Lanin A A, Voronin A A, Fedotov A B, Zheltikov A M
1] Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia [2] Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 1430125 Russia.
1] Physics Department, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992, Russia [2] Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region, 1430125 Russia [3] Department of Physics and Astronomy, Texas A&M University, College Station TX 77843, USA.
Sci Rep. 2014 Oct 20;4:6670. doi: 10.1038/srep06670.
When coupled to characteristic, fingerprint vibrational and rotational motions of molecules, an electromagnetic field with an appropriate frequency and waveform offers a highly sensitive, highly informative probe, enabling chemically specific studies on a broad class of systems in physics, chemistry, biology, geosciences, and medicine. The frequencies of these signature molecular modes, however, lie in a region where accurate spectroscopic measurements are extremely difficult because of the lack of efficient detectors and spectrometers. Here, we show that, with a combination of advanced ultrafast technologies and nonlinear-optical waveform characterization, time-domain techniques can be advantageously extended to the metrology of fundamental molecular motions in the mid-infrared. In our scheme, the spectral modulation of ultrashort mid-infrared pulses, induced by rovibrational motions of molecules, gives rise to interfering coherent dark waveforms in the time domain. These high-visibility interference patterns can be read out by cross-correlation frequency-resolved gating of the field in the visible generated through ultrabroadband four-wave mixing in a gas phase.
当与分子的特征性、指纹振动和转动运动相耦合时，具有适当频率和波形的电磁场提供了一种高度灵敏、信息丰富的探针，能够对物理、化学、生物学、地球科学和医学等广泛领域的一类系统进行化学特异性研究。然而，这些标志性分子模式的频率处于一个由于缺乏高效探测器和光谱仪而极难进行精确光谱测量的区域。在此，我们表明，通过先进的超快技术与非线性光学波形表征相结合，时域技术可以有利地扩展到中红外区域基本分子运动的计量学。在我们的方案中，由分子的振转运动引起的超短中红外脉冲的光谱调制，在时域中产生干涉相干暗波形。这些高可见度的干涉图样可以通过对气相中超宽带四波混频产生的可见光场进行互相关频率分辨选通来读出。
