Wide-bandgap nonlinear crystal LiGaS2 for femtosecond mid-infrared spectroscopy with chirped-pulse upconversion.
Wide-bandgap nonlinear crystal LiGaS2 for femtosecond mid-infrared spectroscopy with chirped-pulse upconversion.
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DOI：
10.1364/ao.55.009365
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发表时间：
2016-11
期刊：
影响因子：
1.9
通讯作者：
R. Nakamura;Y. Inagaki;Hidefumi Hata;N. Hamada;N. Umemura;T. Kamimura
中科院分区：
文献类型：
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作者：
R. Nakamura;Y. Inagaki;Hidefumi Hata;N. Hamada;N. Umemura;T. Kamimura
基于啁啾脉冲上转换的飞秒时间分辨中红外光谱是一种很有前途的分子振动动力学观测方法。对非线性介质上转换的定量研究对于广泛应用仍然是必要的，特别是在频率低于2000厘米-1的情况下。我们基于含锂三元硫族化合物作为飞秒MIR光谱上转换介质的性能，对其宽带隙非线性晶体进行了评价。上转换效率是MIR脉冲频率和啁啾脉冲能量的函数。在1100 ~ 2700 cm-1的宽频率范围内，特别是在2000 cm-1以下，LiGaS2是MIR脉冲上转换的有效晶体。利用LiGaS2作为高效上转换晶体，我们开发了光谱分辨率为2.5 cm-1、时间分辨率为0.2 ps、探测窗口为120 cm-1的MIR泵浦探测光谱系统。研究了Mn2(CO)10在环己烷和牛血清白蛋白中CO伸展模式的振动弛豫动力学，具有高信噪比。
Femtosecond time-resolved mid-infrared (MIR) spectroscopy based on chirped-pulse upconversion is a promising method for observing molecular vibrational dynamics. A quantitative study on nonlinear media for upconversion is still essential for wide applications, particularly at the frequencies below 2000 cm-1. We evaluate wide-bandgap nonlinear crystals of Li-containing ternary chalcogenides based on their performance as the upconversion medium for femtosecond MIR spectroscopy. The upconversion efficiency is measured as a function of the MIR pulse frequency and the chirped pulse energy. LiGaS2 is found to be an efficient crystal for the upconversion of MIR pulses in a wide frequency range of 1100-2700 cm-1, especially below 2000 cm-1. By using LiGaS2 as an efficient upconversion crystal, we develop a MIR pump-probe spectroscopy system with a spectral resolution of 2.5 cm-1, a time resolution of 0.2 ps, and a probe window of 120 cm-1. Vibrational relaxation dynamics of CO stretching modes of Mn2(CO)10 in cyclohexane and bovine serum albumin in D2O are demonstrated with a high signal-to-noise ratio.