear photothermal behavior shows promise for improvement in sensitivity and signal contrast in mid-infrared, attractive for sample characterization in the mid-infrared.
影响因子：
13.3
作者：
Nedosekin, Dmitry A.;Galanzha, Ekaterina I.;Zharov, Vladimir P.
通讯作者：
Zharov, Vladimir P.