Third-order nonlinearities studied by femtosecond infrared methods
Third-order nonlinearities studied by femtosecond infrared methods
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飞秒红外方法研究三阶非线性
DOI：
10.1021/j100019a010
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
R. Hochstrasser
中科院分区：
文献类型：
--
作者：
T. Lian;Y. Kholodenko;B. Locke;R. Hochstrasser
介绍了一种新的飞秒红外光谱方法，并将其用于研究液体的三阶响应。该方法基于连续波探测光的选通探测，只需要一个超快脉冲和一束连续波探测光。这为在更宽的光谱范围内研究双色三阶响应提供了可能。它在这里表明，这种检测方法是敏感的探测场的幅度和相位的变化。在透明液体中，三阶极化率影响探测红外光束的几何形状、偏振和频率，所有这些都可以通过这种方法测量。介绍了利用飞秒激光泵浦和连续波红外探测器对CS2和其它液体进行研究的实例。所测得的三阶折射率进行比较，在光学区域中测量的。对于CS2，在1843 cm-1处，线性偶极极化率相关函数充分描述了核对三阶极化率的贡献;对于苯和苯衍生物，线性极化率主导核响应，但可能需要考虑偶极和超极化率的贡献。
A novelfemtosecond IR method is introduced and used to study the third-order response of liquids. This method, based on the gated detection of a CW probe beam, requires only one ultrafast pulseand a CW probe beam. This opens the possibility for the study of the two-color third-order response in a much wider spectral range. It is demonstrated here that this detection method is sensitive to the change in both the amplitude and phase of the probe field. In transparent liquids, the third order susceptibility affects the geometry, polarization, and frequency of the probe IR beam, all of which can be measured by this method. Examples of study with optical femtosecond pump and CW IR probes on CS2 and other liquids are presented. The measured third-order susceptibilities are compared to those measured in the optical region. At 1843 cm-1 for CS2 the linear dipole polarizability correlation function adequately describesthe nuclear contribution to the third order susceptibilities; for benzene and benzene derivatives, the linear polarizability dominates the nuclear response, but contributions from the dipolar and hyperpolarizability may need to be considered.